Background: Rate control is the cornerstone of atrial fibrillation management, but the optimal target heart rate is unknown. Guidelines recommend strict rate control, but whether this approach actually improves patient outcomes has not been proven. Van Gelder and colleagues studied lenient rate control to determine if it is as effective as strict rate control in preventing cardiovascular morbidity and mortality in persons with atrial fibrillation.

The Study: The authors evaluated data from the Rate Control Efficacy in Permanent Atrial Fibrillation: a Comparison between Lenient versus Strict Rate Control II study, a prospective randomized trial examining whether lenient rate control (less than 110 beats per minute [bpm] at rest) was noninferior to strict rate control (less than 80 bpm at rest and less than 110 bpm with moderate exercise) in preventing cardiovascular events over two to three years. Eligible patients were younger than 80 years, had permanent atrial fibrillation for up to 12 months, were receiving anticoagulant therapy, and had a mean resting heart rate greater than 80 bpm. A total of 614 patients were given one or more rate-controlling drugs (i.e., beta blockers, nondihydropyridine calcium channel blockers, and digoxin) to achieve their target heart rate. The primary outcome was a composite of cardiovascular-associated outcomes, including death, embolism, sustained ventricular tachycardia, syncope, hospitalization for heart failure, and implantation of a cardioverter-defibrillator.

Results: Significantly more patients were able to achieve their target heart rates in the lenient rate-control group compared with the strict rate-control group (97.7 versus 75.2 percent, respectively), and significantly fewer followup visits were needed in the lenient rate-control group to achieve the target heart rate. No difference was noted between the groups regarding the primary outcome. There was also no difference between the groups with regard to all-cause mortality, heart failure stage, hospitalization rate, or adverse events, although the lenient ratecontrol group had a lower risk of stroke (hazard ratio = 0.35). There was no difference between the groups in the prevalence of atrial fibrillation symptoms, including palpitations, dyspnea, or fatigue.

Conclusion: The authors conclude that lenient rate control is easier to achieve than strict rate control in patients with permanent atrial fibrillation, with a similar rate of major clinical events.