ACC: Lenient rate control for a-fib is noninferior to strict controlchange the guidelines?
ATLANTA—Contrary to current guidelines, taking a lenient approach to controlling heart rate in patients with atrial fibrillation appears to be just as good as taking a strict approach and poses no greater risk of death or other serious complications, according to the RACE II trial presented today during the late breaking clinical trials session at the American College of Cardiology’s (ACC) 59th annual conference.

The RACE II (Rate Control Efficacy in Permanent Atrial Fibrillation) trial evaluated whether therapy aimed at achieving a resting heart rate of less than 110 beats per minute in patients with atrial fibrillation was “noninferior” to therapy targeted at a resting heart rate of less than 80 beats per minute.

The first randomized trial to investigate the best level of heart rate control in patients with atrial fibrillation, RACE II found that clinical outcomes were similar with the two approaches, but “lenient control was easier and less time consuming,” according to lead author Isabelle C. Van Gelder, MD, a cardiology professor at the University Medical Center Groningen, University of Groningen in Groningen, the Netherlands.

The researchers recruited 614 patients with recent permanent atrial fibrillation with high and low risk. They randomly assigned the patients to lenient rate control, defined as a heart rate of less than 110 bpm at rest, or to strict rate control, defined as a heart rate of less than 80 bpm at rest and less than 110 bpm during moderate exercise. To achieve the target heart rate, patients were treated with beta blockers, calcium-channel blockers, and/or digoxin.

During a follow up that ranged from two to three years, the researchers reported 38 patients in the lenient-control group and 43 patients in the strict-control group either died of cardiovascular causes, were hospitalized for heart failure, or experienced a stroke, a blood clot, serious bleeding or a life-threatening arrhythmia. The estimated cumulative incidence of these events at 3 years was 12.9 percent in the lenient-control group and 14.9 percent in the strict-control group.

Van Gelder reported his similarity was highly statistically significant for the “noninferiority” of the lenient-control strategy. Efforts to achieve the target heart rate were more successful with lenient control than with strict control (98 vs. 67 percent) and required fewer visits to the doctor (75 vs. 684). According to Van Gelder, symptoms were comparable in the two groups.

“Lenient rate control is more convenient since fewer outpatient visits and exams are needed,” said Van Gelder, adding that more than two-thirds of the strict control arm patients needed multiple medications.

“Guidelines, though not evidence-based, recommend strict rate control in patients with atrial fibrillation to reduce symptoms and the risk of heart failure, bleeding and stroke, and to improve quality of life, exercise tolerance and survival,” said Van Gelder. “Our study suggests that lenient rate control is the first-choice strategy in patients with permanent atrial fibrillation.”

Based on their findings, the researchers recommended that lenient rate control may be adopted as first choice rate control strategy in patients with permanent atrial fibrillation, adding that this applies for high and low-risk patients.

“We should treat the patient, not the heart rate,” Van Gelder said in her closing remarks.

Ralph G. Brindis, MD, from Kaiser Permanente and ACC’s incoming president, said that he completely agrees with the concept of the trial, and is especially curious about future quality of life data with RACE II, which is currently ongoing.

RACE II was simultaneously published in the New England Journal of Medicine today.

In the accompanying editorial, Paul Dorian, MD, from the division of cardiology at St. Michael's Hospital in Toronto, wrote about how this trial could affect clinical practice, noting that “a heart-rate target of less than 110 beats per minute at rest, although it may make physicians feel uncomfortable, is probably as useful as the current guideline-recommended target heart rates at rest and during exercise, at least in the medium term.”

He added that “many patients will continue to be symptomatic under the rate-control approach, whether a strict or more lenient target heart rate is used. The RACE II study does not suggest that ventricular rate control is not needed, only that the conventional therapeutic target needs to be reassessed.”