Women in primary prevention implantable cardioverter-defibrillator (ICD) trials have the same overall mortality as men, while experiencing significantly less appropriate ICD interventions, according to a meta-analysis of five randomized studies published in this month’s Heart Rhythm Journal.
Pasquale Santangeli, MD, from the cardiology department at Catholic University in Rome, and colleagues designed the study to evaluate primary prevention ICD trials that assessed gender differences with the end points of total mortality, appropriate ICD interventions and survival benefits compared to placebo.
The meta-analysis included 7,229 patients—1,600 of whom were women—with dilated cardiomyopathy—enrolled in five different studies: MADIT-II, MUSTT, SCD-HeFT, DEFINITE and COMPANION. To ensure direct comparisons between women and men, analysis for each study was adjusted for the maximum number of confounding factors and covariates to provide approximations that would be affected the least by standard gender differences.
The researchers found that women had the same overall mortality as men (hazard ratio 0.96). However, women experienced significantly less ICD interventions on rapid sustained ventricular tachycardia or fibrillation than men (hazard ratio 0.63), suggesting that women are less likely to suffer from sudden cardiac death (SCD).
Additionally, among men ICD therapy was associated with a 33 percent reduction of total mortality compared to the placebo group, while women had a smaller and non-significant reduction of mortality, they found.
“Our main focus was to compare women to men when it came to clinical outcomes following prophylactic ICD placement to determine if certain subgroups of patients should be treated differently,” said Santangeli. “[O]ur findings may explain why women have a smaller and non-significant survival benefits from prophylactic ICD therapy and the importance for further studies to be done on this underrepresented subgroup – women.”
The authors concluded that their findings “challenge” current left ventricular ejection fraction-based prophylactic ICD recommendations, “raising concerns about the appropriateness of generalizing such recommendations to subgroups of patients underrepresented in primary prevention ICD trials and call for further studies, with appropriate economic and social analyses, to determine the cost effectiveness of this therapy in women.”
Also, Santangeli and colleagues suggested that women should be considered more often in trials to continue discoveries for the best outcomes and preventive measures for each gender.