Warfarin and Aspirin Similarly Effective in Heart Failure Treatment

A new study that compared the two most dominant anticlotting medications has found that warfarin was similar to aspirin in preventing deaths and strokes in patients with normal heart rhythm suffering from heart failure (HF).

Researchers at Columbia University (New York, NY, USA), Montreal General Hospital (Canada) and 62 other institutions participating in the 11-country Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction (WARCEF) trial followed 2,305 HF patients (average age 61) with normal heart rhythm and a left ventricular ejection fraction (LVEF) lower than 35%. The researchers randomly assigned patients to receive either 325 mg/day of aspirin or warfarin doses calibrated to a prespecified level of blood thinning. To avoid bias, all patients had blood drawn on the same schedule and their medication adjusted so that neither the patients nor their treating physicians knew which regimen they were taking.

The results showed that during the six-year follow-up period, 13% of the patients experienced a stroke or transient ischemic attack (TIA) and were at heightened risk of recurrence. Death, ischemic stroke, or intracerebral hemorrhage--which combined were the study's primary endpoint--occurred at a rate of 7.47% for patients assigned to warfarin, and 7.93% for patients assigned to aspirin; the difference was not statistically significant. The rates of stroke were low, with annual rates of 0.72% in patients assigned to warfarin and 1.36% for those on aspirin. Each year, major bleeding occurred in 1.8% of patients on warfarin and 0.9% of those on aspirin; intracerebral hemorrhage, however, occurred in 0.12% per year in the warfarin group and only 0.05% percent per year in the aspirin group. The study was presented at the American Stroke Association (ASA) International Stroke Conference, held during February 2012 in New Orleans (LA, USA).

“Although there was a warfarin benefit for patients treated for four or more years, overall, warfarin and aspirin were similar,” said lead author and study presenter Shunichi Homma, MD, of Columbia University. “Given that there is no overall difference between the two treatments and that possible benefit of warfarin does not start until after 4 years of treatment, there is no compelling reason to use warfarin, especially considering the bleeding risk.”

Warfarin decreases blood coagulation by inhibiting vitamin K epoxide reductase, an enzyme that recycles oxidized vitamin K to its reduced form after it has participated in the carboxylation of several blood coagulation proteins, mainly prothrombin and factor VII. It was initially introduced in 1948 as a pesticide against rats and mice and it is still popular for this purpose. In the early 1950s warfarin was found to be effective and relatively safe for preventing thrombosis and embolism in many disorders. It is the most widely prescribed oral anticoagulant drug in North America.

Related Links:
Columbia University
Montreal General Hospital