Abstract 3630: Sex Differences in the Characteristics of Patients Receiving ICD Therapy for Primary Prevention
Background: Prior studies suggest that women are less likely than men to be referred for ICD implantation for the primary prevention of sudden cardiac death. We hypothesized that women who undergo primary prevention ICD implantation would be more likely to meet strict evidence-based criteria for this therapy.
Methods: We studied 59,833 patients in the NCDR ICD national registry who underwent first-time primary prevention ICD placement between January 2005 and April 2007. Patients were classified according to whether or not they met enrollment criteria of either of two primary prevention trials (MADIT-II: prior MI, LVEF ≤ 30% and MI>40 days or SCD-HeFT: prior heart failure; LVEF≤ 35%, and NYHA class II or III, unless receiving a biventricular pacemaker/ICD (BiV ICD), in which case NYHA IV was considered acceptable). Multivariable analyses assessed the association between sex and concordance with trial enrollment criteria after adjustment for demographic, clinical and health system characteristics.
Results: Among the primary prevention cohort, 27% (n=16,079) were women. Compared with men, women were more often non-white (23.5% vs. 16.8%, p<0.01) had higher NYHA classifications (62.9% vs. 54.7% in class III or IV, p<0.01), and more frequently had a history of heart failure (88.3% vs. 83.2%, p<0.01) and non-ischemic cardiomyopathy (47.0% vs. 28.1%, p<0.01). Women were also more likely to receive a BiV ICD than men (49.4% vs. 42.2%, p<0.01). Overall, 86.1% of women and 85.6% of men met the major primary prevention trials enrollment criteria (p=0.08). Men more often failed to meet trial criteria due to LVEF above cutoff (9.5% vs. 6.7%, p<0.01) or having an MI≤ 40 days before implant (5.7% vs. 4.5%, p<0.01). In multivariable analyses, women were significantly more likely to meet either trial enrollment criteria (OR 1.09, 95% CI 1.03–1.15) than men.
Conclusions: In a large national registry of patients undergoing primary prevention ICD implantation, women were slightly more likely than men to meet the enrollment criteria for MADIT II or SCD-HeFT. As it is not known if patients who fail to meet these criteria benefit from ICD implantation, the implications of this differential pattern of use on outcomes should be investigated.