Some Heart Failure Patients Don't Benefit From Treatment With Angiotensin II Receptor Blocker
An angiotensin II receptor blocker was no better than usual care for a type of heart failure that mostly affects women and the elderly, researchers reported at the American Heart Association's Scientific Sessions 2008. Irbesartan in Heart Failure with Preserved Systolic Function (I-PRESERVE) was presented as a late-breaking clinical trial. The study was simultaneously published in the New England Journal of Medicine.
The major finding most people associate with a failing heart is a reduced ability to pump blood, called a low ejection fraction, said Barry M. Massie, M.D., co-principal investigator of the study, professor of medicine at the University of California, San Francisco and chief of the cardiology division at the San Francisco Veterans Administration Medical Center. But patients can also have heart failure with good heart pumping ability, a situation referred to as "preserved ejection fraction heart failure."
The world's largest placebo-controlled trial of an angiotensin II receptor blocker (ARB) in this syndrome included 4,128 participants (average age was 72, 60 percent were women) who were randomized to receive either irbesartan, an ARB currently used to treat blood pressure, or usual care for preserved ejection fraction heart failure. Researchers then followed them for 4.5 years to assess clinical outcomes.
"Typically, the public and physicians think of heart failure as a large, poorly contracting heart that can't pump adequate blood to the rest of the body with an ejection fraction of under 35 percent," Massie said. "But up to half of all heart failure patients have normal or preserved ejection fractions. Their hearts pump well and are not enlarged yet these patients still have the classic heart failure symptoms of fluid retention, shortness of breath and edema or swelling."
Compared to patients with low ejection fraction heart failure, those with preserved ejection fraction are older, more often women and are more likely to have high blood pressure. In this study, more than a third of participants were over age 75 and investigators reported high blood pressure as a heart failure cause in 64 percent of patients. The average of their ejection fraction was 59 percent.
Earlier studies suggested that patients with preserved ejection fraction heart failure may fare better on ARBs or ACE inhibitors than on conventional treatment but their results were not statistically significant, said Peter E. Carson, M.D., co-principal investigator, associate professor of medicine at Georgetown University and chief of the coronary care unit of Washington Veterans Administration Medical Center in Washington D.C.
In I-PRESERVE the primary outcome - a composite of all-cause death, hospitalization for heart failure, heart attack, unstable angina, arrhythmia and stroke - occurred in 742 people in the irbesartan group and 763 in the placebo group, a difference that was not statistically significant. Two major secondary endpoints, cardiovascular death and death or hospitalization specifically due to heart failure, were also not different between the treatment and control groups.
I-PRESERVE researchers found that the ARB was safe and well-tolerated, indicating that it could be a substitute for patients unable to tolerate other high blood pressure drugs.