Background: Experimental studies showed myocardial viability may influence on the diastolic function of left ventricle(LV) in the early phase after acute coronary syndrome(ACS). But there were few reports about this relationship in human. Methods: 93 consecutive patients with ACS and akinetic wall motion in at least two segments underwent low dose dobutamine stress echocardiography(upto 10mcg/kg/min) to assess myocardial viability on 7짹2 days after the event. Myocardial viability was quantitatively evaluated by a strain rate imaging parameter, the percent change of time to the onset of regional relaxation(T_R) as well as wall motion score index. At the same time, various echocardiographic diastolic parameters were measured. Within 6 hours after the study, left and right heart catheterizations for recording of pressures were performed. Myocardial viability index(MVI) was newly devised as a multiplicaion of numbers of akinetic segment and binary viability determinant by the percent change of T_R. Results: Patients(68.8% men, mean age 59.9짹1.3 years, 59.2% anterior wall, 48.9% ST-segment elevation) were tolerated low dose dobutamine stress echocardiography without significant complications. MVI showed significant linear correlations with left atrial volume index, duration of pulmonary venous atrial flow reversal, deceleration time of transmitral E wave, systolic fraction of pulmonary venous flow and transmitral peak E /mitral annular peak E���velocity ratio(r=0.44, p=0.00 and r=0.31, p=0.00 and r=-0.29, p=0.01 and r=-0.25, p=0.02 and r=0.22, p=0.04, respectively). Also, interestingly, MVI showed significant linear correlation with invasive pulmonary capillary wedge pressure(r=0.72, p=0.00). But changes of wall motion score index didn���t showed any significances in correlation with diastolic functional parameters. Conclusions: Novel MVI correlates with LV diastolic functional parameters reflecting chamber remodeling after ACS. So, MVI acquired by strain rate imaging on low dose dobutamine stress echocardiography may provide a useful prognostic information for LV remodelling in the early phase of ACS.