The research, reported May 2 in the New England Journal of Medicine, looked at heart failure patients with a normal heart rhythm.
The results show that the combined rate of death, stroke and brain hemorrhage was not statistically different between the two groups, at 7.47 percent per year for patients taking warfarin and 7.93 percent per year for those taking aspirin.
Heart failure is a condition in which the heart can’t pump enough blood to the body. A weakened heart increases the risk of blood clots that can cause a fatal or disabling stroke. Both aspirin and warfarin reduce the risk of stroke, but they do so by different mechanisms and with different risks.
“For the first time, clinicians have reassurance that they don’t need to put people with heart failure who have a normal rhythm on anticoagulants like warfarin, which increase the risk of bleeding,” says co-author Douglas L. Mann, MD, chief of the cardiovascular division at Washington University School of Medicine in St. Louis, who treats patients at Barnes-Jewish Hospital. “We can give patients aspirin and be reassured that it’s not going to either worsen the heart failure or lead to increased risk of death.”
The decade-long WARCEF trial (Warfarin and Aspirin for Reduced Cardiac Ejection Fraction) followed 2,305 patients and compared the anticoagulant warfarin, known by the brand name Coumadin, to aspirin. Previous studies have shown that warfarin is superior to aspirin for preventing stroke in heart failure patients with atrial fibrillation, a common irregular heart beat. WARCEF is the first study to compare warfarin to aspirin for most heart failure patients – those with a normal heart rhythm.
Patients enrolled in the trial were randomly assigned to one of two groups. One group received aspirin and placebo warfarin. A second group received warfarin and placebo aspirin. Neither the patients nor clinicians knew which active drug a particular patient received until the end of the study. Since patients on warfarin require regular blood tests, all patients’ blood was monitored whether or not they were taking active warfarin.
With at least 6 million Americans living with heart failure, this study answers an important clinical question.
“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,” says principal investigator Shunichi Homma, MD, of Columbia University Medical Center/New York-Presbyterian Hospital. “However, given the convenience and low cost of aspirin, many may go this route.”
Aspirin makes blood cells called platelets less “sticky,” reducing their ability to clump together and form clots. Downstream of this, warfarin interferes with chemical reactions in the body’s so-called “coagulation cascade,” thereby reducing clotting. While warfarin is associated with a greater risk of bleeding, aspirin may inhibit other medications frequently prescribed to heart failure patients. Unlike aspirin, warfarin requires a prescription and patients must have regular blood tests to monitor clotting levels.
While the study found no difference in the combined risk of brain hemorrhage, stroke and death, the two drugs did differ in the risks of individual problems. Specifically, patients taking warfarin had almost half the risk of stroke compared to those taking aspirin. And patients taking warfarin had more than twice the risk of major bleeding. According to the investigators, these results cancel each other out, and point to the importance of tailoring the treatment to individual patients.
“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,” says Walter Koroshetz, MD, deputy director of the National Institute for Neurological Disorders and Stroke, which supported the trial.
However, in patients followed four years or longer, there was evidence that warfarin was more effective overall in preventing deaths, strokes and cerebral hemorrhages.
“As we analyze the data further, we hope to be able to identify whether some patients will clearly benefit from one drug versus the other over time,” Mann says.
Washington University School of Medicine’s 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked sixth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.
Homma S, Thompson JLP, Pullicino PM, Levin B, Freudenberger RS, Teerlink JR, Ammon SE, Graham S, Sacco RL, Mann DL, Mohr JP, Massie BM, Labovitz AJ, Anker SD, Lok DJ, Ponikowski P, Estol CJ, Lip GYH, DiTullio MR, Mejia V, Gabriel AP, del Valle ML, Buchsbaum R, Sanford AR, Moy CS, for the WARCEF Investigators. Warfarin and aspirin in heart failure patients in sinus rhythm. New England Journal of Medicine. Online May 2, 2012.
Funding for the trial was provided by two grants from the National Institute for Neurological Disorders and Stroke (U01-NS-043975, U01-NS-039143) to Homma and Thompson as principal investigators in medicine and biostatistics. Warfarin and warfarin placebo were provided by Taro Pharmaceuticals U.S.A. Inc., Hawthorne, N.Y., and aspirin and aspirin placebo, by Bayer HealthCare LLC, Morristown, N.J. Study findings were first presented at the International Stroke Conference in February.