Congenital Heart And Pediatric Electrophysiology

Echocardiography-Guided Risk Stratification for Long QT Syndrome. Sugrue A, van Zyl M, Enger N, Mancl K, Eidem BW, Oh JK, Bos JM, Asirvatham SJ, Ackerman MJ. J Am Coll Cardiol. 2020 Dec 15;76(24):2834-2843. doi: 10.1016/j.jacc.2020.10.024. PMID: 33303072   Take Home Points: Echocardiography can be used to assess for risk of cardiac events in patients with Long QT syndrome (LQTS) A simple and reliable echocardiographic measure, electromechanical window (EMW), was proven to be a better predictor of symptomatic LQTS compared to QTc interval. A negative EMW is associated with LQTS (-25±34 msec vs +15±20 in controls) A more negative EMW is associated with symptomatic LQTS (-52±38 vs -18±29 in asymptomatic LQTS) EMW < -40 ms was identified as the optimal threshold for LQTS risk prediction (Sensitivity: 86%; Specificity: 61%).   Commentary by Dr. Akash Patel (San Francisco, Ca, USA) Congenital and Pediatric Cardiac EP section editor: Long QT syndrome (LQTS) is associated with sudden cardiac death and identification of patients prior to these sentinel events is critical. Our current methods for risk stratification depend on a variety of factors including genotype and phenotype characteristics such specific genetic mutation, age, gender, prior cardiac events, T wave abnormalities, and QTc intervals. As phenotypic expression is variable, additional strategies are needed to help identify those at risk. This study examined the use of echocardiography to assess risk for cardiac events in LQTS with a particular focus on electromechanical dysfunction as measured by the electromechanical window (EMW).   This was a retrospective single center study at the Mayo Clinic of 997 genotype-confirmed LQTS patients who underwent an echocardiogram. A total of 346 patients were excluded due to non-digitized images for analysis (n=212) or poor quality ECG tracings (n=134). A total of 651 (65%) patients were analyzed with complete clinical, electrocardiographic and echocardiographic data. The primary outcome measure was the presence of symptomatic LQTS defined as arrhythmogenic syncope, generalized seizure, aborted cardiac arrest, appropriate ICD shock, or sudden cardiac death.   The EMW was obtained by blinded review of a continuous-wave doppler image in the apical long-axis view with concurrent ECG tracing. The EMW was calculated as the difference between the interval from QRS onset to aortic valve closure (midline) (QAoC interval) and the QT interval from the ECG, for the same beat (EMW= QAoC interval – QT interval). See figure below. Interobserver and intraobserver reliability of physicians and sonographers was also assessed on a subset of patients.     The cohort had a mean age of 26±17 years of whom 60% were female. The group included a representative distribution of Long QT Syndromes- LQTS1 (51%), LQT2 (33%), LQT3 (11%), and multiple mutations (5%). The mean QTc was 469±41 msec. There was symptomatic LQTS seen in 24% of this cohort. This was comprised of predominately syncope/seizure (74%) followed by other (15%) and cardiac arrest (11%). See figure below.     The EMW was predominately positive in normal controls (15±20 msec) and significantly negative in nearly all patients with LQTS (-25±34 msec) (p<0.0001). In addition, patients with symptomatic LQTS demonstrated a significantly more negative EMW compared to asymptomatic patients (-52±38msec vs -18 ±29 msec, p<0.0001). See figures below.       Of note, there was no significant differences in EMW between LQTS1, LQTS2, and LQTS3. However, multiple mutations were noted to have a significantly more negative EMW (-58±49 msec) compared to single mutation LQTS genotypes 1, 2, and 3 (p=0.0001). See figure below. This finding may be due to multiple mutation patients having longer QT and QTc intervals compared to the single mutation LQTS patients, though not reported in the study.     Overall, there was weak to moderate correlation between EMW and QTc interval (r=   -0.36 and r2 =0.13, p < 0.0001). Of note, there was no subgroup analyses of the QAoC interval, QT interval, and QTc interval based on LQTS genotype groups to determine which factor, if any effected the correlation between EMW and QTc. See figure below.     There was a significant portion of symptomatic LQTS patients in this cohort (24%). Based on multivariate analysis only age, EMW per 10msec, QTc per 10 msec, female gender, and LQTS3 were associated with symptoms. Interestingly, EMW per 10 msec was more significantly associated with symptoms (OR 1.37, p<0.0001) compared to the QTc interval per 10 msec (OR 1.07, p<0.006). Also, EMW per change in SD was associated with a 3-fold increase in symptoms (OR per SD, 3.00, CI: 2.34 – 3.91, p<0.0001). Of note, there was no interaction between Bazett QTc and EMW (p= 0.50). See figure below.     ROC analysis also revealed that EMW was superior to Bazett QTc in identifying symptomatic LQTS patients (AUC for EMW= 0.78 (95% CI: 0.74 to 0.81) vs. AUC of Bazett QTc = 0.70 (95% CI: 0.67 to 0.74); p=0.01). The ROC analysis did not reveal a difference between LTQ1 (AUC=0.79, 95% CI: 0.74 to 0.83) and LQT2 (AUC=0.83, 95% CI: 0.77 to 0.88 ) but was reduced with LQT3 (AUC=0.54) and multiple mutations (AUC=0.54). See figures below.       The optimal EMW cut off to determine symptomatic LQTS was considered < -40 msec which resulted in a sensitivity of 86% and specificity of 61%.   Finally, the interobserver and intraobserver variability was considered excellent after appropriate training. The interobserver reliability between reviewers for EMW (average measures ICC: 0.93; 95% CI: 0.89 to 0.96) was excellent. Intraobserver reliability for QT (average measures ICC: 0.98; 95% CI: 0.97 to 0.99), QAoC (average measures ICC: 0.97; 95% CI: 0.96 to 0.98) and EMW (average, measures ICC: 0.95; 95% CI: 0.86 to 0.99) was excellent. Based on this, EMW reporting has been consider standard clinical practice at this center since December 2019.   Overall, this study demonstrates a novel echocardiographic measure (EMW) for risk stratification in patients with LQTS. The EMW was previously identified as a risk factor in LQTS by Ter Bekke et al in 2014 across 3 centers in a smaller cohort with similar findings. This study validated these findings in larger cohort and demonstrated the feasibility to incorporate this measure into clinical practice.   The authors discuss that EMW represents the time between the end of electrical and mechanical systole. In healthy adults, this should be positive as electrical systole ends the before closure of the aortic valve. In patients with LQTS, there is a mismatch due to prolongation of electrical systole resulting in a negative EMW. The mechanism for why there is increased arrhythmias in this setting is unknown but thought to be due to abnormalities in cellular calcium handling, heterogenous mechanical /electrical ventricular dispersion, impaired relaxation, and/or modulations of cardiac mechanoreceptors. Interestingly a negative EMW in animal models of LQTS has been associated with increased lability for torsade de pointes.   The impact for treatment on the EMW was not evaluated in this study. Presumptively, some if not all of these patients were on beta-blocker at the time of their imaging and thus the impact of therapy on EMW and outcomes is unclear. However, the authors conducted a pilot study on patients who underwent left cardiac sympathetic denervation that is used to reduce events in high risk patients. They showed a reduction in EMW by 35±57 msec.   Most importantly, this study demonstrated that an echocardiographic marker of electromechanical dysfunction (EMW) was a better predictor of events in LQTS overall and in particular in LQTS1 and LQTS2 than the QTc interval. In addition, this study demonstrated that this measure could be obtained reliably and accurately with appropriate training of staff.   This study does have some limitations that may impact its generalizability. First, all clinical analysis and evaluation was done at single center by a single provider with expertise in LQTS. Second, the assessment of the QT interval on echocardiogram can be challenging as demonstrated by a removal of 13% of the cohort and the learning curve needed by sonographers/physicians to obtain accurate measures. This was due to the inability to precisely determine the end of the T-wave due to small T-wave amplitude, biphasic T-wave, or noise. Third, the lead positioning and beat-to beat HR variation impact on the QTc interval was not addressed. Finally, the authors highlight that additional markers or alternative techniques (i.e. strain, tissue doppler, etc.) for electromechanical dysfunction may prove to be superior.   Risk stratification in LQTS is critically important to minimize the risk of morbidity and mortality. This has been mainly driven by genotype, gender, age, QTc interval, and prior clinical events. This study identifies a new measure that can be incorporated in the risk assessment of patients with LQTS to better inform clinical decisions. Validation of this data in a prospective trial and/or multicenter study will aid in the generalizability of these findings.   

