Sex differences in outcome after implantable cardioverter defibrillator implantation in nonischemic cardiomyopathy.
BACKGROUND
Women have been underrepresented in randomized trials of implantable cardioverter defibrillator (ICD) therapy, and limited data suggest that women may not benefit from prophylactic ICD implantation to the same extent as men. In the Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial, a reduction in all-cause mortality was seen in men (P = .018) but not for women (P = .76).


METHODS
Sex-specific cumulative probabilities of event-free survival from total, arrhythmic, and noncardiac mortality as well as appropriate shocks were calculated, and log-rank tests were performed. Interaction terms in multivariable Cox proportional hazards models were used to test the hypothesis that the effectiveness of the ICD differed between men and women.


RESULTS
Among 458 patients (326 men and 132 women) with nonischemic cardiomyopathy enrolled in the DEFINITE trial, the test for an interaction between sex and ICD treatment on total mortality was not significant in unadjusted (P = .11) or in multivariable adjusted (P = .18) analyses. When we examined cause-specific mortality, we found no sex difference in the incidence of arrhythmic death. Instead, we documented a relative excess of noncardiac death among women randomized to the ICD (P = .02) as compared with women randomized to standard medical therapy. With respect to device use, there was a trend for women to have fewer appropriate ICD shocks after multivariable adjustment (P = .06).


CONCLUSIONS
Among patients with nonischemic cardiomyopathy enrolled in DEFINITE, we found no conclusive evidence for a sex difference in the effectiveness of the ICD; however, the trial was not adequately powered to detect such interaction effects. Larger studies are required to definitively address whether the benefit of ICD therapy differs between men and women.
Albert
Christine M
CM
Center for Arrhythmia Prevention, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02215-1204, USA. calbert@partners.org
Quigg
Rebecca
R
Saba
Samir
S
Estes
N A Mark
NA
Shaechter
Andi
A
Subacius
Haris
H
Howard
Adam
A
Levine
Joseph
J
Kadish
Alan
A
D009202:Cardiomyopathies / Q000150:complications / Q000401:mortality / Q000628:therapy*; D017147:Defibrillators, Implantable; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000209:etiology / Q000628:therapy; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012737:Sex Factors; D018487:Ventricular Dysfunction, Left / Q000209:etiology