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Studies Suggest Rate Control Equal to Rhythm Control in Some AF Patients
March 23, 2002

ATLANTA, Georgia (ACC) -- Both rate control and rhythm control are reasonable goals in patients with atrial fibrillation (AF), according to two new studies that indicated they are at least equal in efficacy.

Results of the AFFIRM (Atrial Fibrillation Follow-up Investigation in Rhythm Management) and RACE (Rate Control vs. Electrical Cardioversion for Persistent Atrial Fibrillation) trials were discussed by their investigators during a news conference here Monday, March 18, 2002. AFFIRM randomized patients to medical therapy either to restore atrial rhythm or to control ventricular heart rate, whereas RACE compared medical therapy to control heart rate with electrocardioversion of rhythm.

“Rate control is considered by many physicians as a secondary strategy for AF,” said D. George Wyse, MD, PhD, of the Cardiac Arrhythmia Clinic at the University of Calgary in Calgary, Alberta, Canada.

Now, with the AFFIRM trial, continued Dr. Wyse, “We can say that [rate control] is at least as good as rhythm control and should be considered a primary strategy.”

AFFIRM randomized 4,060 elderly patients to medical management of AF. The primary study endpoint, total mortality, was slightly lower in the rate-control arm, although the trend was not quite statistically significant, said Dr. Wyse. At an average of 3.5 years of follow-up, there were 306 deaths in the rate-control arm vs. 356 in the rhythm-control arm.

Outcomes were approximately the same for the two groups in the secondary endpoint, ischemic stroke, he added.

All patients started the trial on anticoagulant therapy, which could be discontinued in the rhythm control arms if patients were thought to be in continuous sinus rhythm. Patients could be crossed over to the alternate trial arm if necessary, although Dr. Wyse noted that the analysis was done on an intent-to-treat basis.

Dr. Wyse said the trial results were pertinent to everyday practice because patients enrolled were older than 65, unless they had other risk factors. AF is prevalent among the elderly, Dr. Wyse said, noting that it is found in 8 percent of people over age 80.

Persistent AF

The difference between primary endpoints in the RACE study was also small.

The rate of death or severe cardiovascular incident was 17.2 percent among the 256 patients in the rate-control trial arm vs. 22.6 percent among the 266 patients in the electrocardioversion rhythm-control arm, said Harry J. Crijns, MD, of the Department of Cardiology at University Hospital Maastricht in Maastricht, the Netherlands.

Cardiovascular mortality rates were 7.0 percent for the rate-control arm and 6.7 percent for the rhythm-control arm; heart failure rates were 3.5 percent and 4.5 percent, respectively; and bleeding complication rates were 4.7 percent and 3.4 percent, respectively.

“Patients with hypertension in particular did not do well with electrocardioversion for rhythm control,” Dr. Crijns said. The rate of mortality, thromboembolism, or other severe complication was approximately 19 percent for rate-control therapy vs. approximately 31 percent for rhythm control. Dr. Crijns speculated that some factor in electroconversion might be especially thrombogenic in hypertensive patients.

“Rate control is not inferior to rhythm control, and it appears to be a very attractive alternative, especially for patients with a high risk of AF recurrence,” Dr. Crijns concluded, adding that it is important to develop safer and more effective antithrombotic drugs.

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