Study: Heart rhythm drug cuts stroke risk by 1/3

The drug, known by the brand name Multaq and chemically as dronedarone, is being developed by French drugmaker Sanofi-Aventis to treat atrial fibrillation, the most common type of irregular heart rhythm and the key risk factor for stroke.

A company-sponsored study called ATHENA, which includes more than 4,600 patients aged 70 or older in 37 countries, showed Multaq lowered risk of both ischemic and hemorrhagic stroke by 34 percent, compared with a dummy pill, in patients with atrial fibrillation. The condition, in which the heart's upper chambers beat irregularly, affects about 2.5 million Americans and can lead to stroke, congestive heart failure and other disabling and deadly complications.

According to the company, the reduced stroke risk began soon after patients started taking Multaq and lasted throughout the 12- to 30-month follow-up in the study.

One of the lead investigators, Professor Stuart Connolly of the cardiology department at Canada's McMaster University, called the study a "landmark" that would bring a major shift in how doctors manage atrial fibrillation.

"It's the first time that an anti-arrhythmic drug has shown a significant impact on cardiovascular outcomes," Connolly said in a statement.

Last May, Sanofi-Aventis reported that, when given on top of standard therapy, Multaq lowered risk of hospitalization from heart complications or death from any cause by one-fourth, compared to patients in a comparison group getting a placebo.

Side effects in the latest trial included gastrointestinal problems and rash and other skin disorders.

Sanofi-Aventis previously sought approval from the U.S. Food and Drug Administration to sell Multaq, but the application was rejected in August 2008. At the time, the company had begun the ATHENA study and said it would reapply in 2008 with the results of ATHENA.