Subcutaneous implantable cardioverter-defibrillator in adults with congenital heart disease

Abstract Background Subcutaneous implantable cardioverter-defibrillators (S-ICD) are an established treatment option for the prevention of sudden cardiac death (SCD). However, data in adults with congenital heart disease (ACHD), especially in direct comparison to other patient groups (e.g. cardiomyopathies) are scarce. Methods Retrospective single-center study of all patients receiving a S-ICD in the time-period 2012-2020. ACHD patients were compared to non-ACHD patients. Primary outcome was all-cause mortality. Secondary outcome was a combined endpoint of all-cause mortality and appropriate shocks. Results Altogether, 79 patients (11 ACHD, 68 non-ACHD patients) with a mean age of 40.6 ± 16.0 years (29.1% female) were included. There was no significant difference for age and sex between both groups. Secondary prevention of SCD was more often the indication for a S-ICD in ACHD (81.8%) than in non-ACHD patients (48.5%; p=0.040). Betablockers were more commonly used in ACHD patients (100% vs. 64.7%; p=0.018). There was no significant difference for other heart failure medications. During a median follow up of 3.4 years [IQR 1.7-5.2], the primary endpoint occurred in 36.4% of ACHD vs. 2.9% of non-ACHD patients (p<0.001). The secondary endpoint occurred also more often in the ACHD patient group compared to non-ACHD patients (54.5% vs. 17.6%, p=0.007). There was a numerically higher number of inappropriate shocks in the ACHD group (27.3% vs. 9.0%), albeit without a statistically significant difference (p=0.078). Conclusions In ACHD patients with a S-ICD, mortality as well as a combined endpoint of mortality and appropriate shocks were more common than in non-ACHD patients. The numerically higher number of inappropriate shocks deserves further attention.