Sex differences among subcutaneous defibrillator (S-ICD) recipients: a propensity-matched, multicenter, international analysis from the i-SUSI project.

BACKGROUND AND AIMS: Women have been historically underrepresented in implantable cardioverter defibrillator (ICD) trials. No data on sex differences regarding subcutaneous-ICDs (S-ICD) carriers have been described. Aim of our study was to investigate sex-related differences among unselected S-ICD recipients.

METHODS: Consecutive patients enrolled in the multicenter, international i-SUSI registry were analyzed. Comparisons between sexes were performed using a 1:1 propensity matching adjusted analysis for age, body mass index (BMI), left ventricular function and substrate. The primary outcome was the rate of appropriate shocks during follow-up. Inappropriate shocks and other device-related complications were deemed secondary outcomes.

RESULTS: A total of 1698 patients were extracted from the iSUSI registry; 399 (23.5%) were females. After propensity matching, two cohorts of 374 patients presenting similar baseline characteristics were analyzed. Despite similar periprocedural characteristics and a matched BMI, women resulted at lower risk of conversion failure as per PRAETORIAN score (73.4% vs 81.3%, p = 0.049). Over a median follow-up time of 26.5 [12.7-42.5] months, appropriate shocks were more common in the male cohort (rate/year 3.4%vs1.7%; log-rank p = 0.049), while no significant differences in device-related complications (rate/year: 6.3% vs 5.8%; log-rank p = 0.595) and inappropriate shocks (rate/year: 4.3%vs3.1%; log-rank p = 0.375) were observed. After controlling for confounders, sex remained significantly associated with the primary outcome (aHR 1.648; CI 0.999-2.655, p = 0.048), while not resulting predictor of inappropriate shocks and device-related complications.

CONCLUSION: In a propensity-matched cohort of S-ICD recipients, women are less likely to experience appropriate ICD therapy, while not showing higher risk of device related-complications.