Effect of Lenient Versus Strict Rate Control on Cardiac Remodeling in Patients With Atrial Fibrillation: Data of the RACE II (Rate Control Efficacy in Permanent Atrial Fibrillation II) Study

Study Questions:

Is lenient rate control associated with more adverse cardiac remodeling than strict rate control in patients with atrial fibrillation (AF)?


Patients (mean age 68 years) with persistent AF were randomly assigned to lenient rate control (resting rate <110 bpm, n = 261) or strict rate control (resting rate <80 bpm, rate during moderate exercise <110 bpm, n = 256). Rate control was achieved with beta-blockers, calcium-channel blockers, and/or digoxin. Echocardiograms were performed at baseline and at a median of 3 years of follow-up. The primary endpoint was change in left atrial diameter (LAD), left atrial volume (LAV), and left ventricular end-diastolic diameter (LVEDD).


The mean resting rate was significantly higher in the lenient group (93 bpm) than in the strict group (76 mm). The mean baseline LAD (46 mm), LAV (approximately 72 ml), and LVEDD (51 ml) did not differ significantly between the lenient and strict rate control groups. There was no significant change in these parameters in either group during follow-up. The only independent predictor of increases in LAD, LAV, and LVEDD was female gender.


Lenient rate control does not promote adverse cardiac remodeling in patients with persistent AF. Female gender is associated with progressive enlargement of the left atrial and ventricle.


Although the target rate in the strict group was 110 bpm, the mean resting rate in this group was 93. It is possible that adverse remodeling would have occurred in this group if the resting rate had been closer to 110 bpm, particularly in patients with heart failure.

Keywords: Heart Atria, Follow-Up Studies, Heart Failure, Echocardiography

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