Anderson C, Rahman M, Bradley DJ, Breedlove K, Dick M, LaPage MJ, Martinez AR, McNinch NL, Moore JP, Papagiannis J, Razminia M, Shannon KM, Shauver LM, Tuzcu V, Clark JM.Cardiol Young. 2021 Mar 26:1-6. doi: 10.1017/S1047951121001086. Online ahead of print.PMID: 33766172
Take Home Points:
- There have been notable improvements over time in safety and success of catheter ablation procedures for common pediatric SVT.
- The integration of 3-dimensional electroanatomic mapping is likely a dominant contributor to measureable improvements in pediatric SVT ablation success and reduction of complications.
- 3-dimensional electroanatomic mapping temporally appears associated with and capable of significantly reducing the use of and dependency on fluoroscopy during pediatric SVT ablation procedures.
Comment from Dr. Philip Chang (Gainesville, FL), section editor of Congenital Electrophysiology Journal Watch: This study by Anderson et al retrospectively reviewed data from an international, multi-center data registry derived from 6 participating pediatric centers (Catheter Ablation with Reduction or Elimination of Fluoroscopy [CAREF]) and compared it to published data from the Prospective Assessment after Pediatric Cardiac Ablation (PAPCA) registry with regards to catheter ablation for conventional pediatric SVT. The principle aim was to assess the impact of incorporation of 3-dimensional electroanatomic mapping (EAM) systems on safety of, outcomes of, and radiation exposure during pediatric SVT ablation. Registry patients were 0-16 years in age and underwent ablation for either accessory pathway (AP)-mediated SVT or AVNRT. Those with more than trivial CHD, cardiomyopathy, or concomitant procedures performed together with ablation were excluded. CAREF registry patients were enrolled between 9/2006-9/2018. Demographic, clinical, ablation procedure, and outcomes data were collected and compared to similar metrics evaluated in the PAPCA registry. Of note, fluoroscopy dose was not universally recorded from all participating centers and was therefore not compared. Also, cryoablation use was not a part of the PAPCA registry. A total of 786 procedures/patients comprised the CAREF study group with 481 patients from the PAPCA registry serving as a matched cohort for comparison. The first referenced table provides a general comparison of patient demographic and procedural characteristics. Comparable demographic and patient characteristics were noted between the 2 study groups. Total procedure time and fluoroscopy time were significantly shorter in the CAREF group with 3-dimensional EAM integration. Additionally, slightly more than 3/4 of the CAREF group (77.3%) underwent fluoroscopy-free procedures. Among procedures where fluoroscopy was used, the duration had a wide range (0-61 minutes). Major complications occurred less frequently in the CAREF group compared to the PAPCA group (0.3% vs. 1.6%, p <0.01).
The second referenced table provides comparative data regarding procedural success broken down by substrate location and mechanism of SVT. Overall success rates were generally comparable, without statistically significant differences for acute success rates across SVT mechanisms, with the exception of significantly higher success rates in the CAREF group compared to the PAPCA group for WPW (96.4% vs. 93%, p 0.02). Success rates were also generally higher in the CAREF group compared to the PAPCA group with regards to accessory pathway locations (though slightly lower success in CAREF for left septal location). Within the CAREF group, patients who received both RF and cryo-ablative approaches had lower overall success than those using 1 or the other modality (92.5% vs. 97.8% RF and 98.7% cryo).
The study demonstrates some generally encouraging findings and trends in the ablation of common pediatric SVT. In general, procedures are shorter and safer, and likely more successful, when a more contemporary era (CAREF) is compared to an earlier-era registry (PAPCA). Fluoroscopy time was markedly reduced in the CAREF group compared to the PAPCA group, which is also a very encouraging trend and finding to report. Coupled with newer fluoroscopy systems with specific functions to automatically reduce fluoroscopy radiation delivery and therefore absorbed dosage, the amount of radiation dosage spared to patients and staff is likely even lower. Though there are many variables and aspects that certainly could and likely have contributed to the improvements in pediatric SVT ablation, which this study acknowledges but did or could not specifically evaluate (including variables such as the use of cryoablation and operator experience), we can make many inferences with regards to how 3-dimensional EAM systems contributed to the trends seen. Precise catheter tip tracking and the ability to mark and tag important anatomic structures as well as location of ablation lesions would be expected to improve the precision of ablation and decrease the risk of ablation-associated AV block (which was the most common complication seen). The authors also pointed out the finding of more RF ablation lesions delivered on average in the CAREF group compared to the PAPCA group (12.9 vs. 7.6), noting that this may reflect reduced operator confidence in 3-dimensional EAM. However, combining this study’s data with that from Dionne et al1, it is possible that the higher number of lesions reflects consolidation lesions, which likely contributes to higher success, which was shown in the current study, and lower recurrence as seen in the study by Dionne et al. Taken collectively, these studies provide data for consideration in creating an updated contemporary benchmark for safety and outcomes of pediatric SVT ablation.
Reference: 1 Risk Factors for Early Recurrence Following Ablation for Accessory Pathways. Dionne A et al. Circulation: Arrhythmia and Electrophysiology. 2020; 13(11). DOI:10.1161/circep.120.008848.