Background: It is clinically important to predict myocardial viability in acute myocardial infarction(AMI). It is known that coronary flow reserve(CFR) shows microvascular integrity and more impaired microvascular integrity may be related to more damaged myocardium. Recently, myocardial deformation can be evaluated by strain rate imaging(SRI). The purpose of this study was to evaluate the relation between SRI and CFR in assessing myocardial viability in AMI. Methods: Twenty patients(55 짹 11years) with first diagnosed AMI who had single infarct related coronary artery(11 patients with LAD) and underwent primary percutaneous intervention were enrolled. In 3~5 days after revascularization, SRI were acquired with frame rate of >200/s for each left ventricular walls from apical view. Systolic and diastolic SR and systolic strain(S) were obtained from infarcted akinetic walls and remote normal walls. In the same day, CFR was obtained invasively from infarct related coronary artery with a 0.014-inch Doppler guidewire(Cardiometrics FloWire). Follow up echocardiography in 6~8 weeks was done to determine myocardial recovery from AMI. Results: All systolic and diastolic SR and S were significantly lower in akinetic walls than remote walls. Recovered walls showed larger systolic SR(-0.44짹0.09 vs. -0.29짹0.13 1/s,p=0.01), early diastolic SR(0.75짹0.38 vs. 0.46짹0.23 1/s,p=0.05) and S (-6.5짹3.6 vs. -2.1짹4.9%,p=0.04) than non-recovered walls. However, postsystolic shortening SR and strain were not significantly different(p=0.16 and p=0.50, respectively). CFR was also higher in recovered patients (2.2짹0.5 vs. 1.6짹0.4,p=0.008). And CFR was significantly correlated with systolic SR (r= -0.64, p=0.003), early diastolic SR (r= 0.66,p=0.004) and S (r= -0.66,p=0.002). Multiple regression analysis showed S and early diastolic SR were most related to CFR (r2=0.59,p<0.001). Conclusion: The AMI patients with recovery had better systolic & early diastolic SR, systolic S and CFR. Moreover CFR was strongly related to systolic S and early diastolic SR. These findings suggest that the akinetic myocardium with less impaired microvascular integrity has more preserved systolic and diastolic myocardial function, which is viable.