Risk Factors for Early Recurrence Following Ablation for Accessory Pathways: The Role of Consolidation Lesions. Dionne A, Gauvreau K, O'Leary E, Mah DY, Abrams DJ, Alexander ME, DeWitt ES, Bezzerides VJ, Triedman JK, Walsh EP.Circ Arrhythm Electrophysiol. 2020 Nov;13(11):e008848. doi: 10.1161/CIRCEP.120.008848. Epub 2020 Oct 5.PMID: 33017181   Take Home Points: Despite high acute success rates for catheter ablation of accessory pathways in pediatric patients, recurrence risk remains significant. Both patient-specific and ablation-specific factors contribute to risk of recurrence. Duration of consolidation time after successful pathway elimination appears to have some association with risk of recurrence.   Comment from Dr. Philip Chang (Gainesville, FL), section editor of Congenital Electrophysiology Journal Watch: This study by Dionne et al retrospectively reviewed their single-center experience of the ablation of accessory pathways (AP) in pediatric patients with the specific aim of identifying risk factors for pathway recurrence after acutely successful ablation. All pediatric patients who underwent AP catheter ablation between 2013-2018 were included, which yielded a primary study cohort of 525 patients and 558 procedures. Patient- and procedure-related variables were collected and analyzed together with post-ablation outcomes (primarily early- to mid-term recurrence). The primary cohort included patients with congenital heart disease and pediatric patients ranging from infancy to late-adolescence. Standard procedural setup and performance, likely similar among most centers, was described.   Among the 558 procedures performed, acute success was achieved in 97% with a recurrence rate of 8% over a median follow-up period of 0.4 years. 10% of cases were in patients with congenital heart disease (Ebstein’s anomaly most common). The median time to recurrence was 0.5 months (IQR 0-2.4 months).     The authors noted no difference in acute success between AP locations or presence of multiple AP’s. Right sided and posteroseptal AP’s had higher recurrence compared to left sided AP’s. Having multiple AP’s was associated with higher risk of recurrence. Cryoablation using any tip size was associated with higher risk of recurrence. Recurrence of AP conduction during the procedure before eventual successful elimination as well as time to AP elimination during ablation were not associated with recurrence risk. As would be expected, lack of electroanatomic mapping and placement of empiric ablations were associated with higher recurrence risk. Presence of CHD was also associated with higher recurrence.   The authors found that consolidation time after successful AP elimination was associated with recurrence with a time cutoff of 90 seconds. This was clearly distinguished from total ablation delivery time and referred specifically to the amount of additional ablation delivered after a previously successful AP ablation lesion. There was variability in the pattern of consolidation (on successful site, around successful site, or both) and frequency (between procedural eras 2013-2015 vs. 2016-2018). Consolidation was less frequently performed for posteroseptal and septal pathways. For right and left sided AP’s, consolidation time <90 seconds was associated with higher recurrence. This was not seen in posteroseptal/septal AP ablations though. Consolidation time >90 seconds was less likely for each AP in patients with multiple AP’s.     Multi-variate analysis showed multiple AP’s and consolidation time <90 seconds to remain significantly associated with risk of recurrence.   This study highlights some of the advances in pediatric AP ablation and sheds insight on where deficiencies still remain. Patient-specific variables including the presence of congenital heart disease, multiple AP’s, and non-left sided AP’s are more commonly seen in patients with AP recurrence after initial acute ablation success. Procedural variables such as non-EAM, empiric ablation delivery, and cryoablation approaches are also associated with higher recurrence risk.   The application of consolidation lesions is an interesting variable that appears to have some influence on recurrence risk. The findings from this study challenge some traditional dogmas of what is considered an adequate successful ablation, risks of collateral damage from aggressive consolidative ablations, and concerns over delaying acute/early recurrence with application of consolidation lesions at suboptimal targets. In this study, consolidation time >90 seconds seemed to be associated with lower recurrence risk. It is possible that longer consolidation time makes up for the possibility of the initial successful lesion being slightly suboptimal in location/contact/tip orientation or addresses more complex AP substrates such as branches or slanted orientations.   There are some limitations with this study, some of which were highlighted by the authors. Intra-operator variability was not controlled for and could certainly have affected outcomes. The authors noted that longer follow-up data was lacking for a sizeable portion of the cohort, which could underestimate true recurrence rates. The type of consolidation delivery was also not uniformly or systematically delivered, though time appeared to be a primary factor in predicting recurrence. Most cases in the study utilized non-irrigated ablation and EAM technique (approach to mapping and EAM system used) was not specifically assessed, which leaves out procedural variables such as high density EAM mapping, irrigated vs. non-irrigated ablation, and contact force assessment – all of which could have impact on ablation outcomes and recurrence as well. Conceptually, we would expect these tools when properly applied to facilitate acute success and reduced recurrence. Overall, the study provides great data to consider how to adjust our techniques in certain patient subgroups and AP types to potentially achieve greater long-term success.    

Etiology of Atrial Fibrillation in Patients With Complex Congenital Heart Disease – For A Better Treatment Strategy Miyazaki A, Negishi J, Hayama Y, Tsuda E, Yamada O, Ichikawa H, Uemura H, Ohuchi H.J .Journal of Cardiology. July 2020; https://doi.org/10.1016/j.jjcc.2020.06.007   Take Home Points: Atrial fibrillation (AF) in complex CHD occurs in younger patients and is more frequently associated with hemodynamic perturbations compared to its occurrence in the non-CHD population. In more complex forms of CHD with normal biatrial arrangement and AF, RA overload (predominantly volume overload) is frequently found.   Treatment including overload reduction and direct treatment of right-sided atrial arrhythmias may reduce AF burden and recurrence.     Comment from Dr. Philip Chang (Gainesville, FL), section editor of Congenital Electrophysiology Journal Watch: This study by Miyazaki et al retrospectively reviewed their single-center experience in managing patients with more complex forms of CHD and atrial fibrillation (AF) with the goal of identifying CHD-specific risk factors for the development of AF and thereby offering potential targets for treatment. The study included patients with “complex” CHD and AF treated at their center between January 1985 and November 2015. A total of 42 patients were included, all meeting criteria of age (>15 years) and normal biatrial (atrial situs solitus) forms of what appeared to be at least moderately complex CHD. The type of AF in patients was designated as paroxysmal (terminating within 7 days), persistent (sustained beyond 7 days or cardioverted within 7 days), long-standing (lasting >1 year), permanent (joint patient/physician decision to stop rhythm control efforts), and chronic (long-standing and permanent AF combined). Atrial overload was subdivided into volume and pressure overload based on echo-derived atrial dimension cutoffs and atrial pressures obtained at the time of cardiac catheterization. A number of demographic variables, CHD-related and CHD- surgery-related variables, arrhythmia history data, and various lab markers were collected when available for each included patient and used for analysis.   Among the 42 patients included, patients with tetralogy of Fallot comprised nearly 25% and 7/42 patients had persistent LSVC’s (including 4/10 tetralogy patients). Paroxysmal AF was noted in 10%, persistent in 69%, and chronic in 21%. Right atrial overload, primarily volume overload, was present in a majority of patients. (see copied figure C1-4: C1 – RA area index, C2 – RA pressure, C3 – LA area index, C4 – LA pressure).     Between patients with paroxysmal/persistent vs. chronic AF, those with chronic AF had significantly larger radiographic cardiothoracic ratios and significantly higher incidence of RA volume overload. Among all patients, 69% had other forms of SVT before and after onset of AF, with 26/29 patients having IART. Number of surgeries, presence of concomitant bradyarrhythmias or pacemakers, and presence of other atrial tachycardias did not differ significantly between these sub-groups. Over an average 9.7-year follow-up period, outcomes were highly varied, with patients in all subgroups of AF experiencing quiescence of AF, progression in AF severity/chronicity, heart failure, or death. Overall, the authors reported that 33% (14 patients) of the cohort had no AF after >1 year or following the last surgical intervention (presumably including any surgeries performed during the study period), 45% (19 patients) had chronic AF, and 36% (15 patients) died. Of the 15 patients that died, 10 had chronic AF. (*Note the patient totals here did not match the original cohort number of 42 patients)   There was little discussion of the treatments employed for AF management except that surgery, catheter ablation, pacing, and antiarrhythmic medications were employed in some. The authors only presented the treatments employed among 14 patients that had no AF after >1 year or following the last surgical intervention. Right atrial ablation and/or surgical RA volume reduction was employed in 8 of these patients.   There are substantial limitations to and problems with this study. Unfortunately, the authors appear to have simply presented all of their data collection and tried to mine some differences that met some statistical differences. Data is presented incompletely and with some errors as well. While the authors wanted to put forth the notion of a dominant contribution of atrial overload (primary RA overload), this unfortunately is terribly biased given the inclusion/exclusion criteria, small cohort size, and lack of uniformity in available data (only 25 patients had both echo and cath data). Furthermore, very little was provided to demonstrate clear association between atrial overload and the development of AF, and then clear reduction of AF burden with treatment or elimination of volume overload.   Some important findings presented in this study include the young age of CHD patients with AF, including a 24.1-year mean age in the chronic AF subgroup of the cohort. The presence of an LSVC is interesting, but was not clearly shown in this study to confer a higher risk of AF in more complex forms of CHD. It is unclear whether CS dilation by itself confers a higher AF risk. AF substrate has certainly been found and targeted in remnants of an LSVC, such as the vein of Marshall. The high incidence of progression in AF severity/chronicity over the follow-up period is also sobering. Finally, the fairly high mortality rate and high incidence of chronic AF among those who died suggests a predictive value of AF severity and chronicity on long-term survival and highlights the likely presence of AF-associated sequelae that can adversely affect survival.   The study, despite its shortcomings, puts forth what many would consider to be the CHD-specific and unique risk factors for AF development compared to the non-CHD population. Poor hemodynamics are recognized to result in chamber dilation and remodeling that predisposes to arrhythmias. Organized atrial arrhythmias can also frequently degenerate into AF. As such, we would generally expect overall improvements in AF burden with addressing hemodynamic derangements and atrial substrate modification either with surgery (chamber reduction or surgical ablation) or transcatheter ablation. Content from this study is generally consistent with what has been found and demonstrated in other studies evaluating the contribution of right heart hemodynamics, organized tachyarrhythmias, and AF ablation targets and outcomes in CHD patients.    

