Part of largest randomised international trial program ever conducted in atrial fibrillation (AF) discontinued

Study treatments for the ACTIVE W trial of the ACTIVE (Atrial Fibrillation Clopidogrel Trial with Irbesartan for Prevention of Vascular Events) program have been discontinued due to a significant difference in efficacy, in favour of the standard oral anticoagulation (OAC) over antiplatelet therapy (clopidogrel plus aspirin).

The ACTIVE trial, the largest randomised international trial program ever conducted in atrial fibrillation (AF), was designed to respond to a largely unmet medical need in the treatment of patients with AF, who are at an increased risk of life-threatening vascular events such as stroke, myocardial infarction and death.

Investigators at 600 sites will adjust their patients' medications and continue to monitor their health. Approximately 3,000 patients worldwide will be affected by the changes in the study.

After an interim analysis of the study, the recommendation of an independent Data Safety Monitoring Board to discontinue the ACTIVE W trial was endorsed by the ACTIVE study steering committee.

The board also recommended two other trials of the ACTIVE program be continued. The study's steering committee agreed with the recommendation to discontinue study treatments for ACTIVE W, and endorsed the recommendation to continue the ACTIVE A (clopidogrel compared with ASA alone), and ACTIVE I (irbesartan to placebo in addition to usual blood pressure lowering therapy).

"In the ACTIVE W trial, most of the patients had been receiving OAC prior to entry into the trial," said SalimYusuf, PhD, chairman of the steering committee for the ACTIVE trial program. "These patients achieved high levels of compliance to OAC in the recommended therapeutic range. In the ACTIVE-W trial, a clear benefit in favour of OAC was evident."

Stuart Connolly, MD, principal investigator of the program, emphasized that: "It is important to continue the ACTIVE A and ACTIVE I parts of the study program to evaluate the potential role which clopidogrel can play in the management of atrial fibrillation patients who are intolerant to oral anticoagulants, and to understand the role of irbesartan in patients with atrial fibrillation."

Clinical guidelines recommend the use of OAC therapy for most patients with atrial fibrillation in order to prevent embolic events. However, OAC therapy is associated with a narrow therapeutic window, requires regular monitoring and is contraindicated in some patients. Aspirin is an option in patients who cannot tolerate OACs. The ACTIVE trial programme is designed to evaluate the appropriate place of clopidogrel plus aspirin in the prevention of embolic events in atrial fibrillation patients.

ACTIVE is a phase III multicenter, multinational clinical development program that includes three trials. In ACTIVE A, clopidogrel plus aspirin is compared with aspirin alone in patients who have a contraindication for OACs or are unwilling to take an OAC, with the hypothesis that clopidogrel plus aspirin would be superior to aspirin. ACTIVE I is evaluating whether the angiotensin II receptor antagonist, irbesartan, is superior to placebo (in addition to usual blood pressure lowering therapy) in preventing vascular events in patients with atrial fibrillation.

The ACTIVE trial program is being conducted at more than 600 sites worldwide in 30 countries.

Atrial fibrillation is the most common chronic cardiac rhythm disturbance and it is responsible for a substantial amount of morbidity, disability and mortality in the general population.