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/m². 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 electrocardiographic, 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.