Nearly half of elderly patients who have an ischemic stroke also have atrial fibrillation, based on a review of 527 stroke patients aged 75 or older at a single U.S. center.

Atrial fibrillation (AF) “should be meticulously searched for” in elderly stroke patients who have not already been diagnosed with the arrhythmia so that they can be considered for anticoagulation treatment to prevent future strokes, Dr. Jacob I. Haft and Dr. Louis E. Teichholz said in a poster presentation at the International Stroke Conference.

The findings “suggest that atrial fibriilation plays a more important role in the etiology of stroke than previously considered,” said Dr. Haft and Dr. Teichholz, who are both cardiologists at Hackensack (N.J.) University Medical Center.

The prevalence of AF among elderly stroke patients was even higher among patients with other comorbidities that also predispose to atrial arrhythmia. For example, among the 130 elderly stroke patients studied who also had heart failure, the AF prevalence was 68%. Among elderly patients with a cardiac abnormality detected by echocardiography, the prevalence of AF was 56%. Among the elderly with coronary artery disease, the AF prevalence was 53%, they reported.

In contrast, among 458 stroke patients included in the study who were younger than 75 years old, the AF prevalence was 15%. Gender was not linked to AF prevalence.

The investigators reviewed patients admitted to the medical center from January 2005 to December 2007 with a diagnosis of ischemic stroke and retrospectively diagnosed AF in these patients based on a 14-year database of ECG recordings available at the hospital. Because the AF diagnoses depended on “serendipitous” identification of AF episodes and did not come from a systematic, prospective study, the analysis likely underestimated the true prevalence of AF in these stroke patients, the researchers said at the meeting, which was sponsored by the American Heart Association.

Dr. Haft and Dr. Teichholz said that they had no disclosures.