Long-term outcomes of subcutaneous implantable cardioverter defibrillators: the French nationwide HONEST study

Although use of the subcutaneous implantable cardioverter defibrillator (S-ICD) is increasing, evidence from industry-independent and unselected populations remains limited.

HONEST is a ongoing nationwide academic observational study enrolling 98.2% of patients implanted with an S-ICD across France (2012–2019). Five-year clinical endpoints were centrally adjudicated.

Overall, 4924 patients were enrolled (mean age 49.9 ± 15 years, 76.7% male, 63.0% for primary prevention). Implants used general anaesthesia (78.9%), and defibrillation testing (82.6%). Perioperative complications (within 30 days) occurred in 4.4%. At 5 years, cumulative incidence rates were 13.8% for inappropriate shocks, 10.8% for early battery depletion, 2.4% for infections, 1.5% for lead dysfunction, and 1.4% for chronic discomfort. Reoperation was required in 16.9%, need for cardiac pacing in 3.1%, and definite S-ICD extraction in 8.4%. Inappropriate shocks were independently associated with male sex (hazard ratio [HR] 1.29, 95% confidence interval [CI] 1.14–1.46, P < .001), obesity (HR 1.35, 95% CI 1.02–1.79, P = .032), arrhythmogenic right ventricular cardiomyopathy (HR 1.70, 95% CI 1.03–2.81, P = .036), and the presence of a pacemaker (HR 2.20, 95% CI 1.16–4.17, P = .016). SMART Pass filtering significantly reduced inappropriate shocks (HR 0.67, 95% CI 0.50–0.89, P = .007). Among patients with inappropriate shocks, ∼1% developed induced ventricular fibrillation (one fatality), and 10% underwent device extraction. Ineffective shocks or undetected arrhythmias occurred in only 0.2%. Among 547 deaths (11.1%), 53.9% were cardiovascular, including 26 sudden deaths, and 8 were S-ICD/procedure-related, with none related to S-ICD extraction.

This nationwide study refines the long-term event profile of S-ICD therapy and may inform clinical practice and device selection.