Sanofi-aventis’ potential blockbuster Multaq (dronedarone) has been shown to reduce the risk of stroke by more than a third in patients with an irregular heartbeat.

The Phase III results from the ATHENA study were presented at the European Society of Cardiology congress in Munich, Germany, and showed the risk of stroke was reduced by 34% in patients with atrial fibrillation or atrial flutter.

This is significant as atrial fibrillation increases the risk of stroke by up to five times and is responsible for 15-20% of all strokes.

“ATHENA is a landmark trial that will lead to a paradigm shift in the management of atrial fibrillation as it is the first time that an anti-arrhythmic drug has shown a significant impact on cardiovascular outcomes,” said Professor Stuart Connolly, co-principal investigator of the study and professor at Canada’s McMaster University.

Previous results from the study found the risk of cardiovascular hospitalisation or death was reduced by 24% when taking the drug with standard therapy.

The ATHENA study is the only double-blind, anti-arrhythmic, morbidity-mortality study in patients with atrial fibrillation. It was conducted in more than 550 sites in 37 countries and enrolled a total of 4,628 patients.

Multaq has been granted priority review by the US Food and Drug Administration and a registration dossier is also under regulatory review by the European Medicines Agency.

In the UK alone, experts have suggested the drug could prevent up to 10,000 strokes a year.