Sudden cardiac death in newly diagnosed non-ischaemic or ischaemic cardiomyopathy assessed with a wearable cardioverter-defibrillator: the German nationwide SCD-PROTECT study

Background and Aims Patients with newly diagnosed non-ischaemic cardiomyopathy (NICM) or myocardial infarction/coronary artery disease (MI/CAD) face an increased risk of sudden cardiac death (SCD) during the early phase of guideline-recommended medical therapy initiation and up-titration. Aim is to evaluate the risk in this population by assessing sudden cardiac arrest (SCA) due to ventricular tachycardia/ventricular fibrillation (VT/VF). Methods All patients in Germany who received a wearable cardioverter-defibrillator (WCD) between December 2021 and May 2023 were enrolled in the observational multicentre SCD-PROTECT study (NCT06883383). The primary outcome was the incidence of SCA due to sustained VT/VF, measured by appropriate WCD-delivered treatments, and reported as events per 100 patient-years with 95% confidence intervals (CI). Secondary outcomes included inappropriate WCD treatments, all-cause mortality, adverse events, adherence to WCD use, and heart failure medication patterns. Results In this cohort of 19 598 patients, the mean age (±standard deviation) was 58.6 ± 13.7 years for those with NICM and 64.2 ± 10.6 years for patients with MI/CAD. Female patients accounted for 23.8% of the NICM and 16.3% of the MI/CAD group. Left ventricular ejection fraction (LVEF) at study start was 26.9 ± 10.3% for NICM and 28.4 ± 8.0% for MI/CAD patients. The incidence rate of first appropriate treatment by WCD in NICM patients and MI/CAD patients was 6.10 (95% CI 5.31–7.00) and 8.64 (95% CI 7.41–10.05) events per 100 patient-years, respectively. Overall incidence density for all appropriate treatments was 8.53 (95% CI 7.36–9.88) and 14.98 (95% CI 12.69–17.65) per 100 patient-years in the respective groups. Improvement in LVEF to >35% was observed in 53.5% of NICM patients and 51.7% of MI/CAD patients over a mean of 65.9 ± 43.8 days. 36.2% of patients were implanted with a cardioverter-defibrillator at the end of WCD use. Total mortality was 0.8%. Inappropriate shocks occurred in 0.5% of patients. Conclusions The SCD-PROTECT study highlights a substantial risk of SCA due to VT/VF during the early phase of guideline-recommended medical therapy optimization in patients with newly diagnosed reduced LVEF, regardless of ischaemic or non-ischaemic origin. The WCD provided SCD protection, the LVEF could improve to >35% in the majority of these patients and can therefore serve as risk stratification across both aetiologies.