Congenital Heart And Pediatric Electrophysiology

Repeat radiofrequency catheter ablation of atrial tachycardias in patients with congenital heart disease Ulrich Krause et al J Cardiovasc Electrophysiol. 2022;33:943–952   Take Home Points: Atrial tachycardias (AT) in patients with congenital heart disease (CHD) have a significant impact on morbidity and mortality. Radiofrequency catheter ablation (RFA) of the tachycardia substrates has improved outcome and is recommended by current consensus statements of the United States and European societies with satisfactory rates of acute success. Repeat ablation procedures are frequent but effective during a mean follow up of more than 4 years after the last procedure; 73% of the patients stayed in SR and 27% did not require further ablation procedures Factors associated with a greater likelihood of repeat ablations comprised: Complex atrial anatomy after Fontan palliation and atrial switch procedures Induction of multiple unstable IART during EPS Noninducibility of AT during programmed atrial stimulation after AT ablation has been described to be sufficient proof for a favorable outcome. Promising longterm success could be achieved after repeat ablation procedure. Commentary by Dr. Khyati Pandya (Augusta, GA, USA) Congenital and Pediatric Cardiac EP section editor:   The current study was aimed at evaluating the long‐term course of 144 patients with CHD requiring repeat ablation procedures (RAP) of AT between January 2003 and October 2018. Patients were classified according to the complexity of CHD: complex CHD (cCHD), moderate CHD (mCHD), and simple CHD (sCHD).   Atrial tachycardias (AT) in patients with congenital heart disease (CHD) have a significant impact on morbidity and mortality. Radiofrequency catheter ablation (RFA) of the tachycardia substrates has improved outcome and is recommended by current consensus statements of the United States and European societies and satisfying acute success rates have been reported. During mid and long‐term follow‐up, however, recurrence rates of AT ranging from 34% to 54% necessitating repeat ablation have been reported. Reports on mid and long‐term outcome after RFA of AT in patients with CHD are sparse covering only a limited number of patients and limited number of repeat procedures.   The purpose of the current study was to evaluate the mid and long‐term outcome of CHD patients requiring repeat ablation procedures of AT at University Medical Center, Georg‐August‐University Göttingen, Göttingen, Germany focusing (1) on a potential impact of the complexity of CHD on AT recurrence, (2) the role of tachycardia mechanism and ablation substrates with respect to AT recurrence, and (3) identification of potential factors associated with AT recurrence with impact on repeat ablation outcome.   RFA was performed with various 7F and 8F open‐irrigated radiofrequency ablation catheters as point‐by‐point applications (45°C, 30–50 W, 45 s/point). Since June 2012 real‐time contact force monitoring during ablation was used in all procedures (TactiCathTM, goal force 10–40g). Conduction gaps in previous ablation lines were sought and targeted.   Confirmation of acute procedural success and noninducibility after ablation were in accordance with conventional EP testing methods. Ablation endpoints were not changed over time.   In 62% of the patients, repeat RFA was performed at a single site, in 38% more than one substrate was targeted. A substrate within the CTI was targeted in 73%, a right atrial (RA)/SVA substrate other than CTI was targeted in 49%. A substrate within the left atrium (LA)/PVA was targeted in 22% procedures (22%). In 24% patients, RFA at a site different from the site targeted in the preceding procedure was performed. In 31% procedures, previous and additional substrates were targeted. In about half of those procedures, a new AT different from the initially targeted tachycardia was induced and targeted and in about the remaining half of those procedures, the same AT as targeted previously was induced and targeted again. In about 50% of the patients with dTGA post Mustard procedure, substrates other than CTI were targeted. The frequency of scars in the superior and the inferior baffles was comparable. Because of the heterogeneity of underlying CHDs details of main tachycardia mechanisms were not further analyzed for other types of CHD.     