Low mortality in fetal supraventricular tachycardia: Outcomes in a 30-year single-institution experience O'Leary ET, Alexander ME, Bezzerides VJ, Drogosz M, Economy KE, Friedman KG, Pickard SS, Tworetzky W, Mah DY. J Cardiovasc Electrophysiol. 2020 Feb 26. doi: 10.1111/jce.14406. [Epub ahead of print] PMID: 32100356 Similar articles Select item 32113658   Take Home Points Sustained fetal SVT (defined as tachyarrhythmia present for greater than or equal to 50% of the diagnostic fetal echocardiogram) maybe associated with significant morbidity but a low mortality. The optimal management strategy for sustained fetal SVT remains unclear – multiple antiarrhythmic agents are required in over half the cases. Sustained fetal SVT in fetuses with a structurally normal heart can be effectively managed with transplacental drug therapy with minimal risk of intrauterine fetal demise. Accurate characterization of the arrhythmia mechanism on fetal echocardiogram is important, as a confident diagnosis of atrial flutter is unlikely to become a chronic arrhythmia that requires long term AAD therapy. The presence of moderate to severe ventricular systolic dysfunction in fetuses with SVT is likely associated with postnatal SVT.   Commentary by Dr. Khyati Pandya (Memphis, TN) Congenital and Pediatric Cardiac EP section editor: Mah et al describe a retrospective cohort study of fetuses with a structurally normal heart, diagnosed with sustained SVT between 1985 and 2018.         FIGURE 2: First line antiarrhythmic drug choice stratified by year of diagnosis   No cases of IUFD were observed in the study cohort. AVRT was the most common arrhythmia mechanism, responsible for approximately two of three of cases followed by AFL which was seen in one of four, as reported in previous studies.   Digoxin was popular as a first line antiarrhythmic agent throughout the time period of the study (fig 2). The arrhythmia management strategy resulted in overall survival of 97% and overall treatment success rate of 82%, however, it was noted that digoxin monotherapy did not provide consistently effective rhythm or rate control in the majority of cases, especially AVRT (36% conversion to sinus rhythm). This was in contrast with previously published studies where Digoxin was reported to convert AVRT to sinus rhythm in 57% and 69% of the patients. Their discrepant finding was attributed to practice variation with respect to digoxin dose, the timing of digoxin initiation, and the decision by the obstetrical team to deliver the fetus. 62% fetuses initially treated with digoxin monotherapy ultimately received a second line AAD regimen. The most common second line AAD regimen was the combination of digoxin and flecainide   As noted by the authors, the study had limitations for the following reasons: Only univariate associations were calculated due to the small sample size of the cohort which precluded their ability to adjust for potential confounding variables. PJRT and EAT made up the minority of cases, making it difficult to draw significant conclusions from the data. Data were collected via retrospective chart review spanning three decades with variable documentation in the electronic medical record for certain clinic variables, specifically drug dosing. The data represented in the study was thorough and exhaustive, highlighting the preferential use of Digoxin as a first line agent over three decades. The dosing regimen of various antiarrhythmic agents was elaborated. However, one of the potential challenges is accurate diagnosis of the SVT mechanism, that is often elusive on a fetal echocardiogram. Diagnosis and treatment of sustained SVT earlier in gestation can potentially help in averting progression to hydrops and premature delivery by decreasing the cumulative arrhythmia burden and thereby, the likelihood of ventricular dysfunction. More studies, of a prospective and multi-institutional nature are required to define the utility of newer available antiarrhythmic agents in the fetal and neonatal population, with a focus on safety and efficacy of antiarrhythmics in earlier stages of gestation for both the mother and the fetus.    

Cardiac Magnetic Resonance Imaging (MRI) in Children is Safe with Most Pacemaker Systems, Including Those with Epicardial Leads. Bireley M, Kovach JR, Morton C, Cava JR, Pan AY, Nugent M, Samyn MM. Pediatr Cardiol. 2020 Mar 12. doi: 10.1007/s00246-020-02316-z. PMID: 32166409 Similar articles   Take Home Points: MRI scanning at 1.5 T in patients with active/functional epicardial pacing leads appears does not appear to affect pacemaker or lead functionality. Hemodynamically stable native rhythm permits simplified ODO device programming during MRI scanning. In pediatric and young adult patients with transvenous and epicardial pacing systems, MRI scanning at 1.5 T appears to be safe provided a systematic approach is taken to scan planning, performance, and follow-up.     Comment from Dr. Philip Chang (Gainesville, FL), section editor of Congenital Heart and Pediatric Cardiac Electrophysiology Journal Watch: This study by Bireley et al retrospectively reviewed their single center experience with performing MRI studies in pediatric and young adult patients with permanent pacemakers over an 8-year period (2010-2018). Electronic records review was performed on a cohort of patients formulated by performing a query for all patients with “pacemakers” and “MRI” in records documentation. The institution had an existing protocol for managing pacemaker patients before, during, and after MRI scans. This involved pre-scan evaluation and clearance for the MRI following confirmation of a hemodynamically stable underlying rhythm when the pacemaker was programmed to ODO, pre-scan and post-scan device interrogations and re-programming, and then 2 serial outpatient visits (first visit after MRI and 6 months post-MRI). During the MRI scan itself, an “EP representative” and MRI cardiologist were present to ensure patient safety and stability. Demographic data, MRI-specific data, and pacemaker/lead data including implant date, manufacturer and model, and generator location were collected and analyzed.   A total of 21 patients who underwent 44 MRI studies were included in this study (median age 10.9 yo, 18/21 with CHD). The majority of patients had Medtronic devices (17/21) and only 3/21 generators were labeled as MRI-conditional. The majority of patients had active epicardial leads as well (17/21). All scans were performed with a 1.5 T MR scanner, of which 17/44 (39%) were primary cardiac scans. Over half of the scans were brain MRI’s (25/44, 57%) and the remaining 4% were musculoskeletal. There were no adverse events during or after MRI scans that could be attributed to the scans themselves or a scan-associated alteration in pacemaker/lead functionality. The authors reported no significant changes in pacemaker or lead functionality over ensuing device checks immediately after the scan, at first follow-up post-scan, and at 6-month follow-up post-scan. There was a statistically significant change in battery voltage (2.78 V pre-MRI to 2.77 V at follow-up, p 0.02). (see copied figure)     There are substantial limitations to this study. The retrospective design and electronic records search yielded a very small cohort of patients. Many device patients were likely excluded from MRI scans. Given the scanning protocol that was instituted, only patients with a stable underlying rhythm were scanned. However, the percentage of those who were scanned among all pacemaker patients (i.e. those with and without stable underlying rhythms) was not reported. Scans were only performed in the ODO programmed mode, but it would have been very useful to see data regarding scans with devices programmed for asynchronous pacing (and thereby including patients who would be considered pacemaker-dependent). Subjects with ICD’s were also excluded. The authors also did not include or discuss patients with abandoned leads, particularly abandoned epicardial leads, which is another group of patients who are frequently excluded from MRI studies. There was no discussion regarding the impact of implanted devices on the quality of scanned images, namely cardiac or abdominal structures, as a result of the presence of pacemakers and leads and associated artifact. And finally, contrary to the title of the study, this was not an exclusive cardiac MRI-based study, with <40% of the scans being primarily cardiac MRI’s.   Perhaps the greatest values of this study are: 1) the demonstration of safe performance of MRI studies in patients with active epicardial leads, and 2) the value of an organized approach to scanning patients with pacemakers. Concern over lead heating remains one of the main reasons why patients with epicardial leads are excluded from MRI’s. It was helpful to see that there were no adverse events attributable to heating in the study cohort, of which the majority were patients with epicardial leads. Finally, the study demonstrated the value, but also the potential personnel burden, of having a systematic approach to performing MRI studies in patients with pacemaker systems. With the potential for growth in numbers of scans performed, especially as the evidence for safety of scanning becomes more robust, it can be anticipated that requiring an “EP representative” and cardiologist at every scan (including those that are not primarily cardiac MRI’s) will need to assessed.    

