The American team analyzed 19,710 medical records to draw their conclusions. In this group of patients, women accounted for almost 80 percent of heart failure patients in which left ventricular systolic function was preserved.

Frederick Masoudi, M.D., lead author of the study, said that recognition of the gender difference in rates of preserved left ventricular systolic function is important for both clinical and research reasons. "There are fairly dramatic implications in terms of treatment," he said. "If we are going to try to make sure that we have an evidence base of treatment that is applicable to a wide range of patients, both men and women, future research really does need to address this issue and look at treatment strategies in [female] patients with heart failure and preserved systolic function."

However, Masoudi also cautioned that gender cannot be used to predict which type of heart failure an individual patient may have. Because the clinical symptoms are similar, testing is required to determine whether the defect in pump function is related to impairment in left ventricular ejection fraction or in diastolic relaxation and filling.

Although the current study is not the first to link preserved left ventricular systolic function and gender, this analysis stands out from earlier work both in terms of the size of the patient population studied and the sophistication of statistical analysis. Masoudi noted that the analysis indicates gender correlation was consistent across patient subgroups, including different age brackets and types of comorbid conditions. The finding leaves a key question for future research: What causes women to develop diastolic failure so much more frequently than men?

Barry Massie, M.D., who was not part of the research team, called the findings remarkable. "I believe this is a very important paper," he said. "The prevalence and importance of heart failure in patients with normal systolic function (defined in the article as an ejection fraction of 50 percent or greater) have recently been recognized, but this study adds to our appreciation of this syndrome because of the large size of the population studied. The key point, however, is that to an extent not previously appreciated, heart failure with preserved systolic function is a condition affecting primarily women and more related to female gender than advancing age."