Methods: We randomly assigned 614 patients with permanent atrial fibrillation to undergo a lenient rate-control strategy (resting heart rate less than110 beats per minute) or a strict rate-control strategy (resting heart rate less than 80 beats per minute and heart rate during moderate exercise less than 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 less than 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 less than 0.001) with fewer total visits (75 [median, 0], vs. 684 [median, 2]; P less than 0.001). The frequencies of symptoms and adverse events were similar in the two groups.
Conclusions: In patients with permanent atrial fibrillation, lenient rate control is as effective as strict rate control and is easier to achieve.
It was previously known that uncontrolled atrial fibrillation results in tachycardia mediated cardiomyopathy over time. The precise target for preventing this outcome was not known. This study did not report changes in ejection fraction in these patients but there was no difference in events between the two strategies. The average heart rates achieved were fairly similar. So this study does not refute the idea of aggressive rate control for prevention of tachycardia mediated cardiomyopathy.
Commentary from DB’s Med Rants here.