Primary prevention with defibrillator therapy in women: results from the Sudden Cardiac Death in Heart Failure Trial.

Introduction: The Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) demonstrated that implantable cardioverter defibrillator (ICD) therapy reduced overall mortality in patients with class II or III heart failure and left ventricular ejection fraction (LVEF) <or= 35%, while amiodarone had no effect on survival. There are limited data regarding the influence of gender on outcome of patients receiving ICDs for primary prevention.
Methods: We examined gender differences in response to treatment and outcome in this cohort.
Results: Women comprised 23% of the SCD-HeFT cohort, with similar percentages in the amiodarone, ICD, and placebo groups. Compared with men, women were more likely to be non-Caucasian, to have class III heart failure, and nonischemic heart disease. After adjustment for baseline differences, overall mortality risk was lower in women than in men. The gender difference in overall mortality was seen in the placebo group, while no gender difference in overall mortality was seen in the ICD group. There was a significantly lower absolute risk of death in the placebo arm women, compared with the placebo arm men (annual mortality rate approximately 4% vs. 6%).
Conclusions: The impact of ICD therapy appears to differ between men and women in this trial, with a smaller ICD benefit among women. However, the test for an interaction between gender and therapy was not significant. The lower overall mortality risk in women in the placebo group and the smaller number of women enrolled may help to explain why treatment differences in women were much smaller and difficult to detect.