Distribution of Conduction Disorders in Patients with Congenital Heart Disease and Right Atrial Volume Overload. Houck CA, Lanters EA, Heida A, et al. JACC Clin Electrophysiol. 2020 May;6(5):537-548. doi: 10.1016/j.jacep.2019.12.009 PMID: 32439038 No abstract available.   Take Home Points:   Patients with long-standing left-to-right shunts related to atrial septal defects (ASD) have significant regions of conduction delay and block in both atria and Bachman’s bundle Conduction delay and block are seen most frequently in the right atrium, esp. the inter-caval region followed by Bachman’s bundle Conduction block in Bachman’s bundle is associated with increasing left atrial size and a history of atrial fibrillation       Commentary by Dr. Jeremy Moore (Los Angeles) Congenital and Pediatric Cardiac EP section editor: This intra-operative study sought to determine the atrial conduction characteristics among 31 ASD patients (secundum 58%, sinus venosus 36%, PAPVR 7%) with long-standing left-right shunts. High resolution epicardial mapping using a 128-electrode array (spacing 2 mm) of right atrial myocardium, Bachman’s bundle and left atrium was performed before commencing on cardiopulmonary bypass. Overall, the authors found conduction delay in 2.9% and conduction block in 1.9% of the areas studied.   Conduction delay and block were most commonly seen in Bachman’s bundle and right atrium, and less commonly in the pulmonary vein region and left AV groove, although the location of both delay and block were highly variable from patient to patient. Although the right atrium was the location of the shortest lines of conduction delay (typically patch) it was also the location of the longest lines of conduction block. Further assessment of the RA revealed a predilection for conduction disorders in the inter-caval region of the right atrium. Conduction block in Bachman’s bundle was associated with increasing LA size and secundum versus sinus venosus ASDs. For patients with AF, the only difference in prevalence of conduction disorder was found in Bachman’s bundle.   The authors noted that even though the effect of long-standing ASD volume overload tends to be right atrial enlargement, conduction disorders are not exclusively situated in the right atrium but also in Bachman’s bundle and to a lesser extent within the left atrium. The authors hypothesize that conduction block in Bachman’s bundle results in a propensity to AF due to the facilitation of micro-reentrant circuits. On the other hand, more severe conduction disorders in the right atrium, especially in the inter-caval region, could predispose these same patients to atrial flutter. The results hypothesis-generating and of substantial relevance to congenital electrophysiology.      

Examination of pathological features of the right atrioventricular groove in hearts with Ebstein's anomaly, and correlation with arrhythmias. Marcondes L, Sanders SP, Del Nido PJ, Walsh EP. Heart Rhythm. 2020 Jan 21. pii: S1547-5271(20)30026-6. doi: 10.1016/j.hrthm.2020.01.013. [Epub ahead of print] PMID: 31978592 Similar articles Select item 31972995   Take Home Points: Cardiac anatomy in Ebstein’s anomaly (EA) is frequently characterized by a prominent muscular ridge along the inferior AV annulus. The presence of this ridge in postmortem hearts correlates with a clinical history of supraventricular tachycardia. The presence of an inferior annular ridge has important implications for the pathogenesis of accessory pathways in EA and may affect catheter ablation outcomes. Commentary by Dr. Jeremy Moore (Los Angeles) Congenital and Pediatric Cardiac EP section editor: Marcondes and colleagues report on the pathological features of the right AV groove in hearts with EA and correlate it with clinical evidence of arrhythmia. The study points to a prominent inferior annular ridge in many gross specimens with EA and correlates this anatomical finding with the clinical presence of accessory pathways. The authors were able to identify thirty-three cardiac specimens with EA from their insitutional cardiac registry for morphometric analysis. At blinded gross examination, a prominent ridge was identified along the inferior AV annulus in nearly half of the specimens. In addition, when correlated with a clinical history of definite or suspected arrhythmia, the ridge was identified in 7 of 10 patients with arrhythmia versus only 3 of 14 patients without arrhythmia (70% vs 21%, p=0.03). Due to the quality of the specimens that were up to 60 years old in some cases, the results of microscopic examination in this study were limited. Although accessory muscular connections were suspected by gross examination in 17 cases, this could not be verified by light microscopy. Therefore, a direct correlation between anatomic accessory connections and the presence of a fibromuscular inferior ridge could not be established in the present investigation. As the authors point out however, in the modern era, intact specimens have become a relatively rare commodity as operative outcomes have improved and surgical repair along the true tricuspid annulus is more commonly pursued. Despite these limitations, the current study contributes greatly to our understanding of the relevant anatomy for catheter ablation of accessory connections in EA. Not only should the usual impedements to successful catheter ablation (i.e. multiple accessory connections, atrial enlargement, displaced AV system conduction, diseased atrial and ventricular myocardium) be expected, but the presence of a prominent annular ridge should be routinely anticipated. The present report also opens the door to future investigations of practical implications of the study findings. For instance, it is possible that the presence of an annular ridge may correlate with specific electrogram characteristics, broad insertions, or multiple accessory connections as often observed in EA. Specific strategies to improve outcomes, such as utilization of intracardiac echocardiography (as the authors suggest) or alternatively, use of pre-procedural advanced imaging with electroanatomical mapping data, could be routinely considered to facilitate technical success for EA. Finally, coronary angiography could be considered standard practice when the operator encounters an annular ridge eithe pre- or intra-procedurally to avoid collateral damage. Ultimately, this study may raise as many questions as it answers, but it represents a major step forward in our understanding of the anatomical correlates of electrophysiology in EA.  

The Impact of Direct to Consumer Wearables in Pediatric Electrophysiology Telehealth Clinics: A Real-World Case Series. Roelle L, Dalal AS, Miller N, Orr WB, Van Hare G, Avari Silva JN. Cardiovasc Digit Health J. 2020 Oct 7. doi: 10.1016/j.cvdhj.2020.09.005. Online ahead of print. PMID: 33043315 Free PMC article.   Take Home Points: Direct to consumer wearables have played a pivotal adjunctive role in the remote diagnosis of arrhythmias, especially during the current pandemic. These tools will impact the implementation of telehealth, particularly in pediatric electrophysiology telehealth clinics. Two prominent D2C devices that provide real-time electrocardiogram (ECG) data include the KardiaMobile (AliveCor, Mountain View, CA) and the Apple Watch Series 5 (Apple, Cupertino, CA). Developing simple workflows to securely transmit and integrate these electrocardiographic tracings into the electronic medical record (in these cases, use of the MyChart application and the EPIC electronic medical record) have been described. There are important economic, reimbursement, workflow, and data integrity considerations that should be more thoroughly explored in future studies. Patient and physician workflow for obtaining and transmitting electrocardiogram (ECG) tracings from direct-to-consumer (D2C) wearable devices. The gray workflow, or “Patient Workflow,” clarifies the stepwise approach the patient takes to obtain the ECG tracing, review the tracing, and upload the tracing via the EPIC MyChart application. The screen shot images associated with each step demonstrate what the patient sees at each step. The orange workflow, or “Health Care Team Workflow,” delineates how the message appears in the EPIC inbox (Patient Advice Request>>Non-Urgent Medical Question), where the attachment hyperlink is shown, and how to reply to the patient. AF = atrial fibrillation; VT = ventricular tachycardia. Commentary by Khyati Pandya (Augusta, GA), section editor of Congenital Electrophysiology Journal Watch: The current study describes two pediatric cases using the D2C cardiac devices and discusses how they have positively impacted the telemedicine and patient experience. The authors describe two individual patients each of whom benefitted from a different D2C cardiac device. The first patient was a 20-year-old African-American man who was diagnosed at age 15 with paroxysmal atrial fibrillation. An extensive workup revealed a normal echocardiogram and a diagnostic electrophysiology study demonstrated no inducible arrhythmias. Over the next several yearly office visits, he reported having clinical episodes of AF approximately once a year, lasting seconds to minutes, that always spontaneously converted back to normal sinus rhythm. There had been no documentation of these episodes. The patient had a telehealth visit with his pediatric cardiac electrophysiology team, during which, he reported having episodes of “skipped beats” that lasted for only a few seconds, but no concerns for AF. ECG application was setup by the team and he was encouraged to obtain a real-time, “on-demand” ECG tracing using his Apple Watch (figure above). This tracing was then e-mailed to the team, by whom a real-time assessment of his heart rate and rhythm could be performed, confirming that he was in normal sinus rhythm with a rate of 89 beats per minute (bpm). In addition, the team worked with the patient to establish a workflow for submission and evaluation of future tracings using the electronic medical record, in this case using the EPIC MyChart functionality, whereby he could securely send tracings and questions to his health care team and the team could reply using a HIPAA-compliant mode of communication when the patient had symptoms concerning for AF. The Apple Watch Series 5 has the ability to provide continuous heart rate trends in addition to obtaining a single-lead ECG, or “on-demand” recording. The second patient was a14-year-old female patient with a past medical history of hypothyroidism who presented to the emergency department with an irregular heartbeat, after having tracked her heart rate by pulse assessment and pulse oximeter, between 80 and 140 bpm and associated intermittent chest pain with palpitations. She was diagnosed to have ventricular tachycardia (VT) arising from the right ventricular outflow tract (RVOT). An EPS and transcatheter ablation was acutely successful for radiofrequency ablation of her RVOT-VT with recurrence of her clinical VT several hours post procedure. The patient was started on oral verapamil and titrated to a therapeutic dose of 120 mg every 8 hours, with significant decreased premature ventricular contraction (PVC) burden and VT. An AliveCor KardiaMobile for assessment of her heart rate and rhythm at home during symptomatic events. Teaching was provided prior to discharge for family to understand the differences between sinus rhythm tracings and VT on the KardiaMobile, as well as workflow teaching for transmission of tracings using MyChart to allow for a secure, HIPAA-compliant transmission. After hospital discharge, the patient/parent transmitted multiple ECG tracings from the KardiaMobile demonstrating normal sinus rhythm, PVCs, and nonsustained VT (Figure 1), which has helped guide her outpatient medical management and drug titration. After consecutive tracings demonstrated nonsustained VT, the decision was made to pursue repeat EPS. Following repeat ablation of her RVOT-VT, follow-up KardiaMobile tracings demonstrated normal sinus rhythm with sinus arrhythmia with no PVCs at rates of 62 to 74 bpm. Symptomatic tracings recorded for concerns of chest pain or skipped beats confirmed sinus rhythm with no PVC recurrence. The authors rightly point out that integrating new, commercially available technologies into electrophysiology telemedicine clinics will be an important value-add to deriving the most benefit from these types of visits by improving physician-patient communication, diagnosis, and treatment of cardiac arrhythmias. Pediatric patients may be ideally suited to these visits and technologies, as they are often technologically savvy. Additionally, pediatric patients may have access to their parent’s D2C wearable device for obtaining ECG tracings. However, two important hurdles, as identified by the authors, are the accessibility of these devices to the vast majority of patients and economic barriers that may represent a financial hurdle to widespread adoption and implementation of these devices. More importantly, although the KardiaMobile is cheaper, the Apple device offers a significant number of additional functions by not just being a fitness partner, but also providing the ability to make calls and providing a plethora of useful apps that can help an individual attain a heart healthy lifestyle. The two patients described in this paper were older adolescents who are typically capable of seeking attention from health care providers on their own. Exceptional situations such as arrhythmic syncope, a younger child who is likely to panic during an arrhythmic episode or a specially abled adolescent, would not be able to use the KardiaMobile as the device does require coordination in the form of placing fingers on a sensor enabled pad in order to record and transmit the rhythm during symptoms. An Apple watch maybe more useful in these situations, as the automated detections would be stored as long as the watch is worn. Other questions that remain to be answered are the ability to detect these rhythms in individuals with conditions such as dysautonomia, Raynaud’s phenomenon, hyperhidrosis etc. that may interfere with the ability of the device to sense the pulse and therefore the heart rhythm. These individuals may benefit from the conventionally used event monitors with direct application of patches on the chest. KardiaMobile may represent a more economical option for patients that depend on insurance or FSA reimbursement to cover medical costs. Both systems require a paired smartphone for full functionality, which impacts the total cost. Patients and families with more disposable income may be more likely to invest in a product that will provide insight into their symptoms, diagnosis, and treatment regardless of insurance reimbursement. Additionally, for some patients, there may be personal stylistic preferences that may drive decision-making about cardiac wearables. Teenagers are often embarrassed to used devices that may draw attention from other students in a classroom setting and may end up ignoring their symptoms or waiting to transmit after class by which time the arrhythmia may have terminated. An Apple watch maybe better suited in these instances to retrieve the rate and rhythm recorded during symptoms. Thus the diagnostic abilities of any wearable device, is significantly dependent on patient compliance. The authors mention encouraging patients to obtain an ECG tracing on the day of and prior to their telehealth visit, and to utilize the MyChart application, embedded within electronic medical record, EPIC, to upload the data for review prior to/during their telehealth visit. However, institutions or facilities that have EMRs other than EPIC, may not be able to talk to wearable monitors, further limiting user friendliness. Comparative studies assessing diagnostic quality of the Apple Watch Series 5 ECG compared to standard 12-lead ECGs would provide important data to support its use in an electrophysiology telehealth clinic. In addition, various other wearable devices should also be compared with each other across different population subsets to understand the benefits and possibly enlarge the scope of usage.  

Outcomes of Atrial Arrhythmia Surgery in Patients With Congenital Heart Disease: A Systematic Review View Article Houck CA, de Groot NMS, Kardys I, Niehot CD, Bogers AJJC, Mouws EMJP. J Am Heart Assoc. 2020 Oct 20;9(19):e016921. doi: 10.1161/JAHA.120.016921. Epub 2020 Sep 25. PMID: 32972303 Free article. Take Home Points: Bi-atrial arrhythmia surgery appears to be the strategy of choice for congenital heart disease patients with atrial fibrillation (whether paroxysmal or non-paroxysmal). Recurrence of atrial tachyarrhythmia after bi-atrial arrhythmia surgery is in the order of 20% based on available follow up. Right atrial arrhythmia surgery alone appears sufficient for patients with a history of only macro-reentrant atrial tachycardias. To date, there are no published data to support isolated left atrial lesions for patients with congenital heart disease that are to undergo arrhythmia surgery. Commentary by Dr. Jeremy Moore (Los Angeles) Congenital and Pediatric Cardiac EP section editor:  This is a systematic review of the existing literature (1994-2019) on arrhythmia surgery among patients with congenital heart disease, as compiled by the Erasmus group in the Netherlands. Accordingly, the authors selected 28 studies after reviewing 2175 abstracts and 132 full-text articles. The authors categorized the types of arrhythmia surgery as 1) bi-atrial, 2) right-atrial only or 3) left-atrial only. The quality of the included studies was considered to generally be good and was compromised mostly by lack of information regarding follow up (usually when the patients of interest were included as part of a larger cohort). Of the studies included, the overall atrial tachyarrhythmia (ATA) recurrence after arrhythmia surgery was 13%. The majority (18, 64%) of studies provided a comprehensive description of the lesion sets used in the arrhythmia surgery. Unfortunately, the methods for performing arrhythmia surgery differed significantly among studies and even within studies. Bi-atrial arrhythmia surgery (n=19) In most studies that included bi-atrial arrhythmia surgery (16/19), patients had a history of atrial fibrillation (AF). Fourteen studies reported outcomes specifically after bi-atrial arrhythmia surgery. Overall, ATA recurred in 13% of patients (IQR 0-27%) and, when considering only the larger studies (> 8 patients), the reported ATA recurrence was higher at 20% (IQR 11-39%) during follow-up ranging from 1.0 to 7.4 years (see forest plot below). Right-sided arrhythmia surgery (n=19) For most of the modern studies, lesions were placed according to the right-sided Maze procedure as first proposed by Theodoro in 1998. The indication for right-sided arrhythmia surgery was AF (6), MRAT (1), both AF and MRAT (9), or prophylactic (3). Twelve studies specifically reported outcomes after right-sided arrhythmia surgery for patients with MRAT and/or AF. The median recurrence for AT/AF after right-sided arrhythmia surgery was 19% (IQR 7-29%). Three studies directly compared bi-atrial to right-sided only Maze procedures (studies by Stulak, Im, and Kobayashi and colleagues), the latter two including only ASD patients. Among all 3 studies, recurrence appeared to be higher for right-sided only Maze procedures that were performed for patients with pre-operative AF or longstanding ATA. Left-sided arrhythmia surgery only (n=5) These procedures were uncommonly performed and were isolated to subpopulations within larger studies. None of the publications reported outcomes separately. Specific congenital heart disease defects Among studies examining specific forms of congenital heart disease, bi-atrial surgery appeared more effective than right-atrial surgery for the reduction of ATA recurrence among patients with either ASD or Ebstein’s anomaly. On the other hand, only right atrial arrhythmia surgery was reported among patients with tetralogy of Fallot in one study and was associated with lower ATA recurrence as compared to isolated surgical repair. The data presented in this systematic review were inherently limited in light of the existing literature. As the authors rightly point out, most studies to date have been characterized by small sample size and resultant wide confidence bounds. The indication for arrhythmia surgery have been inconsistently stated, the surgical approach (and energy source) have varied within or across studies and follow up has been limited or not reported.  As a result, the strength of the evidence to guide specific types of arrhythmia surgery in various settings remains weak. That said, basic principles as outlined above can be used to guide the surgical approach among patients with congenital heart disease.

