Antibiotics Cut Heart Attack Risk

Killing off a pneumonia-causing bacterium in infected cardiac patients reduced the risk of a second heart attack, cardiologists have found. The provocative results from a pilot trial, described in the latest issue of the journal Circulation, suggest that antibiotics could become a cheap treatment for some types of heart disease.

In the past year, researchers have detected a bacterium called Chlamydia pneumoniae--a relative of the bug that causes the venereal disease chlamydia--in the arterial blockages of 75% of patients with atherosclerosis, or partially clogged arteries. Sandeep Gupta and his colleagues at the St. George's Hospital Medical School in London reasoned that if the organism were somehow causing blood clots, then killing C. pneumoniae with antibiotics might cut a patient's heart attack risk.

Gupta's team measured the blood levels of antibodies to C. pneumoniae in 213 male patients who had previously suffered a heart attack. Eighty patients had high antibody levels, presumably indicating a more serious chlamydia infection. The researchers treated half these patients for 3 days with azithromycin, an antibiotic that wipes out chlamydia infection. Eighteen months later, only 8% of the treated men had suffered another heart attack or other serious cardiac event, or had died; in contrast, 28% of those who were untreated or given placebos suffered such consequences. Among the 59 men who initially had no chlamydia antibodies, the rate was 7%.

"The results are provocative," says Elizabeth Hammond, a University of Utah pathologist who also studies chlamydia's role in heart disease. But she says a larger study is needed to prove the benefit of treatment and to determine whether it also helps patients who haven't already had a heart attack. "To really know that this is true, we need a randomized, controlled trial," Hammond says. Gupta and his colleagues in London are already recruiting patients in England for such a study.

If azithromycin does pan out as a treatment for heart disease, it could be particularly beneficial in developing countries such as India, Gupta says. There, heart disease rates are climbing swiftly, but few people can afford expensive treatments such as bypass surgery and balloon angioplasty. But antibiotics might not help all heart disease patients, says Gupta. And avoiding the big risk factors--smoking, lack of exercise, and improper diet--will still be the most effective prevention. "These remain the paramount factors," he says.