Effect of rate and rhythm control on left ventricular function and cardiac dimensions in patients with persistent atrial fibrillation: Results from the RAte Control versus Electrical cardioversion for persistent atrial fibrillation (RACE) study

OBJECTIVES The purpose of this study was to evaluate left ventricular function and atrial and ventricular diameters in patients with persistent atrial fibrillation (AF) treated with rate or rhythm control. BACKGROUND Restoration of sinus rhythm inpatients with persistent AF may improve left ventricular function and reduce atrial dimensions. Adequate rate control in AF may preserve ventricular function. METHODS In 335 patients included in the RAte Control versus Electrical Cardioversion for Persistent Atrial Fibrillation (RACE) study, echocardiography was performed at baseline and 1- and 2-year follow-up. Echocardiography was compared between patients randomized to rate control (n = 160) and rhythm control (n = 175). In the rhythm control group, echocardiography was compared between patients with AF versus sinus rhythm at study end. Multivariate analysis was performed to determine parameters related to improvement of left ventricular function and increase of atrial diameters. RESULTS Fractional shortening improved significantly under rate and rhythm control (31 - 10% at baseline to 33 +/- 9% at 2 years, and from 30 - 10% to 34 - 9%; both P < .05, respectively). Under rate control, left and right atrial size increased significantly compared to baseline. Under rhythm control, only left atrial size increased. Multivariate analysis revealed that only sinus rhythm at study end was associated with an increase of fractional shortening. AF at study end, hypertension, and no use of angiotensin-converting enzyme inhibitors were independently associated with increase in atrial size. CONCLUSIONS Routine rate control prevents deterioration of left ventricular function. Maintenance of sinus rhythm is associated with improvement of left ventricular function and reduction of atrial sizes.