OBJECTIVES This study was designed to determine if women are more likely than men to have heart failure (HF) with preserved systolic function after adjustment for potential confounders, including age.   
 BACKGROUND Although prior evidence suggests an independent association between female gender and preserved left ventricular systolic function (LVSF) in patients with HF, existing studies are limited by referral biases, small sample sizes, or the inability to adjust for a wide range of potential confounding variables.   
 METHODS This is a cross-sectional study using data from retrospective medical chart abstraction of a national sample of Medicare beneficiaries hospitalized with the principal discharge diagnosis of HF in acute-care nongovernmental hospitals in the U.S. between April 1998 and March 1999. Patients were eligible for this analysis if they were age 65 years or older, had documentation of LVSF, and corroboration of the diagnosis of HF. We used multivariable logistic regression to identify the correlates of preserved LVSF, which was defined as qualitatively normal function or quantitatively reported ejection fraction > or =0.50. Stratified regressions by gender were performed to identify significant interactions.   
 RESULTS Of the 19,710 patients in the analysis, preserved LVSF was present in 6,700 (35%), 79% of whom were women. In contrast, among the 12,956 patients with impaired LVSF, only 49% were women. Patients with preserved LVSF were 1.5 years older than those with impaired LVSF. After adjustment for age and other patient factors, female gender remained strongly associated with preserved LVSF (calculated risk ratio = 1.71; 95% confidence interval 1.63 to 1.78). The association was consistent in all age groups, and was similar in patients with or without coronary artery disease, hypertension, pulmonary disease, renal insufficiency, or atrial fibrillation.   
 CONCLUSIONS In elderly patients hospitalized with HF, preserved systolic function is primarily a condition of women, independent of important demographic and clinical characteristics.
True