Introduction: Gender differences in outcomes after cardiac resynchronization therapy defibrillators (CRT-Ds) have been described in clinical trials, but the influence of gender on CRT-D outcomes in real-world registries is incompletely understood.
Hypothesis: We hypothesized that gender would have a significant effect on overall survival and the survival benefit after CRT-D based on a comparison of patients with and without devices.
Methods: Using the National Cardiovascular Data Registry Version 1 Implantable Cardioverter Defibrillator (ICD) Registry, patients with CRT-Ds were compared with patients with similar degrees of heart failure but without CRT-Ds from other registries and trials. Multivariable Cox proportional hazards regression models were used to assess adjusted associations among covariates of interest.
Results: There were 38,642 patients with CRT-Ds and 507 patients in the control group. Women accounted for 35.5% in the CRT-D group (age 69.6 ± 10.9 years) and 30.0% in the control group (age 71.5 ± 11.3 years). Female gender was associated with improved adjusted survival (adjusted HR=0.82, 95% CI 0.78-0.86, P<0.0001) after CRT-D relative to controls. As shown in the Figure, although women had a better survival overall after CRT-D, the survival benefit with CRT-D compared with controls was at least as good in men. In the Cox proportional hazards models adjusted for heart failure severity using the Seattle Heart Failure Model, the adjusted CRT-D HR in men was 0.57 (95% CI 0.46-0.70, P<0.0001), and the adjusted CRT-D HR in women was 0.74 (95% CI 0.48-1.14, P=0.17).
Conclusions: While female gender was associated with improved survival after CRT-D implantation, the overall survival benefit after CRT-D in men was at least as great as that in women. These observations are likely mediated by independent effects from the defibrillator and resynchronization pacing components of CRT-Ds.