# Is Resynchronization Pacing Proarrhythmic Among Congenital Heart Patients? An Evaluation and Review

## TL;DR

This study examines whether cardiac resynchronization therapy increases arrhythmia risk in congenital heart disease patients over 20 years.

## Contribution

The study provides long-term evidence on CRT safety in CHD patients, addressing a gap in understanding proarrhythmic risks in younger populations.

## Key findings

- CRT improved 10-year survival free from death or heart transplant compared to medical management.
- No new-onset arrhythmias were observed in either CRT or medical management groups.
- Pre-existing arrhythmias were linked to adverse outcomes in some CRT recipients.

## Abstract

Background: Cardiac resynchronization therapy (CRT) can be an effective form of heart failure (HF) management among congenital heart disease (CHD) patients (pts) with and without surgically repaired defects. However, very long-term results are limited. Recently, CRT has been implicated to be proarrhythmic among older CRT recipients. This issue is largely unknown among younger CHD-CRT pts. This study presents up to a 20-year (y) continuous review of any arrhythmia (Arr) burden associated with CRT among CHD-HF pts. Methods: From 1999 to 2024, outcomes of 45 CHD-HF pts (NYHA II-IV) (age 4–57 y [mean 26]; 31% female) were compared between those on established medical management (MM) (n = 18) and CRT recipients (n = 27) followed continuously for 1–20 years. Pre-existing and any de novo Arr that occurred following CRT were documented. Clinical assessments were continuous. Results: Follow-up was for 1 to 20 y (mean 7.5 y ± 0.7 sem). Patient demographics (CRT vs. MM groups) were comparable. Pre-existing Arr were found in 16 pts (38%) from both groups: accelerated junction (one CRT), atrial flutter (one CRT; two MM), and ventricular tachycardia (six CRT; six MM). During follow-up, outcomes included 14 pt deaths and 7 heart transplants (HTs). Of these, pre-existing Arr were causative among three CRT recipients: two ≤ 2 y and one > 5 y after CRT. There were no new-onset Arr in any pt groups. CRT significantly improved patient survival free from HT or death at 10 y (44 vs. 13% [p < 0001]). Conclusion: When applied effectively, CRT benefits CHD-HF pts without causing additional arrhythmias. However, pre-existing Arr remain a concern reflecting persistently adverse intrinsic myocellular issues among CHD-HF pts.