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New Drug May Revolutionize Treatment of Atrial Fibrillation

Reported October 26, 2011


(Ivanhoe Newswire) Atrial fibrillation (AF) is the most common type of heart arrhythmia that causes five times greater risk for stroke. A new drug has the potential to revolutionize the treatment of AF and battle the deadly disorder.

"The majority of patients with atrial fibrillation need an anticoagulant. The current anticoagulant can be a burden for physicians and patients due to its side effects and narrow therapeutic range," Dr. Justin Ezekowitz, from the University of Alberta, was quoted as saying. It is associated with a risk of bleeding and needs very close monitoring, whereas this new drug is taken twice a day and does not require monitoring. Our trial also shows it is not just equivalent, but better than warfarin for preventing strokes. These are important advantages."

The common treatment for AF has been warfarin, an anticoagulant which has been highly effective in preventing stroke in patients with AF. However, it requires patients to come in to their doctor's office for frequent blood tests, is associated with bleeding, and it also can interact with a variety of foods and drugs that patients might also be taking. Apixaban, a new type of oral anticoagulant known as a factor Xa inhibitor, resulted in fewer strokes (ischemic or hemorrhagic) and fewer systemic embolisms, caused less bleeding and resulted in fewer deaths in patients with atrial fibrillation, said Dr. Ezekowitz.

"We have a drug that can increase reductions in death and stroke and it is safer in terms of bleeding," explained Dr. Ezekowitz. "It is also easier to use."

The ARISTOTLE trial randomized 18,201 patients with at least one additional risk factor for stroke. Their mean age was 70 years. There were 19 percent with prior stroke, 87 percent had high blood pressure, 28 percent had heart failure or reduced left ventricular ejection fraction, and 24 percent had diabetesmellitus.

The patients were randomized to apixaban 5 mg twice daily versus dose-adjusted warfarin which is often used to treat AF - using a double-blind, double-dummy design. Warfarin or warfarin placebo was monitored adjusted to a target INR of two to three using a blinded, encrypted point-of-care device. "This was the best possible clinical trial design," says Dr. Ezekowitz.

A bit more than half of the patients (57 percent) had used warfarin before entering the study, and 43 percent were new to warfarin. The patients were followed for 1.8 years, on average.
The study found that apixaban is effective at treating AF. It was also better at reducing all-cause mortality and was associated with less bleeding.

Specifically, apixaban reduced the chance of stroke and systemic embolism by 21 percent, reduced major bleeding by 31 per cent, and reduced mortality, or all cause death, by 11 percent.

Atrial fibrillation is becoming more common due to the aging of the population around the world.
It is also being seen in younger people due to lifestyle factors, especially stress. Also, it is increasing as cardiologists have become better at diagnosing the condition.

SOURCE: Canadian Cardiovascular Congress 2011 held in Vancouver, Canada on October 24, 2011