Doctors may be writing fewer prescriptions for the blood-thinning drug warfarin in the wake of a major new international study that found that an ordinary 325 mg aspirin is just as effective in treating a common form of heart failure, the study's lead author predicts.
"Overall, aspirin is just as good as warfarin," says Shunichi Homma, M.D., associate chief of cardiology at New York Presbyterian Hospital/Columbia University Medical Center. Homma led the study published in the May 17 issue of the New England Journal of Medicine.
For the 4 million or so U.S. patients who have heart failure (cardiomyopathy) with a normal heart rhythm, aspirin is easier to take than warfarin, which requires frequent testing and can cause serious gastrointestinal bleeding, says Homma. In such patients, the weakened cardiac muscle can't pump all of the blood from the heart's chambers; blood-thinning medications help prevent strokes by keeping the stagnant blood from coagulating and causing a clot that could travel to the brain.
The new study followed 2,305 patients at 168 study sites in 11 countries for an average of 3 1/2 years. Neither the patients nor their doctors knew which of the two daily pills prescribed as warfarin and aspirin were real or a dummy, Homma says. The patients, whose average age was 61 — young for heart failure — were quite ill, he says. Most were also on ACE inhibitors and beta blockers, prescribed, typically, to lower blood pressure.
The study found the number of strokes, hemorrhages or deaths that occurred in each group was virtually the same. The warfarin group had 7.47 of these events per 100 patient-years, compared with 7.93 for the group that took an ordinary aspirin pill daily, a difference that was not statistically significant. Warfarin proved to be the better blood-thinning agent, reducing the number of ischemic strokes relative to aspirin, but the benefit was offset by more cases of major bleeding, the study found.
Stuart Connolly, M.D., director of cardiology at McMaster University in Hamilton, Ontario, who cowrote an editorial that accompanied Homma's article in the journal, hailed the research for answering important questions. Among other things, it showed that while warfarin greatly lowers the risk of an ischemic stroke, that's not a significant benefit to this type of heart failure patient, whose risk isn't very high to begin with.
"Warfarin has enough problems that it's just not going to get used in this population," just to protect against the tiny chance of stroke, he says.
However, Homma cautions that for the 30 percent of heart failure patients who have an abnormal heart rhythm, warfarin — also known by the brand-name Coumadin — remains a proven treatment.
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