Women are underrepresented in primary prevention implantable cardioverter-defibrillator (ICD) trials, and data on the benefit of ICD therapy in this subgroup are controversial.

The purpose of this study was to better evaluate the benefit of prophylactic ICD in women by performing a meta-analysis of primary prevention ICD trials that assessed gender differences on the end-points of total mortality, appropriate ICD intervention, and survival benefit of ICD compared with placebo.

PubMed, CENTRAL, and other databases were searched in October 2009. Studies were included only if they examined gender differences in the specified end-points, providing the hazard ratio (HR) obtained in multiple Cox regression analyses, and adjusted for all confounding variables.

We retrieved five studies (MADIT-II, MUSTT, SCD-HeFT, DEFINITE, COMPANION) that enrolled 7,229 patients (22% women) with dilated cardiomyopathy (74% ischemic). Compared to men, women had no significant difference in overall mortality (HR 0.96, 95% confidence interval [CI] 0.67–1.39, P = .84) but experienced significantly less appropriate ICD interventions (HR 0.63, 95% CI 0.49–0.82, P ≤.001). The benefit of ICD on mortality was significantly higher in men (HR 0.67, 95% CI 0.58–0.78, P <.001) but did not reach statistical significance in women (HR 0.78, 95% CI 0.57–1.05, P = .1).

Women enrolled in primary prevention ICD trials have the same mortality compared to men while experiencing significantly less appropriate ICD interventions, thus suggesting a smaller impact of sudden cardiac death on overall mortality in women with dilated cardiomyopathy. These findings may explain the smaller ICD survival benefit among women.