March 31 (HealthDay News) -- Combining the clot-preventing drug Plavix with aspirin is an effective substitute treatment for people at high risk of stroke and heart attack because of the abnormal heart rhythm called atrial fibrillation but who cannot take the recommended therapy, a new study shows.
Standard treatment for atrial fibrillation, in which substandard heart action can lead to the formation of artery-blocking clots, is the anticoagulant warfarin (Coumadin). But at least 40 percent of the more than 2 million Americans with atrial fibrillation do not take the drug, Dr. Stuart Connolly, director of cardiology at McMaster University in Canada, said at the annual scientific session of the American College of Cardiology, in Orlando, Fla.
Some are vulnerable to the increased risk of bleeding caused by Coumadin, but many just can't stand the dietary restrictions and frequent blood tests required of users. Until now, the only alternative therapy has been aspirin, which has a clot-preventing effect.
Connolly led a trial that tested the combination of Plavix (clopidogrel) and aspirin. It involved 7,554 people with atrial fibrillation and at least one risk factor for stroke. All took aspirin daily, and half also took 75 milligrams a day of Plavix.
Among those who took the combination, "the incidence of major vascular events was reduced by 11 percent, which was a highly significant result," Connolly said.
The main effect of the combination was to reduce the incidence of stroke by about a third, from 3.4 percent to 2.4 percent a year, Connolly said. The incidence of heart attacks was reduced from 0.9 percent a year to 0.7 percent a year, a result that was not statistically significant, he said.
The incidence of major bleeding, such as hemorrhaging, was higher among those taking the combination -- 2 percent a year compared with 1.27 percent among those taking aspirin alone.
"When we consider the risk for patients, combination therapy prevents 28 strokes, 17 of them disabling, and six myocardial infarctions [heart attacks] per 1,000 patients a year, at a cost of 20 major bleeds, three of which would be fatal," Connolly said.
The bottom line, he said, is that "we can reduce major vascular events, primarily strokes, with a bearable cost in bleeding."
Because of the trial results, "I personally as a clinician would prescribe clopidogrel and aspirin for patients who could not take warfarin but who appeared to be at limited bleeding risk or risk of falling," said Dr. Aaron D. Kugelmass, chief of cardiology at the Baystate Medical Center in Springfield, Mass., and program chairman of the meeting.
The risk of falling must be considered, he said, because a fall can cause bleeding in the brain.
The combination therapy would be advisable for "upwards of 40 or 50 percent" of people with atrial fibrillation who now do not take Coumadin, Kugelmass said.
But he said he would not recommend the combination for people advised to take Coumadin for other reasons, such as having an artificial heart valve.
"This trial was for a very specific indication -- for patients with atrial fibrillation who can't take Coumadin," Kugelmass said. "I would not stop others who are on Coumadin to put them on this."
A report on the trial was published online March 31 in the New England Journal of Medicine.
SOURCES: Stuart Connolly, M.D., director, cardiology, McMaster University, Hamilton, Ontario, Canada; Aaron D. Kugelmass, M.D., chief, cardiology, Baystate Medical Center, Springfield, Mass.; March 31, 2009, New England Journal of Medicine, online