Antibiotics may help heart attack victims live longer, as well as lower the risk of future heart attacks, according to a new study.

"Patients with acute heart attacks or severe angina seem to benefit from treatment with a macrolide antibiotic," says lead author Juha Sinisalo, M.D., of Helsinki University Central Hospital in Helsinki, Finland, "The most likely mechanism of action is [the antibiotic] clarithromycin's antibacterial effect."

Inflammation within the blood vessels plays a key role in the development of coronary heart disease.

What does killing bacteria have to do with preventing heart attacks? In recent years, researchers have become increasingly aware that inflammation within the blood vessels — possibly as part of an immune system reaction to real or perceived infection — plays a key role in the development of coronary heart disease. Evidence from animal and human studies indicates that Chlamydia pneumoniae and other infections are more commonly found in coronary heart disease sufferers.

Based on this study, should people at risk for heart attack call their doctor and demand antibiotics? Certainly not, says TheDoctor's Richard Smalling, M.D., Ph.D., J. Brent Sterling Professor of Cardiovascular Medicine at UT Medical School in Houston.

"This is the kind of study," Dr. Smalling says, "that gives researchers new insight into why some people develop cholesterol deposits in their arteries and others do not. It may also point to potential new therapies to prevent this process. But the fairly small positive effect found in this study must be balanced against the greater risks of widespread adminstration of antibiotics. Unfortunately, the more widely an antibiotic is used, the more likely it is that the targeted bacteria will develop a resistance to the antiobiotic. Today, overuse of antibiotics is leading to a very dangerous situation in which doctors encounter more and more infections caused by strains of bacteria which they cannot fight. As for this study, we will have to wait and see if the results are duplicated in larger trials before we can begin to consider adopting antibiotics as a treatment for heart disease."

As reported in the March 12 issue of Circulation: Journal of the American Heart Association, Dr. Sinisalo and his colleagues studied 148 patients with acute coronary problems who were admitted to one of nine different hospitals in Finland. 74 got a macrolide antibiotic for 85 days; the others got a placebo. Neither the patients nor the researchers knew who was receiving the drug or the placebo.

At the end of the study, 16 of the clarithromycin patients and 27 of the placebo patients had died, or suffered a nonfatal heart attack, unstable angina or a stroke. That difference was statistically significant. "The action of clarithromycin seems to be long-lasting," says Sinisalo, who nevertheless conceded that "this study must be interpreted with caution because of the small number of patients."

Reviewed by: Richard W. Smalling, M.D., Ph.D.