Impact of preoperative electrophysiological intervention on occurrence of peri/postoperative supraventricular tachycardia following Fontan surgery View Article Takeuchi D, Toyohara K, Kudo Y, Nishimura T, Shoda M. Heart Rhythm. 2020 Aug 8:S1547-5271(20)30756-6. doi: 10.1016/j.hrthm.2020.08.003. Online ahead of print. PMID: 32781159 Take Home Points: 34% of patients undergoing Fontan procedure with a prior episode of supraventricular tachycardia (SVT) will have SVT during or within the 1st year after surgery 70% of patients will have SVT due to AV nodal reentrant tachycardia or AV reentrant tachycardia due to an accessory pathway or twin AV nodes Catheter ablation for SVT prior to Fontan surgery has a high acute success rate (91%) with the majority requiring only a single procedure (93%) Use of a pre-operative EP study and catheter ablation resulted in a significant reduction in peri-/post-operative SVT after Fontan surgery (11% vs 43%) Pre-operative EP study and catheter ablation should be considered in Fontan patients with high risk for SVT Comment from Dr. Akash Patel (San Francisco), section editor of Congenital Electrophysiology Journal Watch.  Supraventricular tachycardia (SVT) in patients who undergo Fontan palliation can result in symptoms, compromised hemodynamics, and poor outcomes. Catheter ablation for SVT after the Fontan procedure can be challenging due to limited vascular and cardiac chamber access.  The utility of pre-operative EP studies and ablation prior to surgery has been shown effective in select congenital heart lesions. The data on this approach in Fontan patients is limited but important due to procedural challenges and clinical impact of SVT as mentioned. This study aimed to assess the 1) incidence, 2) impact of pre-operative EP study guided intervention, and 3) risk factors associated with peri-/post-operative SVT within 1 year after surgery in Fontan patients at high risk for SVT. This was a retrospective single center study of all patients who underwent Fontan procedure and had a history of supraventricular tachycardia (≥ 1 episode) prior to surgery.  All patients underwent Fontan procedure between January 1987 and April 2017.  EP evaluation and management varied during this time frame. Prior to 1989, no EP studies or catheter ablation were performed. After 1989, all patients deemed high risk for supraventricular tachycardia underwent and EP study and if arrhythmia was diagnosed underwent ablation – surgical ablation (prior to 1997 or if unsuccessful catheter ablation) or catheter ablation (after 1997).  The patients were then divided into three cohorts (EP study not attempted, EP study without catheter ablation, and EP study with catheter ablation) and followed clinically for at least 30 months. SVT was defined as atrioventricular reentrant tachycardias (AVRTs) associated with the accessory pathway or twin atrioventricular nodes (AVNs), atrioventricular nodal reentrant tachycardia (AVNRT), atrial tachycardias (ATs), and atrial flutter (AFL). Atrial fibrillation and junctional tachycardia with AV dissociation were excluded. Peri-operative was defined as during or ≤ 30 days after surgery.  Post-operative was defined as ≥31 days to <1 year  after surgery. All non-sustained SVTs were excluded. The overall study group included 109 patients who underwent Fontan procedure and had a history of supraventricular tachycardia (≥ 1 episode) prior to surgery.   There were 44 (40%) patients who did not undergo an EP study,  22 (20%) patients who had a EP study without catheter ablation, and 44 (40%) patients who had a EP study with catheter ablation. Typical EP study protocols were used with multiple diagnostic catheters in all cases and 3D electroanatomic mapping in 25%. Ablation was performed via radiofrequency in 38 (86%), irrigated radiofrequency in 7 (16%) ,  and cryoablation in 1 (2%) . Fontan procedures were performed ≤ 6 months after the last EP study and catheter ablation.  Fontan types included atriopulmonary (77%), lateral tunnel (7%), and extracardiac conduit (16%). Intraoperative arrhythmia surgery was performed in 11 patients which included AVN modification and accessory pathway ablation (10 were included in the EP study only group, and 1 in the EP study with catheter ablation group). The median age at Fontan procedure was 8.8 years with 11.4 years of follow-up. The EP study with catheter ablation group were significantly younger (3.8 years).   There was no differences in the type of Fontan, presence of heterotaxy, presence of AV discordance, or type of congenital heart disease between the groups. See table below. The incidence of peri-/post-operative SVT within 1 year after Fontan surgery was 34% (37/109) with most occurring peri-operatively (91%). All were sustained or incessant with symptoms and hemodynamic instability which required intervention. See figure below. Of note, 22% of the peri-operative SVT recurred after 1 month. There were 71 SVTs diagnosed in 65 patients.  The majority of SVT was due to AVRT due to twin AV nodes (44%) followed by AVNRT (17%), atrial tachycardia (17%), AVRT due to accessory pathway (10%), atrial flutter (10%) , and junctional tachycardia (1%).  See figure below. Twin AVNs were present or suspected in 67% of patients who underwent an EP Study. Of note, this cohort had  a high percentage with heterotaxy (50%). Catheter ablations (49) were performed in 44 patients before Fontan surgery.  41 (93%) only required 1 ablation with 3 (7%) required multiple procedures. The acute success rate was 91% after the initial procedure. The overall success rate after all catheter ablation(s) for SVT before Fontan surgery was 97% (43/44) of patients and 98% (52/53) of induced SVTs.  Catheter ablation was safe with no major complications such death, major hemorrhage, systemic thrombosis, and/or lethal arrhythmia. The incidence of all SVTs within 1 year after Fontan surgery was 50%  (22/44) in the no EP study group, 47%  (10/21) in the EP study without ablation group, and 11% (5/44) in the EP study with catheter ablation group. The majority of SVT  (89%) was due to AV reciprocating SVTs and only 11% due to “atrial muscle” SVT (i.e. atrial flutter/tachycardia). Of note, there was the lack of “atrial muscle” SVTs in the catheter ablation group.  The incidence of AV-reciprocating SVT was significantly lower  (11%) in EP study with catheter ablation group compared to the EP study only (43%) or no EP study group (43%) (p< 0.05). See figure below.   Risk factors for peri-/post-operative SVT within 1 year after Fontan surgery were analyzed and only a lack of or unsuccessful pre-operative catheter ablation was shown to be associated with increased risk (OR 4.43). See table below. Long term follow-up after Fontan surgery was done for a median of 11.4 (5.0–19.8) years. There were 8 early deaths (≤ 1 month after surgery) and 18 late deaths.  The causes of late death included sudden death (8), heart failure (7), systemic embolism (2), and hemodynamic collapse due to SVT (1). Of note, 5 of the late deaths occurred within 1 year after surgery due to sudden death (4) and SVT (1). All of these were in the no EP study group. Late arrhythmia occurrence was seen in 26 patients (27%) at a median of 13.5 (5.0–18.0) years after Fontan surgery.  The majority were atrial tachycardias (19) followed by SVT (9).  Of note, 1/3rd had history of SVT within 1 year of Fontan surgery.  In the catheter ablation group, there were 6 atrial tachyarrhythmias and 3 SVTs.  Of note, only 3 patients in the total cohort underwent repeat EP study with ablation and 2 were found be recurrence of prior AV reentrant tachycardia. Also, 10 patients underwent Fontan conversion during follow-up for various reasons which may have impacted arrhythmia substrate during follow-up. Overall, this study demonstrated a high incidence of SVT (34%) during and after Fontan surgery in those patients with a history of SVT before surgery. The incidence of SVT peri-operatively (during or <1 month after surgery) was 91%, post-operatively (1 month to 1 year after surgery) was 9%, and late (>1 year) was 27%.  Catheter ablation was shown to significantly reduce the risk of peri-/post-operative SVT within 1 year of surgery (11% vs. 43%).  Clearly, SVT is associated with increased early and late comorbidities including in rare instance sudden death in single ventricle patients as noted in this study. The utility of pre-operative EP studies with catheter ablation carried high acute success rates (91%) with no major complications in this population. This study adds support to and is consistent with the 2016  PACES/HRS expert consensus statement on the use of catheter ablation in children and patients with congenital heart disease. This guideline states that ablation can be useful to reduce peri-/post-operative risk for SVT when surgery will result in restriction of vascular or chamber access.  In particular, this is an important consideration as post-Fontan ablations may carry additional procedural risks such as need for transbaffle puncture or limitations in access reducing acute success rates. Clearly more data and larger sample sizes are needed to determine whom should be considered for pre-operative EP study prior to Fontan as only a lack of /or unsuccessful ablation was associated with increased risk for peri-/post-operative arrhythmia. In particular, this study had a high proportion of heterotaxy syndrome and atriopulmonary Fontans.  In addition, the impact of ablation on length of stay and  other post-operative outcome measures would be important to investigate. Finally, this study noted significant late arrhythmia occurrences of whom the majority did not have a prior EP study or ablation done.  This raises the potential for long-term benefit of a pre-Fontan EP study and ablation in a subset of patients. Management of SVTs in Fontan patients is critically important to reduce potential comorbidities such as stroke, heart failure, thrombosis, and in rare instances death.   A pre-Fontan EP study and ablation can be useful to reduce peri-/post-operative SVT in high risk patients and the long term impact of this strategy requires further investigation.

Implantable cardioverter-defibrillator therapy to reduce sudden cardiac death in adults with congenital heart disease: A registry study View Article Slater TA, Cupido B, Parry H, Drozd M, Blackburn ME, Hares D, Pepper CB, Birkitt L, Cullington D, Witte KK, Oliver J, English KM, Sengupta A.J Cardiovasc Electrophysiol. 2020 Jun 24. doi: 10.1111/jce.14633. Online ahead of perindopril: 32583559 Take Home Points: The decision to implant a cardioverter defibrillator (ICD) is challenging and current guidance on the subject relies heavily on registry data and consensus. The largest studies have focused specifically on tetralogy of Fallot and transposition of the great arteries, though a large metanalysis included rarer conditions. Similar proportions received appropriate defibrillation in the primary and secondary prevention groups. Patients with advisory leads accounted for 38% of all complications in the primary prevention cohort and 33% in the secondary prevention cohort raising the possibility that future cohorts, with more reliable ICD hardware, may be exposed to lesser risk from inappropriate therapies and device revisions. Commentary from Dr. Khyati Pandya (Augusta, GA), section editor of Congenital Electrophysiology Journal Watch:  The authors describe their experience with follow-up of patients with adult congenital heart disease at risk for sudden cardiac death from a large quaternary center in the UK, who underwent implantation of an ICD. The most up to date European guidelines are not dedicated to the ACHD population and a recent study implied that these, and the US guidelines, have limited ability to predict sudden death. The objective of the current study was to gather data on the consequences of ICD implantation, including appropriate and inappropriate therapy, as well as the rate of complications over a long duration of follow up. All ACHD patients with an ICD implanted between March 2002 and March 2020 were included. Standard secondary prevention indications for ICD implantation comprised: cardiac arrest due to ventricular arrhythmia or sustained ventricular tachycardia (VT) with symptoms or other evidence of hemodynamic compromise, in line with established guidelines. The remaining patients were classified as requiring an ICD for primary prevention. Thus the subset of patients qualifying as candidates for primary prevention of sudden cardiac death were not well defined. This observational study comprised of a cohort of 136 individuals with ACHD: 79 with primary prevention device indications and 57 with secondary prevention ICDs. It incorporates a longer average follow up period than previous similar studies: 8.3 and 9.6 years in the respective primary and secondary cohorts compared with a maximum of 4.6 years in the existing literature. An appropriate therapy rate of 38% of the full cohort, equally balanced in each group, balanced against a rate of inappropriate therapy of 26% (30% for primary prevention and 19% for secondary prevention) are comparable to those in previous studies, as noted by the authors. Risks and benefits of ICD insertion are carefully balanced, particularly in the relatively young group of patients with ACHD. Both inappropriate and appropriate shock therapies have been associated with increased rates of anxiety, depression and reduced social function. An inappropriate rate of shock in 16% of patients compares well with the overall proportion of 25.2% of patients receiving inappropriate cardioversion/defibrillation in the - by Vehmeijer et al. ((Anatol J Cardiol 2018; 19: 401-3) ) Sudden cardiac death (SCD) is a major cause of mortality, accounting for roughly 19%– 26% of all deaths in ACHD patients, often occurring before the age of 40 years. As SCD in ACHD patients is often due to ventricular arrhythmias, implantable cardioverter defibrillator (ICD) may seem an ideal option to prevent SCD in these patients. However, ACHD patients are also at an increased risk of complications due to ICD implantation and inappropriate ICD shocks. In addition, the financial aspect of ICD implantation is also of importance. Both - underimplantation of ICDs, causing mortality in ACHD patients because of a preventable cause of death, as well as over-implantation, are important issues. The ICD recommendations in the current guidelines on the primary prevention of SCD in ACHD patients currently only recognize 35%-41% of SCD cases and have a poor discriminative ability. It is therefore highly important to focus future research on ICD recommendations specific for ACHD patients. This will require international multicenter cooperation, funding, and great effort from physicians and researchers as the population of ACHD patients continues to increase and grow older. Achievement of these goals in the COVID era, as well as the resource depleted post COVID era is likely to pose significant challenges.

