Lenient versus Strict Rate Control in Patients with Atrial Fibrillation

Background Rate control is often the therapy of choice for atrial
fibrillation. Guidelines recommend strict rate control, but this
is not based on clinical evidence. We hypothesized that lenient
rate control is not inferior to strict rate control for
preventing cardiovascular morbidity and mortality in patients with
permanent atrial fibrillation.

Methods We randomly assigned 614
patients with permanent atrial fibrillation to undergo a
lenient rate-control strategy (resting heart rate <110
beats per minute) or a strict rate-control strategy (resting
heart rate <80 beats per minute and heart rate during
moderate exercise <110 beats per minute). The primary
outcome was a composite of death from cardiovascular causes,
hospitalization for heart failure, and stroke, systemic embolism,
bleeding, and life-threatening arrhythmic events. The
duration of follow-up was at least 2 years, with a maximum of
3 years.

Results The estimated cumulative
incidence of the primary outcome at 3 years was 12.9% in the
lenient-control group and 14.9% in the strict-control group,
with an absolute difference with respect to the
lenient-control group of –2.0 percentage points (90%
confidence interval, –7.6 to 3.5; P<0.001 for the
prespecified noninferiority margin). The frequencies of the
components of the primary outcome were similar in the two
groups. More patients in the lenient-control group met the heart-rate
target or targets (304 [97.7%], vs. 203 [67.0%] in the
strict-control group; P<0.001) with fewer total visits (75
[median, 0], vs. 684 [median, 2]; P<0.001). The frequencies of
symptoms and adverse events were similar in the two groups.