For a study, researchers intended to identify specific risk factors for ventricular tachyarrhythmia (VTA) in women placed with an implantable cardioverter-defibrillator (ICD) for primary prevention. The study group comprised 4,506 patients who participated in the 4 key MADIT studies – MADIT-II, MADIT-RISK, MADIT-CRT, and MADIT-RIT – with an ICD or cardiac resynchronization therapy-defibrillator (1,075 women [24%]). Female-specific risk variables for the major endpoint of VTA, defined as ICD-recorded, treated, or monitored sustained ventricular tachycardia of more than 170 beats per minute or ventricular fibrillation, were identified using Fine and Gray regression models. At 3.5 years of follow-up, the cumulative incidence of VTA in women was considerably lower than in men (17% vs. 26%, respectively; P<0.001 for the entire follow-up). In women, the use of amiodarone at enrolment, Black race, and a history of previous myocardial infarction without prior revascularization were independent risk factors for VTA. Only the Black race was related to a statistically significant increase in risk among men. At 3.5 years, the cumulative incidence of VTA in women with one or more of these risk factors was 27%, compared to 14% in women without any of these risk factors (hazard ratio [CI]=2.08 [1.49 to 2.91]). In conclusion, the investigation, which consisted of 4 landmark ICD clinical trials, demonstrated that sex and race have the potential to be exploited for enhanced risk classification of ICD primary preventive candidates.

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