Left atrial diameter in nonvalvular atrial fibrillation: An echocardiographic study

Background The left atrium (LA) is usually enlarged in patients with nonval vulor atrial fibrillation (AF), but factors associated with LA diameter ore incompletely defined. Methods and Results This transthoracic echocardiographic cohort study inclu des 3465 participant. with nonvalvular AF In 3 multicenter clinical trials. LA diameter determined by M-mode echocardiography was correlated with clin ical and echocardiographic features by cross-sectional multivariate regress ion analyses. The mean LA diameter was 47 +/- 8 mm, on average 6 mm larger in those with AF at the time of echocardiography than in those with sinus r hythm (48 vs 42 mm, P <.001). Patient age and body weight were independentl y predictive of LA diameter (P <.0007), but sex, body surface area, and bod y mass index were not. The estimated independent contribution of atrial rhy thm to LA diameter was approximately 2.5 mm. Prolonged duration pf AF, left ventricular dilatation find increased muscle mass; mitral regurgitation, a nnular calcification, and hypertension were additional independent predicto rs of LA diameter. Conclusions Multiple factors appear to contribute to LA enlargement in pati ents with nonvalvular AF, including the presence and persistence of the dys rhythmia.