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Word of the Day

Lenient = strict rate control in prevention of adverse outcomes in AF

Clinical Question:
Is lenient rate control as effective as strict rate control for preventing adverse outcomes in patients with permanent atrial fibrillation?

Bottom Line:
In patients with permanent atrial fibrillation (AF), lenient rate control with a target heart rate (HR) of less than 110 beats per minute (bpm) is as effective as strict rate control in reducing adverse outcomes without increasing symptoms or number of hospitalizations. In addition, a lenient target heart rate goal can be achieved with fewer medications and fewer clinic visits. (LOE = 1b)

Van Gelder IC, Groenveld HF, Crijns HJ, et al. Lenient versus strict rate control in patients with atrial fibrillation. N Engl J Med 2010;362(15):1363-1373.  [PMID:20231232]

Study Design:
Randomized controlled trial (nonblinded)

Industry + govt


Outpatient (specialty)

Based on empirical data only, current American College of Cardiology/American Heart Association guidelines recommend strict rate control for patients with AF with a target HR of 60 to 80 bpm at rest and 90 to 115 bpm with exercise. In this open-label noninferiority study, investigators recruited patients 80 years and younger with permanent AF for less than 1 year. All patients had a resting HR greater than 80 bpm, were receiving oral anticoagulation or aspirin, and were able to exercise. Those with pacemakers or defibrillators, unstable heart failure, or history of stroke were excluded. Using concealed allocation, 311 patients were randomized to the lenient rate control strategy (target HR < 110 bpm at rest) and 303 were randomized to the strict rate control strategy (target HR < 80 bpm at rest and < 110 bpm with moderate exercise). The groups were well matched though patients in the lenient control group had a higher prevalence of coronary artery disease. During a dose-adjustment phase, patients in both groups were followed up every 2 weeks and received one or more rate-controlling drugs (ie, beta-blockers, nondihydropyridine calcium-channel blockers, and digoxin) to achieve the target HR. At the end of this phase, almost all patients in the lenient control group had achieved the target HR as compared with only two thirds of patients in the strict control group. Overall, this required 75 follow-up visits in the lenient group and 684 visits in the strict group (P <.001). Analysis was by intention to treat. At the end of the dose-adjustment phase, the mean resting HR in the lenient control group was 93 bpm as compared with 76 bpm in the strict control group (P <.001) Although still statistically significant, this difference was less remarkable at the end of the 3-year follow-up period (85 bpm in lenient group vs 76 bpm in strict group; P < .001). The primary outcome was the composite of death from cardiovascular causes, hospitalization for heart failure, stroke, systemic embolism, bleeding, and life-threatening arrhythmic events. At 3 years, the cumulative incidence of the primary outcome between the 2 groups did not differ significantly (12.9% in the lenient group, 14.9% in the strict group). The frequency of symptoms associated with AF and the frequency of hospitalizations were also similar in the 2 groups.


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