Efficacy And Safety Of The Subcutaneous Implantable Cardioverter Defibrillator: A Systematic Review

Background: Subcutaneous implantable cardioverter defibrillators (S-ICD) are an alternative to conventional transvenous implantable cardioverter defibrillators (TV-ICD) in patients not requiring pacing. We sought to define the efficacy and safety of S-ICD through literature review.
Methods: We searched MEDLINE and EMBASE for studies evaluating efficacy and safety outcomes among patients undergoing S-ICD implantation. We performed narrative synthesis and pooled efficacy and safety outcomes across studies.
Results: 16 studies were included with 5,380 participants (mean age range 33–56 years). Short-term follow-up data were available for 1670 subjects. The commonest complication was pocket infection, affecting 2.7% (range 0–19%). Other complications included delayed wound healing (0.6%), wound discomfort (0.8%), haematoma (0.4%) and lead migration (0.3%). A total of 3.8% (range 0–12%) of S-ICDs were explanted. The commonest reason for explant was pocket infection. Mortality rates in hospital (0.4%) and during follow-up (3.4% from 12 studies reporting, 2.1% per person-years) were low. The number of patients experiencing ventricular arrhythmia varied from 0 to 12%. Overall shock efficacy for treatment of ventricular arrhythmias exceeded 96%. Inappropriate shocks affected 4.3% (range 0–15%) of patients and was most commonly caused by T-wave oversensing.
Conclusions: Although long-term randomised data are lacking, observational data suggest shock efficacy, peri-procedural and short-term complication rates of the S-ICD are similar to TV-ICD, making the S-ICD a suitable alternative in patients without an indication for pacing.