AIM: The administration of thrombolytic therapy after an acute myocardial infarction can reduce the size of the infarct and improve left ventricular function. We used pulsed Doppler to assess left ventricular diastolic function after an acute myocardial infarction in patients treated with recombinant tissue plasminogen activator (rTPA). PATIENTS AND METHODS: We studied 104 patients after an acute myocardial infarction, 48 treated with a placebo and 56 with rTPA. They were compared with 36 age-matched controls. The Doppler parameters measured included the early peak in diastolic flow velocity, the peak during atrial contraction, the atrial: early ratio, mean deceleration, deceleration time, and half-filling fraction. Doppler parameters for large and small infarct sizes were compared. RESULTS: The Doppler parameters did not differ between treatment groups. Compared with the normal controls, significant differences were observed in both treatment groups for the early peak (placebo P < 0.05; rTPA P < 0.001), the atrial: early ratio (placebo P < 0.05; rTPA P < 0.01), and the half-filling fraction (P < 0.001 for both). In patients with large infarcts, the atrial peak was depressed (P = 0.008). Multivariate analysis showed that end-diastolic pressure, age, end-systolic volume, and regional wall motion parameters were major predictors of Doppler parameters.