The original study population is outlined in the image above in a study published by the same group in 2017. Radiofrequency Catheter Ablation of Atrial Tachycardias in Congenital Heart Disease: Results With Special Reference to Complexity of Underlying Anatomy Ulrich Krause et al. Originally published15 Dec 2017https://doi.org/10.1161/CIRCEP.117.005451Circulation: Arrhythmia and Electrophysiology. 2017;10:e005451   Image from the original study outlining the patient demographics     FI GURE 1 The outcome of all 144 patients including all procedures. After 116 successful primary procedures (n = 116), six patients had NFU (blue box) and were excluded from further analysis; 46 patients stayed in SR (including SR, atrial rhythm (AR), and atrial paced rhythm (APR) while 64 patients had AT recurrence. Of those 64 patients, nine patients had recurrence of a single AT episode, lacking the need for re‐ablation (NR); six patients developed AF requiring pulmonary vein isolation (AF‐PVI; excluded from follow‐up [blue box]) while 49 of those 64 patients underwent a second procedure together with 15/28 patients having an unsuccessful primary procedure; 6/28 of the primary failure patients stayed in SR/AR/APR while another six patients needed NR after a single AT‐recurrence. After primary procedures 52/132 patients (39%) stayed in SR, 16/132 patients needed NR, and 64/132 patients underwent a second procedure. At final assessment 91/125 patients (patients with NFU, EPS extern, and AF‐PVI excluded) stayed in SR/AR/APR and 34/125 patients did not require re‐ablation after AT recurrence (see also Figure 3). AF‐PVI, pulmonary vein isolation for atrial fibrillation treatment; APR, atrial paced rhythm; AR, atrial rhythm; EPS, electrophysiological study; NFU, no follow‐up; NR, no re‐ablation; SR, sinus rhythm with or without antiarrhythmic drug therapy; *NR after sustained self‐limiting atrial tachycardia, **NR after sustained atrial tachycardia necessitating cardioversion), ‡already published data in Klehs et al.   TA BL E 1 Patients' and procedural characteristics with reference to the severity of CHD All reprocedures (n = 101)Simple CHD (n = 6)Moderate CHD (n = 38)Complex CHD (n = 57)p for overall comparisonp for pairwise comparisonMean age (year)37 ± 1332 ± 1244 ± 1433 ± 10p < .001p < .001aMedian body weight (kg)76 (IQR 63–88)65 (57–72)77 (67–85)77 (62–88)p = .16Median procedure duration (min)241 (IQR 203–300)145 (116–263)231 (182–280)251 (212–310)p = .008p = .03bMedian fluoroscopy time (min)16 (IQR 7.6–25)5.5 (2.9–17)10 (6.3–24)17 (12–26)p = .01p = .042bAblation site LA/PVA22 (22%)1 (17%)2 (5%)19 (33%)p = .002p = .001aAblation site CTI74 (73%)4 (67%)32 (84%)38 (66%)p = .13More than one ablation site38 (38%)013 (34%)25 (44%)p = .1New ablation site55 (54%)2 (33%)18 (47%)35 (61%)p = .22Acute success83 (82%)5 (83%)31 (82%)47 (82%)p= 1.0Recurrences after successful45/82 (55%)2/4 (50%)15/31 (48%)28/47 (59%)p= .6procedure (n = 82c) Timing of recurrences (months) 12 ± 18 6 ± 6 11 ± 12 12 ± 21 p= .32   Abbreviations: cCHD, complex congenital heart disease; CTI, cavotricuspid isthmus; LA, left atrium; mCHD, moderate congenital heart disease; PVA, pulmonary venous atrium; sCHD, simple congenital heart disease.   TABLE 2 Procedural characteristics with reference to primary procedures6 and repeat procedures All procedures (n = 245)Primary procedures (n = 144)Repeat procedures (n = 101)p ValueMore than one ablation site71 (29%)33 (23%)38 (38%)p = .01Ablation site LA/PVA31 (13%)9 (6%)22 (22%)p < .001Ablation site CTI175 (71%)101 (70%)74 (73%)p = .6Median fluoroscopy time (min)19 (IQR 11–29)22 (IQR 15–34)16 (IQR 7.6–25)p < .001Median procedure duration (min)250 (IQR 199–315)260 (IQR 197–334)241 (IQR 203–300)p = .04Acute success199 (81%)116 (81%)83 (82%)p = .7 Abbreviations: CTI, cavotricuspid isthmus; LA, left atrium; PVA, pulmonary venous atrium.   As described by the authors, ablation of more than one substrate and ablation within the LA/ PVA was significantly more frequent in repeat ablations compared with primary procedures (Table 2; 38 of 101 reprocedures [38%] vs. 33/144 procedures [23%], p=.01, and 22/101 [22%] vs. 9/144 [6%], p < .001).   