Comparative outcomes of subcutaneous and transvenous cardioverter-defibrillators.

Background: The comparative outcomes of subcutaneous implantable cardioverter-defibrillator (S-ICD) and transvenous ICD (T-ICD) have not been well studied. The aim of this study was to evaluate the safety and efficacy of currently available S-ICD and T-ICD. Methods: The study included 86 patients who received an S-ICD and 1:1 matched to those who received single-chamber T-ICD by gender, age, diagnosis, left ventricular ejection fraction (LVEF), and implant year. The clinical outcomes and implant complications were compared between the two groups. Results: The mean age of the 172 patients was 45 years, and 129 (75%) were male. The most common cardiac condition was hypertrophic cardiomyopathy (HCM, 37.8%). The mean LVEF was 50%. At a mean follow-up of 23 months, the appropriate and inappropriate [CD therapy rate were 1.2% vs. 4.7% (chi(2)=1.854, P= 0.368) and 9.3% vs. 3.5% (chi(2)=2.428, P= 0.211) in S-ICD and T-ICD groups respectively. There were no significant differences in device-related major and minor complications between the two groups (7.0% vs. 3.5%, chi(2)=1.055, P=0.496). The S-ICD group had higher T-wave oversensing than T-ICD group (9.3% vs. 0%, chi(2)=8.390, P =0.007). Sixty-five patients had HCM (32 in S-ICD and 33 in T-ICD). The incidence of major complications was not significantly different between the two groups. Conclusions: The efficacy of an S-ICD is comparable to that of T-ICD, especially in a dominantly HCM patient population. The S-ICD is associated with. fewer major complications demanding reoperation.