Prognostic significance of left atrial enlargement in a general population: results of the PAMELA study.

We estimated the risk of cardiovascular events, cardiovascular mortality, and all-cause mortality associated with left atrium (LA) enlargement alone or combined with echocardiographic left ventricular hypertrophy (LVH) in 1785 representatives of the general population of Monza recruited for the Pressioni Arteriose Monitorate E Loro Associazioni (PAMELA) study. LA enlargement was assessed by measuring LA diameter via echocardiography. LA enlargement was defined as a LA diameter>2.3 cm/m2, whereas LVH was defined as a left ventricular mass index≥114 g/m2 and 99 g/m2 in men and women, respectively. Death certificates and hospital diagnoses were collected over an average 148 months follow-up. During follow-up, there were 175 deaths (of which 59 for cardiovascular causes) and 139 cardiovascular fatal and nonfatal events. Compared with subjects with neither LA enlargement nor LVH, subjects with isolated LA enlargement exhibited a significant increase in the adjusted risk of combined fatal and nonfatal cardiovascular events (hazard ratio, 2.0; confidence interval, 1-4.1; P=0.04), although not of cardiovascular death or all-cause death. The adjusted (for baseline covariates, including ambulatory blood pressure) risk of fatal and nonfatal cardiovascular events, cardiovascular death, and all-cause death was significantly increased also in subjects with isolated LVH (hazard ratio, 2.2, 3.4, 2.1, respectively; P=0.001 for all), whereas no further increase was seen in subjects with both LA and left ventricular abnormalities. Thus, like LVH, LA enlargement is an independent long-term predictor of cardiovascular events. The cardiovascular risk, however, is not further increased when LA enlargement is superimposed on an increase of LV mass.