Doctors can see how well the left ventricle works by measuring the ejection fraction, which is the percentage of blood squeezed out of the ventricle with each heartbeat. An ejection fraction of 50 percent means the ventricle spurts out half its volume each time it contracts.

Healthy ejection fractions are 50 percent or higher; lower ejection fractions can mean heart disease. But patients may have normal ejection fractions and still have serious heart problems such as severe mitral regurgitation.

In the study, 32 percent of 869 participating mitral regurgitation patients were on a beta-blocker. Beta-blockers reduce the heart rate and the force of muscle contraction, thereby reducing oxygen demand on heart muscle.

The researchers found that beta-blockers increased patients' survival, independent of patients' age, gender, or whether they had coronary artery disease, diabetes, high blood pressure or valve surgery.

In a related poster, researchers showed the drugs' benefits to patients with diastolic heart failure-those with congestive heart failure, or CHF, who have normal ejection fraction.

Researchers studied 2,246 patients with CHF; 1,079 of them had normal ejection fractions. The patients were on a variety of CHF therapy regimens, which might include aspirin, diuretics, digoxin, ACE inhibitors and beta-blockers.

Beta-blockers were once thought risky for heart-failure patients. But the investigators found that after five years, 65 percent of patients treated with beta-blockers were alive, compared to 50 percent of those who received no beta-blockers. Beta-blocker therapy still showed a strong survival benefit after researchers adjusted for patients' age, gender, hypertension, diabetes and coronary artery disease.

Ramdas G. Pai, M.D., professor of clinical cardiovascular medicine at the Keck School and the study's senior author, explained that catecholamines-the hormones released in the body in stress s
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Contact: Sarah Huoh
shuoh@usc.edu
323-442-2830
University of Southern California
7-Mar-2005