BACKGROUND The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to defibrillate ventricular arrhythmias, avoiding drawbacks of transvenous leads. The global EFFORTLESS S-ICD (Evaluation oF FactORs ImpacTing CLinical Outcome and Cost EffectiveneSS of the S-ICD) registry is collecting outcomes in 985 patients during a 5-year follow-up.
OBJECTIVES The primary goal of the EFFORTLESS registry is to determine the safety of the S-ICD by evaluating complications and inappropriate shock rate.
METHODS This is the first report on the full patient cohort and study endpoints with follow-up $1 year. The predefined endpoints are 30- and 360-day complications, and shocks for atrial fibrillation or supraventricular tachycardia. RESULTS Patients were followed for 3.1 ± 1.5 years and 82 completed the study protocol 5-year visit. Average age was 48 years, 28% were women, ejection fraction was 43 ± 18%, and 65% had a primary prevention indication. The S-ICD system and procedure complication rate was 4.1% at 30 days and 8.4% at 360 days. The 1-year complication rate trended toward improvement from the first to last quartile of enrollment (11.3% [quartile 1]) to 7.8% [quartile 2], 6.6% [quartile 3], and 7.4% [quartile 4]; quartile 1 vs. quartiles 2 to 4; p ¼ 0.06). Few device extractions occurred due to need for antitachycardia (n ¼ 5), or biventricular (n ¼ 4) or bradycardia pacing (n ¼ 1). Inappropriate shocks occurred in 8.1% at 1 year and 11.7% after 3.1 years. At implant, 99.5% of patients had a successful conversion of induced ventricular tachycardia or ventricular fibrillation. The 1- and 5-year rates of appropriate shock were 5.8% and 13.5%, respectively. Conversion success for discrete spontaneous episodes was 97.4% overall.
CONCLUSIONS This registry demonstrates that the S-ICD fulfills predefined endpoints for safety and efficacy. Midterm performance rates on complications, inappropriate shocks, and conversion efficacy were comparable to rates observed in transvenous implantable cardioverter-defibrillator studies.

Additional Metadata
Keywords appropriate therapy, inappropriate therapy, leadless, primary prevention, secondary prevention, ventricular arrhythmias
Persistent URL,
Journal Journal of the American College of Cardiology
Note on behalf of the EFFORTLESS Investigator Group
Boersma, L, Barr, C.S, Knops, R.E, Theuns, D.A.M.J, Eckardt, L, Neuzil, P, … Lambiase, P.D. (2017). Implant and Midterm Outcomes of the Subcutaneous Implantable Cardioverter-Defibrillator Registry. Journal of the American College of Cardiology, 70(7), 830–841. doi:10.1016/j.jacc.2017.06.040