Antibiotics don't seem to protect heart. (Biomedicine).

A report made public last month reinforced the idea that antibiotics can protect some people with cardiovascular disease against subsequent heart attacks, possibly by fighting an infection underlying the disease (SN: 3/16/02, p. 164). However, two larger, subsequently released studies--one funded by an antibiotic manufacturer--show weak evidence at best of the purported effect.

In one study, Michael Dunne of the pharmaceutical firm Pfizer and his colleagues gave either the antibiotic azithromycin or a placebo pill to some 7,700 people who had both a history of heart disease and evidence of infection with Chlamydia pneumoniae. Some past studies have associated that bacterium with heart disease. The volunteers took pills weekly for 3 months and were monitored for an average of 2 years.

The researchers observed no significant long-term difference in heart health between the two groups. Nevertheless, the new data suggest that drug recipients might be less likely to suffer heart events, including heart attacks, during the 6 months after treatment begins.

Another team of researchers, led by Bojan Cercek of Cedars-Sinai Medical Center in Los Angeles, gave a daily dose of either azithromycin or a placebo to 1,440 patients for 5 days. The drug had no long-term benefit.

Both teams presented their findings on March 19 at a meeting of the American College of Cardiology in Atlanta.

The two studies undermine the earlier study and other evidence that antibiotics can reduce heart disease, says Mark J. Eisenberg of the Jewish General Hospital in Montreal. "If there is any benefit, it's pretty minor," he says.

Joseph Brent Muhlestein of LDS Hospital in Salt Lake City says that although the new findings don't demonstrate an effect of the antibiotics on the incidence of heart disease, the possibility that infection-fighting drugs could help some patients with heart disease still merits study. --B.H.