The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial compared rhythm control versus rate control, and use of anticoagulation was recommended in both arms (6). More than 4000 patients who were at least 65 years of age or who had at least 1 risk factor for stroke or death, such as hypertension, diabetes, previous stroke, or poor ventricular function, were followed for a mean of 3.5 years. Slightly more than one third of the patients were enrolled after their first episode of atrial fibrillation, and more than 90% had had their qualifying episode within the previous 6 weeks. In more than two thirds of patients, the qualifying episode lasted at least 2 days. The average patient age was 70 years. Sixty-one percent of patients were men, and 89% were white. Seventy-one percent of patients had hypertension, 38% had coronary heart disease, 18% had previously had failure of antiarrhythmic therapy, and 12% had no apparent heart disease (lone atrial fibrillation). Patients were randomly assigned to rate or rhythm control, and their physicians chose the specific therapies (pharmacologic first, then nonpharmacologic if needed). Anticoagulation was continued indefinitely in the rate-control group and was encouraged in the rhythm-control group but could be stopped at the physician's discretion if sinus rhythm had been maintained for at least 4, and preferably 12, consecutive weeks with antiarrhythmic therapy. The prevalence of sinus rhythm in the rhythm-control group was 82%, 73%, and 63% at 1, 3, and 5 years, respectively. The prevalence of sinus rhythm in the rate-control group was 34.6% at 5 years.