Long-term outcomes associated with subcutaneous implantable cardioverter-defibrillators in patients with hypertrophic cardiomyopathy

Abstract Background In patients with Hypertrophic Cardiomyopathy (HCM) S-ICD is usually the preferred option as pacing is generally not indicated. However, limited data are available on its current practice adoption and long term follow-up. Purpose The present study was designed to examine in a multicenter, open-label, long-term study, the patient’s selection process for S-ICD implantation, the short and long term complications, the appropriate shock (AS) rates, shock efficacy and outcome. Methods Consecutive HCM patients with an S-ICD implanted between 2013 and 2021 in 3 international centers were enrolled in this prospective observational study. Baseline, procedural and follow-up data together with clinical evaluation, ECG, echocardiography, and telemetry checks of the S-ICD were regularly collected. Results Seventy patients (64% males) were enrolled, implanted at 41±15 years, 62 (89%) in primary prevention with a mean ESC SCD risk score of 4,5±1.9%: 25 (40%) at low risk, 17 (27%) at intermediate and 20 (33%) at high risk. Patients were followed-up for 5.1±2.3 years (327 person-years). Notably, 25 (36%) were followed for more than 6 years up to 10 years. Two patients (3%) received an appropriate shock on ventricular fibrillation and 17 (24%) were diagnosed with a de-novo atrial fibrillation, sub-clinical in 6 (9%). One TIA and 2 strokes were reported. Inappropriate shocks occurred in 4 patients (6%), all before Smart-Pass algorithm implementation. Eight patients experienced device related adverse events (11%). Conclusions S-ICDs in HCM patients followed for over 5 years showed to be effective in the conversion of VF in 2 ESC SCD high risk patients (3%) and useful in the detection of sub-clinical AF in 6 (9%). S-ICDs are implanted in patients with an overall low-intermediate ESC SCD risk, probably reflecting both the inclusion of additional risk markers (i.e extensive LGE, reduced EF and apical aneurism) and the physician perception of low device-related complications S-ICD is generally safe, but greater scrutiny may be required to avoid overtreatment in HCM patients with milder risk profiles.Real world use and candidacy of S-ICDAppropriate and inappropriate shocks