Incidence and fate of device-related left pulmonary artery stenosis and aortic coarctation in small infants undergoing transcatheter patent ductus arteriosus closure View Article Tomasulo CE, Gillespie MJ, Munson D, Demkin T, O'Byrne ML, Dori Y, Smith CL, Rome JJ, Glatz AC. Catheter Cardiovasc Interv. 2020 Apr 27. doi: 10.1002/ccd.28942. [Epub ahead of print] PMID: 32339400 Take Home Points: Transcatheter PDA closure is the preferred treatment option for nearly all patients with PDAs, even those near 1 kg, at most centers LPA stenosis and aortic coarctation are known risk factors in infants undergoing PDA closure This study supports that the majority of LPA and aortic obstruction tend to improve over time Commentary from Dr. Ryan Romans (Kansas City, MO), section editor of Congenital Heart Disease Interventions Journal Watch:   Transcatheter PDA closure (TC-PDA) is at least as safe and as efficacious as surgical ligation and offers a lower morbidity option. It has long been the standard for larger infants, children, and adults. The number of available devices that are able to be delivered through small sheaths has led to improved outcomes in TC-PDA and allowed for closure in smaller infants who were previously routinely referred for surgical PDA ligation. Left pulmonary artery (LPA) stenosis and aortic coarctation are known concerns in this patient population and are well described. However, longer term outcomes of these complications are not known. Tomasulo et al. report on a retrospective analysis of all infants ≤ 4 kg who underwent TC-PDA from 2007-2018. A total of 44 infants met inclusion criteria and had successful TC-PDA. The median weight was 2.8 kg (range 1.2-4 kg), with a trend towards lower weights later in the study time frame (6/10 from 2018 weighed <2 kg). The majority of patients (30/44) underwent PDA closure with an Amplatzer Vascular Plug II (AVP-II), 10 with an Amplatzer Duct Occluder II-Additional sizes (ADOII-AS, now known as the Piccolo device), 3 with an Amplatzer Duct Occluder I (ADO1), and 1 with an Amplatzer Vascular Plug I filled with 3 Cook embolization coils. The devices were placed via an antegrade approach from the femoral vein in all patients. Arterial access was obtained in 59% of patients, though in only 3/17 patients since 2017 (and none who had an ADOII-AS device placed). Type F (61%) and Type C (23%) PDAs made up the large majority of cases. Of the 44 patients, 39 had post procedure echocardiograms performed, all of which showed complete closure of the PDA. Angiography showed mild or less residual shunt in the other 5. Median follow up was 0.7 years (range 2 days-7 years) with 38 patients having assessment for LPA stenosis and aortic coarctation. Of these 38 patients, 21 patients (55%) had obstruction in at least 1 vessel. A total of 17 patients had mild flow acceleration (defined as an echocardiographic flow velocity of 1.5-2 m/sec) or stenosis (flow velocity >2 m/sec) in the LPA (though 3 of these already had flow acceleration/stenosis on their pre procedure echocardiogram). The majority of these improved as shown below. Those who developed LPA obstruction were younger, had larger PDAs, and were less likely to have an AVP II device placed. A total of 4 patients developed flow acceleration in the aorta (flow velocity 1.5-2 m/sec) and 3 developed mild aortic coarctation (flow velocity >2 m/sec). Of these, 4/7 had improved at the time of last follow up as detailed below. Lower birth weight was the only statistically significant factor associated with aortic obstruction, though there was a trend towards later gestational age and shorter PDAs. This study confirms that LPA and aortic obstruction are frequently seen in TC-PDA in small infants. However, the amount of obstruction seen is typically quite mild and likely clinically irrelevant. Additionally, most of the obstruction improves over time and none of the patients in this cohort required additional intervention (though other studies on TC-PDA closure in small infants have shown a small number requiring intervention). While this study adds reassuring information to the literature, the types of devices being used in this population is changing. The Piccolo device now has FDA approval for TC-PDA in this patient population and is now most interventionalists go to device. Additionally, the MVP microvascular plug (Medtronic) has frequently been used for TC-PDA closure in small infants and is not reported on in this study. Future studies are warranted to evaluate these known problems with the devices that are more frequently used today.

Here today, gone tomorrow: Outcomes of residual leak following secundum atrial septal defect closure with the GORE CARDIOFORM Septal Occluder View Article Gordon BM, Abudayyeh I, Goble J, Collado NA, Paolillo J. Catheter Cardiovasc Interv. 2020 Apr 1;95(5):932-936. doi: 10.1002/ccd.28666. Epub 2019 Dec 26. PMID: 31876383 Take Home Points: Residual leaks following device closure of secundum atrial septal defects, particularly when using the GORE CARDIOFORM Septal Occluder, are poorly understood. Patients with larger defects, smaller aortic rims, and with the presence of multiple fenestrations are more likely to have residual leaks following ASD device closure with the GSO. Residual leaks following ASD device closure with the GSO frequently disappear within the first year following implantation. Commentary from Dr. Arash  Salavitabar (Ann Arbor, MI), section editor of Congenital Heart Disease Interventions Journal Watch:  In this retrospective, multicenter study, the authors aimed to review experiences with outcomes of residual leaks following device closure of secundum atrial septal defects (ASD) with the GORE CARDIOFORM Septal Occluder (GSO) during the pivotal and continued access study. This is a well-known potential issue post-device closure of ASDs and the expectant course is not well-described, particularly with this device. One important characteristic of the GSO device is that it is not “self-centering”, and so it has the ability to shift as it conforms to the septal anatomy. This can lead to potential small leaks around the edge of the device. The authors sought to characterize the medium-term outcomes of residual leaks noted with the GSO and to report on potential risk factors associated with eventual closure rates. This study included 69 patients who had a residual leak following device implantation, out of 374 total patients who underwent ASD closure with the GSO for the pivotal and continued access U.S. trials. Sixty-five (17.5%) patients met inclusion criteria following retrospective review of their echocardiograms. When comparing those with and without residual leak, those with residual leaks had larger defects (10.33 ± 3.05 mm vs. 9.13 ± 2.89 mm, p = .006), larger stop flow balloon sizes (12.91 ± 3.02 mm vs. 11.43 ± 2.89 mm, p < .001), smaller aortic rims (4.87 ± 3.33 mm vs. 6.17 ± 3.78 mm, p = .019), the presence of multiple fenestrations (43.08% vs. 18.69%, p < .001), and increased fluoroscopic time (16.02 ± 9.65 min vs. 13.17 ± 9.03 min, p = .004). Larger devices tended to be implanted and more devices per case were utilized in the residual leak cohort as compared to those without leak. There was no significant differences between procedural time, device- to-defect ratio, or type of anesthesia among groups. Importantly, there was a significant decrease in the leak size over 1 year in those patients with residual leak, from 1.55 ± 0.75mm to 0.25 ± 0.74mm (p < 0.001), with the majority disappearing by that 1 year follow-up (Figure 1). The authors postulate that residual shunts adjacent to ASD closure devices disappear over time due to remodeling of the right atrium with subsequent normalization of right atrial size following removal of the volume load caused by the ASD. This is thought to augment the endothelialization that occurs from adjacent tissue. While this study is limited by its retrospective nature, it provides important information regarding risk factors for residual leak following ASD device closure, particularly with the GSO. It is also valuable to understand that these residual leaks frequently completely disappear over the first year following implantation, which can affect patient counseling, frequency of follow-up, and potential need for future interventions.

