Background: Implantable cardioverter defibrillators (ICDs) are essential for preventing sudden cardiac death (SCD) from ventricular arrhythmias. However, inadequate ICD-therapies (i-ICD-T) due to supraventricular arrhythmias can occur, in which case catheter ablation (CA) may be considered. However, data for CA after i-ICD-T are scarce.

Aim: The aim of this study was to investigate the outcome of CA of supraventricular arrhythmias in ICD-carriers, who experienced prior i-ICD-T, and to identify predictors of i-ICD-T.

Methods: We retrospectively analyzed consecutive ICD, cardiac resynchronization therapy-defibrillator (CRT-D) and subcutaneous ICD (s-ICD)-carriers undergoing CA for supraventricular arrhythmias {atrial fibrillation (AF), atrial tachycardia (AT), atrial flutter (AFlut) and AV-node-reentry-tachycardia (AVNRT)}, including patients with i-ICD-T and without prior inadequate ICD-therapies (non-i-ICD-T), from 06/2017 until 09/2024 in a single center. The primary endpoint was reduction of i-ICD-T during follow up (FU).  Secondary endpoints were predictors of i-ICD-T, arrhythmia-free survival and procedural safety of CA.  

Results: A total of 128 ICD-carriers {n=91/128 (71.1%) ICD, n=35/128 (27.3%) CRT-D and n=2/128 (1.6%) s-ICD} were analyzed {age 65.3 ± 12 years, left ventricular ejection fraction 40.7 ± 11.8%, n=54/128 (42.2%) ischemic cardiomyopathy, n=44/128 (34.4%) dilated, n=11/128 (8.6%) hypertrophic, n=2/128 (1.6%) Brugada, n=1/128 (0.8%) long-QT n=4/128, (3.1%) inflammatory, n=2/128 (1.6%) catecholaminergic, n=10/128 (7.8%) unknown}. Of the complete cohort, prior to CA n=24/128 (18.7%) patients suffered from i-ICD-T {83%, n=20/24 anti-tachycardia pacing (ATP) + ICD-shocks, 27% n=4/24 ICD-shock only} and 104/128 (81.3%) patients had non-i-iCD-T. Distribution of supraventricular arrhythmias and ablation strategy are shown in Table 1. After a median FU of 35 months (interquartile range 8 to 49), CA reduced i-ICD-T significantly {n=24/24, 100% prior to CA to n=2/24, 8.3% (n=2/2 ATP + shock) p< 0.0001} in the i-ICD-T-group. In the non-i-ICD-T-group, no patient suffered an i-ICD-T during FU. Paroxysmal AF was identified as the only predictor for i-ICD-T in ICD-carriers prior to CA (odds ratio 9, p<0.0001). The overall arrhythmia-free survival at one year was 72.6% (75% in the i-ICD-T-group and 72.1% in the non-i-ICD-T-group, p=0.8). The procedural complication rate was 3.1% {n=1/128 (0.8%) groin complication, n=1/128 (0.8%) tamponade and n=2/128 (1.6%) device-related complications}.    

Conclusion: CA of supraventricular arrhythmias in ICD-carriers results in successful reduction of inadequate ICD-therapies, acceptable rhythm control and procedural safety. The only predictor identified for inadequate ICD-therapies was paroxysmal AF. 

TABLE 1: Underlying supraventricular arrhythmias and CA strategy.

CTI, cavotricuspid isthmus ablation; PVI, pulmonary vein isolation;