Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM)

BACKGROUND:

Atrial fibrillation is an extremely common and increasingly prevalent cardiac arrhythmia, particularly in the elderly, and is an important risk factor for stroke. Management of atrial fibrillation remains controversial, and although antiarrhythmic drugs are widely used for this condition, clinical studies to support their use are meager. Management of atrial fibrillation has at least three components: restoration and maintenance of sinus rhythm; heart rate control when maintenance of sinus rhythm or when cardioversion is not attempted or impossible; and anticoagulation. The first component of management uses antiarrhythmic drugs and the second uses a different group of antiarrhythmic drugs and catheter ablation. The third is anticoagulant therapy for patients in whom normal sinus rhythm cannot be maintained or in whom cardioversion is not attempted.

The initiative was developed by staff of the Clinical Trials Branch and the NHLBI Working Group on Atrial Fibrillation which met in Bethesda in April, 1993. The initiative was given concept clearance by the February 1994 National Heart, Lung, and Blood Advisory Council. The Request for Proposals was released in May 1994.

DESIGN NARRATIVE:

A randomized multicenter trial. The trial enrolled only patients with atrial fibrillation who were at high risk for stroke, that is, over 65 years of age or less than 65 and with one or more other risk factors for stroke such as systemic hypertension, diabetes mellitus, congestive heart failure, transient ischemic attack, prior cerebral vascular accident. High risk patients were treated with the anticoagulant warfarin. Cardioversion (electrical or pharmacologic) might have been attempted before randomization, but if it was unsuccessful, the patient was excluded from further consideration for randomization. Normal sinus rhythm must have persisted for one hour or greater after cardioversion to qualify as successful cardioversion. Patients were randomly assigned to treatment groups which included maintenance of sinus rhythm or heart rate control. Both treatment groups had two steps.