Background : In chronic mitral regurgitation (MR), left atrium (LA) is affected by pressure and volume overload. We investigated impact of pressure and volume overload on the LA remodeling in chronic mitral regurgitation. Methods : We reviewed 130 patients, mean age 56짹17 years, with varying grades of chronic MR due to myxomatous mitral valve disease and in sinus rhythm, with preserved left ventricular systolic function, no history of ischemic heart disease using transthoracic Doppler echocardiography. We used LA eccentricity index (LAEi) and LA volume index (LAVi) to estimate LA morphology and size. LAEi was calculated from 3 dimensions of left atrium. : anteroposterior (D1), superoinferior (D2), mediolateral (D3), and LAEi=D2x2/D1+D3. LA volumes were measured using ellipsoid method, and indexed to body surface area. Results : In a multivariate analysis, RF was independently associated with LA eccentricity (p<0.001, r=-0.604). LVMI (p<0.001, r=0.634), RF (p<0.001, r=0.608) and E/A (p<0.001, r=0.338) positively correlated with LAVi. Also, LAVi and LAEi showed inverse relation (p<0.001, r=-0.461) (Table 1). Conclusion : LA eccentricity is mainly affected by volume rather than pressure overload. LAEi may be used to predict atrial fibrillation or cardiovascular risk in patients with chronic MR as LAVi. Key words : chronic mitral regurgitation, LA remodeling, LA eccentricity index