MONDAY, March 11, 2002 (HealthDayNews) -- A long course of antibiotics seems to significantly cut the risk of heart attacks and other cardiovascular problems in people with coronary artery disease.
A new study by Finnish scientists has found that people who suffered heart attacks and chest pain who received a three-month course of the drug, clarithromycin, were about 40 percent less likely to suffer more heart and vessel trouble than those who didn't get the drug.
Experts, including the researchers themselves, caution the study was small and the results were far from definitive. However, the findings, which appear in tomorrow's issue of Circulation, do agree with earlier work showing antibiotics seem to protect the heart.
Why that's the case is not entirely clear. Some evidence indicates that Chlamydia pneumoniae, a common respiratory bug, may play a role in the formation or loosening of plaques that damage arteries and trigger heart attacks and strokes.
These germs, which cause 10 percent to 15 percent of all pneumonia cases, are found in about 60 percent of patients with artery plaques.
Drugs called macrolides that help control the bugs -- though not necessarily eradicate them -- may stabilize plaques and reduce the risk of blockages that can starve the heart of blood. Macrolides may also have anti-inflammatory effects, offering a second layer of protection against the progression of vessel disease.
In the latest study, Dr. Juha Sinisalo of Helsinki University and his colleagues followed 148 Finnish men and women, aged 18 to 80, who were treated for heart attacks or severe chest pain between September 1998 and December 2000.
For 85 days, half were given 500 milligrams a day of clarithromycin -- a macrolide sold as Biaxin by Chicago-based Abbott Laboratories, which helped support the study. The rest were given the same amount of dummy tablets.
Over the next three months, 11 patients who received the antibiotics suffered heart attacks, unstable chest pain called angina or died, compared with 19 in the placebo group. Because of the small size of the study, that difference wasn't statistically significant.
Yet, over an average of 1.5 years of follow-up, those who got antibiotics were about half as likely to suffer another heart-related complication, the researchers found. "No signs of this effect diminishing were observed during follow-up," the researchers write.
The study's small size puts its conclusions on statistically shaky ground. However, Christoph R. Meier, a Swiss researcher who has studied the effects of antibiotics on cardiovascular disease, says the results make sense.
"There seems to be some benefit from macrolide treatment in subjects with coronary syndrome and/or post [heart attack]," Meier says. "Whether this is due to antibacterial effects of this drug or not remains controversial. There is a possibility that this has nothing to do with bacterial eradication, but much more with anti-inflammatory effects of certain antibiotics."
Dr. Joseph Brent Muhlestein, a Salt Lake City cardiologist who has studied the link between bacteria and vessel plaques, calls the Finnish work "promising." However, he cautions against prescribing antibiotics to heart patients before larger trials have been done. The results of two such studies are expected soon.
"Until one of these big trials proves it, there's not enough data to make clinical decisions on," he says.
What To Do
For more on heart disease, try the Centers for Disease Control and Prevention or the American Heart Association.