A study presented at ACC 2010 has shown that lighter control of heart rate can be as effective as strict control and there is no greater risk of death or other serious complications with a more lenient approach.
The rate control efficacy in permanent atrial fibrillation (RACE II) study evaluated whether therapy aimed at achieving a resting heart rate of less than 110 beats per minute in patients with atrial fibrillation (AF) was “noninferior” to therapy targeted at a resting heart rate of less than 80 beats per minute. RACE II, the first randomised trial to investigate the best level of heart rate control in patients with atrial fibrillation, found that clinical outcomes were similar with the two approaches, but lenient control was easier and less time-consuming to achieve.
“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 Isabelle C. Van Gelder, cardiology professor, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands, and the Interuniversity Cardiology Institute Netherlands, Utrecht, The Netherlands.
“Our study suggests that lenient rate control is the first-choice strategy in patients with permanent AF.”
Previous studies have shown that patients fare just as well when medications are used to control the heart rate, rather than trying to force the heart back into a normal rhythm. But whether maintaining a near-normal heart rate (strict rate control) is necessary to keep patients healthy over the long run has been unknown.
The researchers recruited 614 patients with AF, randomly assigning them 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, 38 patients in the lenient-control group and 43 patients in the strict-control group either died of cardiovascular causes, were hospitalised 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% in the strict-control group. This 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%) and required fewer visits to the doctor (75 vs. 684, with a median of 0 and 2 visits, respectively).Symptoms were comparable in the two groups.