ST. PAUL, Minn. -- Two drugs commonly used to treat high blood pressure significantly help prevent future heart attacks, prolong survival in heart-attack patients and reduce the incidence of heart failure, researchers at the University of Minnesota and the Mayo Clinic in Rochester have found.
The findings, contained in two studies published in today's New England Journal of Medicine, are important because heart disease remains America's leading killer. Nationally, nearly 600,000 people die annually from heart attacks and their consequences.
The drugs involved in the studies, captopril and enalapril, belong to a family of drugs called angiotension-converting-enzyme inhibitors. They control blood pressure by interfering with the enzyme system in the body that causes blood vessels to constrict.
During a moderate heart attack, blood flow to the heart muscle is restricted or cut off entirely, damaging and killing muscle tissue.
Later, as the heart begins to heal and scar tissue forms, the organ's left ventricle, its main pumping chamber, slowly enlarges. This enlargement, called remodeling, reduces the organ's blood-pumping efficiency and can eventually lead to heart failure.
In one study, captopril was given to more than 2,200 patients three to 16 days after they had suffered moderate heart attacks.
Researchers found that the drug reduced the overall death rate by 20 percent, the incidence of heart failure by 37 percent and repeat heart attacks by 25 percent.
"This is a very significant finding, particularly in this group of patients, who have a 25 percent mortality risk without treatment," said Dr. Ian Clements, a Mayo cardiologist who participated in the study.
Dr. Clements said the drug works because it changes the way the heart repairs itself after a heart attack. This stops the enlarging process and enables the organ to maintain its pumping efficiency.
A number of studies involving heart-failure patients and animals hinted that the drugs might be beneficial in treating heart-attack victims, Dr. Clements added, but this is the first study that was directed exclusively at survival after a heart attack.
In another study, enalapril was given to more than 4,200 patients who were suffering from heart failure. Although researchers found only a small reduction in overall mortality rates, they did find that hospitalizations for heart failure dropped 36 percent and deaths caused by progressive heart failure declined by 21 percent.
The captopril study involved 112 hospitals linked to 45 medical centers, including the Mayo Clinic. The enalapril study involved 83 hospitals linked to 23 centers in the United States, Canada and Belgium.