May 3, 2012
Aspirin Vs. Warfarin: Both Effective For Heart Failure Treatment
Less costly aspirin is as effective for heart failure patients with normal heart rhythm as other more expensive drugs, such as warfarin, according to breakthrough research published in today´s New England Journal of Medicine.
Researchers, led by clinical principal investigator Shunichi Homma, MD, of Columbia University Medical Center in New York and statistical principal investigator John L.P. (Seamus) Thompson, PhD, of Columbia University´s Mailman School of Public Health, found that aspirin and warfarin are equally effective in preventing strokes in people with heart failure.
They concluded that aspirin is far safer as well, because fewer patients suffer bleeds, brought on by their blood being thinned so much. The equality in effectiveness is dependent, however, on the fact that patients who suffer from heart failure also have a normal heart rhythm. Otherwise, aspirin may not appear to be an effective choice.
For the study, researchers followed more than 2,300 patients at 168 study sites in 11 countries on three continents. The decade-long ℠Warfarin and Aspirin for Reduced Cardiac Ejection Fraction´ (WARCEF) trial is the largest double-blind comparison of these medications ever conducted.
In the head-to-head comparison, researchers found the combined risk of death, stroke, and cerebral hemorrhage was 7.47 percent per year for those taking warfarin (or Coumadin), and 7.93 percent per year for those on aspirin. The researchers noted that the difference was small enough that there was no real significance between the two.
Patients on warfarin had about half the stroke risk of those taking aspirin. However, warfarin patients had more than twice the risk of major bleeding. The team said the results cancel each other out. However, after four or more years spent following patients, there was evidence that warfarin was more effective in preventing the combined outcome of death, stroke, and cerebral hemorrhage.
Both aspirin and warfarin work to reduce the risk of stroke due to a clot or blockage, both in different ways: warfarin thins the blood while aspirin prevents clotting. Warfarin, however, requires a prescription and regular blood work to monitor clotting levels and adjust dosages.
“Since the overall risks and benefits are similar for aspirin and warfarin, the patient and his or her doctor are free to choose the treatment that best meets their particular medical needs. However, given the convenience and low cost of aspirin, many may go this route,” said Homma.
“Patients and their physicians now have critical information to help select the optimum treatment approach,” added Dr. Walter Koroshetz, deputy director of the National Institute for Neurological Disorders and Stroke, which funded the study. “The key decision will be whether to accept the increased risk of stroke with aspirin, or the increased risk of primarily gastrointestinal hemorrhage with warfarin.”
Warfarin is also difficult to take because it interacts with other medicines and some foods meaning patients need to be monitored regularly.
However, one expert, argues that warfarin is not that dangerous.
“The study shown here demonstrates that warfarin quite markedly reduces the risk of stroke associated with heart failure compared with aspirin, but at a cost of an increase in major hemorrhage,” Dr. Andrew Clark, from the British Society for Heart Failure and the University of Hull, told BBC News. “How to interpret that for individual patients means weighing the risk of stroke against the risk of hemorrhage, but also weighting that by importance.”
“I would regard a gastrointestinal hemorrhage requiring transfusion as being of less importance than a stroke, so would tend in favor of warfarin,” he said. “I would be more inclined to prescribe warfarin that previously, but the evidence is not overwhelming.”
Both warfarin and aspirin have risks and benefits, noted the British Heart Foundation in an interview with The Telegraph. However, this study showed that “neither has an advantage over the other overall in preventing stroke or death in the long term.”
“This finding should give patients reassurance when discussing their medication with their heart failure specialist, and more freedom to choose the treatment which works best for them,” said Ellen Mason, a senior cardiac nurse at the foundation.
The randomized trial was double-blinded so neither patient nor clinician were aware which drug the patient was taking. Patients were instructed to take pills from two bottles, labeled aspirin and warfarin; one was an active medication, and the other was a placebo. All patients took regular blood tests; results for patients on active aspirin were generated using an algorithm designed by Thompson.
“This process gave great confidence that the trial was conducted in an unbiased way,” Thompson noted.
Previous studies established warfarin to be superior to aspirin for preventing stroke in heart failure patients with atrial fibrillation. But the WARCEF study was instrumental in concluding that aspirin was clearly a better a choice for heart failure patients with a normal heart rhythm.
“The trial provides clear evidence that anti-coagulant therapy prevents stroke in patients with heart failure who have severe systolic dysfunction but the rates of stroke are too low to justify the routine clinical use of warfarin in most patients with heart failure, in light of the increase in the risk of bleeding,” wrote John Eikelboom in an accompanying editorial to the study.