3878Subcutaneous versus transvenous implantable defibrillator therapy: A meta-analysis of case-control studies

Background: The subcutaneous ICD (S-ICD) was developed to minimize complications related to conventional transvenous ICD (TV-ICD). Direct comparison of clinical outcomes between the two devices has been limited by varying patient characteristics and definitions of complications with no randomized trials completed comparing these systems. Purpose: To overcome this paucity in the current literature, we conducted the first meta-analysis to summarize and compare clinical outcomes between S-ICD and TV-ICD. Methods: We systematically reviewed studies in PUBMED, EMBASE databases and secondary referencing sources. Studies meeting criteria were included in the meta-analysis. Baseline characteristics and outcome data of both S-ICD and TV-ICD groups were appraised and analyzed. A random-effects model was used to derive odds ratio (OR) with 95% confidence interval. Results: Six studies met inclusion criteria. Baseline characteristics were similar between the S-ICD and TV-ICD groups. Lead complications were less in the S-ICD group compared to the TV-ICD group (OR 0.13 [0.05,0.34]). The infection rate was similar between the S-ICD and TV-ICD group (OR 0.66 [0.27, 1.60]). There were no differences in system or device failures between groups (OR 0.94 [0.37, 2.41]). Overall, inappropriate therapy (T-wave over-sensing, SVT, episodes of inappropriate sensing) was similar between the two groups (OR 0.81 [0.48,1.36]). However, the nature of inappropriate therapy was different between the S-ICD and the TV-ICD groups. Inappropriate therapies in the TV-ICD group were primarily due to supra-ventricular tachycardia (SVT); whereas inappropriate shocks in S-ICD were mostly episodes of over-sensing (sensing of noise, T-wave over-sensing). Both devices appear to perform equally well with respect to appropriate shocks.