FI GUR E 2 Kaplan–Meier curve of freedom from atrial tachycardia recurrence after each procedure. Log‐rank test showed no significant difference in timing of recurrence (p = .34). 12 months survival rates were after first procedure 59%, after second procedure 54%, after third procedure 55%, and after fourth procedure 88%   TABLE 3 Total number of procedures with reference to complexity of CHD Total numberAllSimpleModerateComplexofpatientsCHDCHDCHDprocedures(n = 144)(n = 18)(n = 53)(n = 73)180 (55%)13 (72%)28 (53%)39 (53%)240 (28%)4 (22%)17 (32%)19 (26%)313 (9%)1 (6%)3 (6%)9 (12%)410 (7%05 (9%)5 (7%)61 (1%)001 (1%)   Abbreviations: cCHD, complex congenital heart disease; mCHD, moderate congenital heart disease; sCHD, simple congenital heart disease.     FI GURE 4 Number of procedures for all patients with follow‐up. Number of procedures was not different in the overall comparison of the three groups, however, patients with sCHD needed significantly less procedures than patients with mCHD and cCHD (p = .04). Patients after Fontan palliation or atrial switch procedures for D‐transposition of the great arteries and patients with induction of multiple unstable IART during primary and/or repeat procedures required more procedures than the rest of the cohort. cCHD, complex congenital heart disease; mCHD, moderate congenital heart disease; sCHD, simple congenital heart disease   As described in literature, the mechanisms by which atrial arrhythmias potentially cause morbidity and mortality in CHD are multiple, including 1:1 conduction throughout atrio-ventricular node or accessory pathways, ischemia, preload reduction, embolism, systemic ventricle remodeling and consequent heart failure or ventricular arrhythmias.   The current study was a great attempt at defining factors related to recurrence of atrial arrhythmias in the population with adult congenital heart disease.   The study data has successfully demonstrated that increasing complexity of the underlying congenital heart disease correlates with an increase in the number of ablation procedures required. The higher frequency of IART in the presence of complex congenital heart disease with significant atrial stretch is somewhat intuitive.   As pointed out by the authors, the study limitations comprise of the following factors:   This study was based on retrospective data derived from a single center. A possible association of hemodynamic deterioration and AT recurrence could not reliably be assessed as hemodynamic data at the time of AT recurrence were incomplete. Patients with AF without evidence for macroreentrant tachycardia undergoing only PVI were excluded from further follow‐up. The study analyzes procedures over a time period of 15 years thereby being potentially influenced by operator skills and technical equipment. All operators, however, had the same high level of clinical experience in catheter ablation of ATs in patients with CHD and all procedures were supervised by a single senior operator.   Future prospective multicenter assessments of the results of AT ablation in CHD patients may overcome these limitations. Incorporation of cardiac MRI findings to better define areas of scarring and amalgamating the same into 3D mapping during the EP study maybe beneficial in further defining the arrhythmia substrates.   Further analysis with regards to influence of patient’s age and comorbidities on the risk of arrhythmia recurrence would be helpful as also inclusion of a broader age group. Future studies need to study the coexistence of ventricular arrhythmias and its impact on recurrence rates of atrial arrhythmias in the population of adults with congenital heart disease.   In addition, longer term follow up of these patient subgroups is required alongwith analysis of their hemodynamic data in order to better define the impact of the underlying congenital heart disease on arrhythmias.   A more thorough understanding of underlying mechanisms and substrates carries the potential to further improve outcomes as does use of novel arrhythmia mapping techniques.