Left ventricular (LV) diastolic function is an important predictor of morbidity and mortality after acute myocardial infarction (AMI). We evaluated the role of diastolic function in predicting in-hospital events and LV ejection fraction (EF) 6 months after a first AMI that was treated with primary percutaneous coronary intervention (PCI). We prospectively enrolled 59 consecutive patients who were 60 +/- 15 years of age (48 men), presented at our institution with their first AMI, and were treated with primary PCI. Patients underwent 2-dimensional and Doppler echocardiography, including tissue Doppler imaging of 6 basal mitral annular regions within 24 hours after primary PCI and were followed until discharge. Clinical and echocardiographic variables at index AMI were compared with a combined end point of cardiac death, ventricular tachycardia, congestive heart failure, or emergency in-hospital surgical revascularization. Follow-up echocardiographic assessment was performed at 6 months in 24 patients. During hospitalization, 3 patients died, 7 developed congestive heart failure, 4 had ventricular tachycardia, and 1 required emergency surgical revascularization. Stepwise logistic regression analysis showed the ratio of early mitral inflow diastolic filling wave (E) to peak early diastolic velocity of non-infarct-related mitral annulus (p < 0.01) (E') and mitral inflow E-wave deceleration time (p < 0.02) to be independent predictors of in-hospital cardiac events (generalized R2 = 0.66). In a stepwise multiple linear regression model, independent predictors of follow-up LVEF were mitral inflow deceleration time (R2 = 0.39, p = 0.002), baseline LVEF (R2 = 0.54, p < 0.02), and mitral inflow peak early velocity/mitral annular peak early velocity (or E/E') of infarct annulus (R2 = 0.66, p = 0.02). In conclusion, in patients who are treated with primary PCI for a first AMI, E/E' velocity ratio and mitral inflow E-wave deceleration time are strong predictors of in-hospital cardiac events and of LVEF at 6-month follow-up.