Warfarin has been the gold standard for reducing stroke in patients with atrial fibrillation for more than 20 years. Now an international study by McMaster University researchers has found a new medication to be superior to warfarin in the reduction of stroke and bleeding complications, especially bleeding into the brain.

Dabigatran is the first oral blood thinner in more than 50 years that has been found to be safer and more effective than the existing therapy.

The results of the McMaster-led study, which compared dabigatran to warfarin in patients with atrial fibrillation at risk for stroke, were announced this week at the European Society of Cardiology Congress in Barcelona, Spain, and published simultaneously in the online edition of the New England Journal of Medicine.

Stuart Connolly, a professor of medicine in the Michael G. DeGroote School of Medicine and a member of the Population Health Research Institute at McMaster University and Hamilton Health Sciences, was the co-principal investigator of the RE-LY (Randomized Evaluation of Long-term anticoagulant therapY) study, which involved 18,000 patients in 44 countries.

Atrial fibrillation is a common disorder of the heart rhythm that causes the muscles of the atria to quiver instead of beat at regular intervals. The condition affects about one per cent of the population and up to 10 per cent of people over the age of 80.

Warfarin has many shortcomings, including the need for frequent blood monitoring and a significant risk of increased bleeding.

The results of two other McMaster-led studies were also presented at the European Society of Cardiology Congress.

The ACTIVE-I (Atrial Fibrillation Clopidogrel Trial With Irbesartan for Prevention of Vascular Events) study found the hypertension drug irbesartan reduced the risk of heart failure complications and the combination of stroke, blood vessel blockage and transient ischemic events, known as ministrokes, in patients with atrial fibrillation.

The study was presented by Salim Yusuf, director of the Population Health Research Institute and chair of the ACTIVE-I steering committee.

The CURRENT-OASIS 7 (Clopidogrel Optimal Loading Dose Usage to Reduce Recurrent EveNTs/Optimal Antiplatelet Strategy for InterventionS) study found high doses of the blood thinner clopidogrel significantly reduced complications in heart patients undergoing angioplasty to clear blocked arteries.

The researchers found that patients undergoing angioplasty who were given double the standard dose of clopidogrel for about a week had a reduced risk of heart attack and stent thrombosis, the formation of life-threatening blood clots inside stents that prop open narrowed arteries.

The CURRENT-OASIS 7 trial was led by Shamir Mehta, an associate professor of medicine in the Michael G. DeGroote School of Medicine and a member of the Population Health Research Institute.

The ACTIVE-I and CURRENT-OASIS 7 trials were sponsored by Sanofi-Aventis and Bristol-Myers Squibb, and the RE-LY trial was sponsored by Boehringer-Ingelheim. All three studies were conducted independently by the Population Health Research Institute.