S‐ICD in Hypertrophic Cardiomyopathy: Fewer Complications Without Increased Inappropriate Shocks Versus Transvenous Systems

Background The subcutaneous implantable cardioverter defibrillators (S‐ICD) in hypertrophic cardiomyopathy (HCM) remains controversial. HCM patients are often younger and exposed to longer‐term risks: complications and inappropriate therapy (IT). The S‐ICD avoids vascular risks associated with transvenous ICDs (TV‐ICD), but the rate of IT remains a concern. We conducted a retrospective observational study in HCM patients who received ICDs: assessing outcomes and utilizing a multi‐event statistical model, we provide a novel assessment of the cumulative complication risk. Methods A retrospective study of all HCM patients who received an ICD at a tertiary center from 2006 to 2022 was conducted, utilizing electronic pacing and health records. Cox‐proportion hazard models were applied for comparative outcome analysis and a multi‐event statistical model was used to assess the cumulative burden of complications. Propensity score matching was used to adjust for baseline differences. Results We analysed data from 611 patients, with 141 receiving S‐ICDs (26.7%). S‐ICD patients had significantly fewer complications over a maximal follow‐up of 137 months (HR 0.309, 95% CI 0.103–0.923, p = 0.035). Multi‐event analysis demonstrated a cumulative increase in complications over time for TV‐ICD patients (HR 0.258, 95% CI 0.109–0.644, p = 0.004), conversely no S‐ICD patients experienced multiple complications. There was no difference in therapy rates or mortality between matched groups. Conclusion The S‐ICD is associated with fewer complications than TV‐ICD, this is amplified by multi‐event analysis, but without differences in IT. This should be discussed with HCM patients, as the S‐ICD could provide a better benefit/risk ratio.