Echocardiographic left atrial (LA) volume has been documented to be an independent predictor of cardiovascular events. Less is known about the predictive ability of anteroposterior LA diameter, a simpler measure of LA size obtained routinely during echocardiographic evaluation.

We investigated the prognostic value of LA diameter for incident cardiovascular events in 2804 American Indians free of clinical cardiovascular disease, valvular disease, and atrial fibrillation. Echocardiographic variables were obtained using standardized methods, and previously derived sex-specific partition values were used to define left ventricular (LV) hypertrophy indexed to height^2.7 (in meters) and LA enlargement (>4.2 cm in men, >3.8 cm in women). Cardiovascular events included nonfatal stroke, coronary heart disease, congestive heart failure, and fatal cardiovascular disease based on validated definitions.

During a median follow-up of 7 years, 368 events occurred. LA diameter, both as a continuous and as a categorical variable, was significantly associated with incident cardiovascular events in unadjusted analyses. In multivariable analyses that adjusted for age, sex, body mass index, hypertension, diabetes, total cholesterol–high-density lipoprotein cholesterol, smoking, renal insufficiency, LV hypertrophy, abnormal LV systolic and diastolic function, mitral annular calcification, fibrinogen, and C-reactive protein, both LA diameter (risk ratio 1.04/mm, 95% CI 1.02-1.07, P < .002) and LA enlargement (risk ratio 1.57, 95% CI 1.17-2.10, P = .002) remained independent predictors of first cardiovascular events.

In this population-based cohort, LA diameter independently predicted incident cardiovascular events after adjustment for established clinical, echocardiographic, and inflammatory risk factors. This simple measure of LA dilatation can identify individuals at heightened risk who may warrant more aggressive risk factor modification.