The Subcutaneous Implantable Cardioverter Defibrillator (S-ICD) has emerged as a promising tool in preventing sudden cardiac death, with fewer complications reported in industry-supported trials from experienced centers. Nonetheless, its broader applicability and long-term real-world outcomes warrant comprehensive evaluation.

The study aimed to provide independent long-term S-ICD outcomes.

The HONEST study, a nationwide observational study, enrolled all patients receiving S-ICDs in France between 2012 and 2019. These patients are followed by telecardiology and routine clinical follow-ups, with meticulous event adjudication.

Out of 5015 patients implanted with S-ICD in France, 4924 (98.2%) were enrolled in the study (mean age 49.9±15.0 years, 23.31% females, 21.79% with electrical heart disease, 36.7% for secondary prevention, mean left ventricular ejection fraction 42.3±16.8%). The cumulative incidence of appropriate shocks increased from 5.10% in the first year to 14.62% by the fifth year (Fig. 1). Early (within 30 days) post implant complications occurred in 3.61%, mainly local complications: infections (0.72%), pocket hematomas (0.94%), and poor wound healing (0.48%). One-year and five-year rates of complications escalated from 9.45% to 27.06% respectively, including inappropriate shocks (5.05% to 13.79%), infection (1.77% to 2.40%), Lead issues (0.21% to 1.47%), premature battery depletion (0.35% to 8.76%), and chronic discomfort (0.28% to 1.42%). Implantation of a pacing system was necessary in 3.09% at 5 years. Definitive S-ICD removals rose to 8.24% by the fifth year, predominantly due to complications, pacing needs, and heart transplant. Among the 547 deaths in the cohort, 51.74% were cardiovascular-related, with 8 directly associated with S-ICD complications and 23 cases of unexplained sudden cardiac deaths.

The HONEST study advocates for the S-ICD's broader applicability and emphasizes a personalized approach to optimize outcomes.