Impact of Cardiac Resynchronization Therapy on Heart Transplant-Free Survival in Pediatric and Congenital Heart Disease Patients. Chubb H, Rosenthal DN, Almond CS, Ceresnak SR, Motonaga KS, Arunamata AA, Long J, Trela AV, Hanisch D, McElhinney DB, Dubin AM. Circ Arrhythm Electrophysiol. 2020 Apr;13(4):e007925. doi: 10.1161/CIRCEP.119.007925. Epub 2020 Mar 22. PMID: 32202126 Similar articles Select item 32301336   Take Home Points:   Cardiac Resynchronization Therapy (CRT) has become a mainstay in adult heart failure management and a potential option in children with and without congenital heart disease. CRT is associated with improved transplant-free survival in those patients with symptomatic heart failure (AHA Stage C or D), ventricular dysfunction (systemic ventricular EF <45%), and electrical dyssynchrony (QRS duration Z-score ≥ 3 or ventricular paced ≥ 40%). Heart transplantation or death was significantly lower in the CRT group compared to controls, 19% vs 58% (hazard ratio, 0.24, p<0.001). CRT was effective in pediatric patients with congenital heart disease, cardiomyopathy, and systemic RV failure. CRT was associated with sustained improvements in ejection fraction at 5 years. Comment from Dr. Akash Patel (San Francisco), section editor of Congenital and Pediatric Electrophysiology Journal Watch.  Heart failure among pediatric patients with and without congenital heart disease continues to provide challenges due to varying efficacy of anti-congestive therapy and limitations on advanced therapies such as heart transplantation. Cardiac resynchronization therapy (CRT) for the treatment of heart failure in adults without congenital heart disease (ACHD) is well established and has shown improvements in ventricular function, functional status, and mortality. The role of CRT in pediatric patients with and without congenital heart disease remains limited due to the small numbers of patients. In particular, the pediatric cohort is impacted by the large heterogeneity of congenital heart disease lesions, morphology of the systemic failing ventricle (right vs. left), variations in circulation (univentricular vs. biventricular), variations in patient size during childhood, and limited follow-up. In addition, the primary outcomes of CRT studies in pediatrics has focused on improvements in ventricular function and not on long term survival. This study aimed to assess the impact of CRT in pediatric patients with and without congenital heart disease on transplant-free survival. This was a retrospective case-control single center study of pediatric patients  (≤ 21 years) with and without congenital heart disease from 2004-2017 who had reduced systemic ventricular function (ejection fraction < 45%),  symptomatic heart failure (AHA Stage C or D), and electrical dyssynchrony (unpaced QRS duration z-score ≥ 3 or ventricular pacing ≥ 40%).  Cases were enrolled at time of implant and defined as patients who underwent CRT implantation during this time frame with ≥ 1 lead on the systemic ventricle.  Controls were enrolled at first outpatient visit meeting inclusion criteria and were subsequently matched using propensity scoring.  Exclusion criteria included Eisenmenger syndrome, current VAD, previous heart transplant, and weight <4 kg. See Figure Below The clinical practice for determining who underwent CRT placement during this time period was made on an individual basis through a multidisciplinary approach involving the heart failure, electrophysiology, and surgical teams.  After implantation, optimization of device programming was based on routine clinical practice which changed in 2016. Pre-2016, optimization was focused primarily on echocardiographic assessment for mechanical dyssynchrony and cardiac output. Post-2016, optimization was focused primarily on electrocardiographic assessment of  electrical dyssynchrony. Baseline clinical, device, electrocardiographic, and echocardiographic data were obtained. Follow-up data was obtained at 6 (±3) months, 1 (±0.5) years, 2 (±0.5) years and 5 (±1) year when available. Outcome measures included death or heart transplantation, overall survival, time to first transplant listing, and time to first heart failure hospitalization. The study group included 86 with CRT, 133 controls,  and 63 propensity score matched (PSM) pairs. Of note, 6 cases (10%) had CRT turned off in > 1month for reason other than death or transplant. These patients were included in the CRT group for analysis. See Figure Below. The median age of the CRT-PSM cohort was 11 years with 62% male and 81% with congenital heart disease. The systemic ventricle was left in 81% with a mean systemic EF of 32%. The  mean QRS duration z-score was 8.1. The median NHYA Class was 2. Only 5% were listed for transplant at baseline. There was no significant difference with controls across a total of 21 indices used match cases and controls (only 10 shown in table below). There was no difference in type of circulation (biventricular vs univentricular) and systemic ventricle (left vs right) between the PSM-CRT and control groups. The median follow-up was 2.7 (0.8 – 6.1) years overall and 2.4 (0.6 – 5.1) years for non-transplanted survivors. The CRT approach was affected by size and anatomy with the majority of devices implanted being epicardial CRT-P. See Figure Below. Overall, heart transplantation or death was significantly lower in the CRT group compared to controls, 12 (19%) vs. 37 (58%), [HR of 0.24, (95% CI, 0.12–0.46), p <0.001]. In addition, the CRT group had a higher rate of overall survival and survival without heart failure hospitalization or transplant listing.  See Figures Below. Risk factors associated with death or transplantation after multivariate analysis included increased risk with higher NHYA/Ross Class and decreased risk with use of CRT and presence of congenital heart disease. Subgroup analysis showed CRT was effective in improving transplant-free survival in those with and without congenital heart disease, in those without and without the need for bradycardia pacing, and those with systemic right ventricles.  In this cohort, CRT in univentricular anatomy did not demonstrate significant improvement upon transplant-free survival. Longitudinal follow-up showed the median QRS duration decreased 23 msec (95% CI, −38 to −6 msec) in the PSM-CRT group and increased 1 msec  (95% CI, −4 to +8 msec) in the PSM-control group at 6 months (P<0.001).  Of note, there was a disproportionate decline in PSM controls over time, but a significant increase in absolute QRS duration from baseline over time. There was no mention of Z-score change over time. See Figure Below. Longitudinal follow-up showed a significant increase in median systemic ventricular EF  at 6 months,  11% (95% CI, +0.5% to +21%) in the PSM-CRT group compared to 0.1% (95% CI, −9.8% to +3.2%) in the PSM-control group  (P<0.001).   Of note, there was a disproportionate decline in PSM controls over time, but a significant increase in absolute and change from baseline EF over time. Device complications were noted in 5% (acute) and 31% (chronic) with lead issues as the most common complication. There was no mortality with CRT procedures. See Table below. Device therapy was noted in both groups. Appropriate shocks for VF/VT was seen in 4 patients in the CRT-D group and 2 in the control group with ICDs. Inappropriate shocks were seen in 2 patients in CRT-D group  and none in the control group with ICDs. This study demonstrates the improved transplant-free survival for pediatric patients with and without congenital heart disease who received CRT for symptomatic heart failure (AHA Stage C or D and systemic EF < 45%) with electrical dyssynchrony  (QRS duration z-score ≥ 3 or ventricular pacing ≥ 40%). The design of this study allowed for a more robust retrospective analysis of CRT therapy in pediatric patients than prior studies using propensity score matching and providing a longer term of follow-up with a median of 2.7 years Overall, there was improvement in ventricular function seen at 6 months and throughout follow-up to 5 years. However, a limitation of this study was the assessment of ventricular function with LV EF extrapolated from shortening fraction when EF by Simpson method was not available. In addition, the RV EF was estimated from fractional area change for the systemic RV. In addition, there was attrition during follow-up limiting data over time. Of further interest would be the assessment of CRT on longitudinal  function (EF)  in the univentricular heart which was not associated with survival benefit and in the systemic right ventricle which was associated with survival benefit in this cohort. Heart failure functional status also plays a key role due to its impact on management decisions and survival outcomes. A lower function status at baseline was associated with a reduced risk for death or transplantation in this study. In addition, the presence of CRT was associated with improved survival to first heart failure hospitalization or transplant listing.  Due to sample size and objectives, subgroup analysis was not performed to assess risk factors for heart failure hospitalization or transplant listing. QRS duration has been an important predictor of response to CRT in adults without congenital heart disease. All patients in this study had significant conduction disease and CRT resulted in a significant decrease in QRS duration. However, it appears that the paced QRS duration remained >120 msec in the majority potentially impacting the degree of response.  The varied response to CRT is multifactorial based on variations in bundle morphology (i.e. left vs right ventricular dyssynchrony), anatomy, lead locations, and optimization protocols. In this study, the location of multisite ventricular pacing positions was not standardized or analyzed.  In addition, the optimization prior to 2016 was based on echocardiographic assessments thus resulting in limited follow-up using electrocardiographic optimization. Despite these variations, CRT showed improvement in overall transplant-free survival. Overall, this study showed that  81% of those who had CRT were alive without heart transplantation compared to the 42% in the control group.  This association between CRT and transplant-free survival remained significant  when controlling for confounders. However, due to the heterogeneity of patients and approaches in this study,  not all groups may demonstrate similar findings in a generalizable population. This study provides additional data regarding the potential benefits of CRT in pediatric heart failure with and without congenital heart disease.  However, more data is needed with homogenous congenital populations, standardized approaches,  and longer term follow-up to determine those who will respond to CRT that can  be used to ultimately refine existing guidelines. Management of heart failure in peditric patients is important to reduce mortality, transplantations, hospitalizations, and comorbidities. As mentioned in this study, a multidisciplinary  approach is needed when determining who and how one should receive CRT therapy. In addition, medical and device optimization management will continue to require an individualized approach.