Role of left atrial size in risk stratification and prognosis of patients undergoing stress echocardiography

Objectives The purpose of this study was to evaluate the role of diastolic dysfunction as measured by left atrial (LA) size in patients undergoing stress echocardiography (SE). Background Left atrial size is a surrogate marker of diastolic function. However, its prognostic value in patients referred for SE is not well defined. Methods We evaluated 2,705 patients (60 +/- 13 years, 47% men) undergoing SE (56% dobutamine). Patients with significant mitral valve disease (mitral stenosis or moderate mitral regurgitation) were excluded. Enlarged LA was defined as a LA size indexed to body surface area >= 2.4 cm/m(2). Follow-up (mean 2.7 +/- 1.0 years) for nonfatal myocardial infarction or cardiac death (n = 122) was obtained. Results A dilated LA was able to further risk-stratify both the normal and abnormal SE groups. In the presence of a dilated LA, an abnormal SE portends a worse prognosis compared with patients with normal LA size. Cox proportional modeling showed that a dilated LA added incremental value over traditional risk factors, stress electrocar-diographic, rest echocardiographic, and SE variables for the prediction of hard events (global chi-square increased from 90.4 to 113.1 to 176.1 to 184.4 to 190.5; p < 0.05 all groups). Left atrial size was a significant predictor of events independent of left ventricular systolic dysfunction and ischemia (relative risk = 1.84, 95% confidence interval 1.19 to 2.85; p = 0.006). Conclusions In patients referred for stress echocardiography, LA size provides independent and incremental value over standard risk factors including left ventricular systolic dysfunction and ischemia. Left atrial size is a powerful prognosticator and should be routinely used in the prognostic interpretation of stress echocardiography.