Gender differences in risk of sudden cardiac arrest in patients with newly diagnosed non-ischemic cardiomyopathy or coronary artery disease: targeted insights from the SCD-PROTECT study

Background A significant risk of sudden cardiac death (SCD) in patients with newly diagnosed cardiomyopathy with reduced left ventricular ejection fraction (LVEF) was revealed by the SCD-PROTECT study. Purpose This exploratory sub-group analysis of the SCD-PROTECT study aimed to assess gender differences in baseline and outcome data. Methods The SCD-PROTECT study included all patients in Germany who received a wearable cardioverter-defibrillator (WCD) between December 2021 and May 2023 due to non-ischemic cardiomyopathy (NICM) or myocardial infarction / coronary artery disease (MI/CAD). The primary endpoint of the SCD-PROTECT study was the incidence of SCA due to sustained ventricular arrhythmias and was evaluated according to gender in this sub-analysis. It was measured by appropriate treatments delivered by a WCD and reported as events per 100 patient-years. Secondary endpoints included inappropriate WCD treatments, all-cause mortality, adverse events, adherence to WCD use, and heart failure medication patterns. Results Out of 19,598 patients enrolled in the SCD-PROTECT study, 4,053 (20.7%) were women, 11,449 patients (female 23.8%) with NICM and 8,149 patients (female 16.3%) with MI/CAD. Baseline characteristics, arrhythmias during hospital stay, and medication at hospital discharge stratified by gender are presented in Table 1. The incidence rate of the first appropriate treatment in the total group was 6.01 (95%CI: 4.37-8.07) per 100 patient-years for women and 7.43 (95%CI: 6.46-8.52) per 100 patient-years for men (gender difference: p=0.19). In the NICM group it was 4.60 (95%CI: 2.92-6.90) per 100 patient-years for women and 6.57 (95%CI: 5.37-7.96) per 100 patient-years for men (p=0.15), and in the MI/CAD group 9.04 (95%CI: 5.60-13.82) per 100 patient-years in women and 8.56 (95%CI: 7.0-10.38) per 100 patient-years in men (p=0.81). The overall incidence density of appropriate treatments in the total group was 9.69 (95%CI: 7.57-12.22) per 100 patient years for women and 11.56 (95%CI: 10.34-12.89) per 100 patient-years for men (p=0.21). In the NICM group it was 6.60 (95%CI: 4.54-9.27) per 100 patient-years for women and 9.14 (95%CI: 7.71-10.75) per 100 patient-years for men (p=0.10), and in the MI/CAD group 16.36 (95%CI: 11.58-22.45) per 100 patient-years in women and 14.72 (95%CI: 12.64-17.04) per 100 patient-years in men (p=0.58). Improvement in LVEF to >35% was observed in 65.4% of women and 63.1% of men in the NICM group, resp. 64.0% of women and 61.0% of men in the MI/CAD group. Median daily wear-time was 23.3-23.7 hours a day. Inappropriate shocks occurred in 0.3% of women and 0.6% of men. During the observation period 0.5% of women and 0.9% of men died. Conclusion For both women and men with newly diagnosed NICM or MI/CAD and reduced LVEF the risk of SCD is substantial. No statistically significant differences between genders could be found. Therefore, the WCD should be used equally in both genders.Figure 1Figure 1