Several studies have demonstrated that myocardial infarction (MI) is likely to alter left ventricular diastolic function. However, it is unclear whether MI per se alters Doppler transmitral flow velocity patterns (TMF) clinically. To investigate how myocardial infarction alters TMF clinically, we assessed serial changes in TMF in 13 patients whose TMF patterns were recorded at a mean of 7 months before and after MI in relation to the size of MI. From TMF, early and atrial filling flow velocities (E and A (m/s), respectively), and the E/A ratio, were measured. From simultaneously recorded two-dimensional echocardiograms, left ventricular dimensions and wall motion score (WMS: sum of 17 segmental scores (dys/akinesis = 3 to normal = 0)) were determined. The patients were divided into two subsets based on the values for WMS in the convalescent stage; 8 patients had small MI (WMS < or = 10) and 5 patients had large MI (WMS > 10). In patients with small MI, although E and the E/A ratio decreased at day-1 compared with pre-MI values (pre-MI vs day-1, E; 0.54 +/- 0.12 vs 0.39 +/- 0.15, p < 0.05, E/A ratio 0.91 +/- 0.23 vs 0.68 +/- 0.14, p < 0.05), these values increased to levels similar to those observed at pre-MI in the convalescent stage. There were no changes in left ventricular dimensions between pre-MI and in the convalescent period. In patients with large MI, the changes in the TMF patterns varied among patients after MI. In 3 patients with WMS < or = 25, E and E/A ratio were decreased in the convalescent stage, compared with pre-MI values. In 2 patients with WMS > 25, TMF patterns showed 'pseudonormalization' (E/A ratio > 1.0) throughout the follow-up period, with a progressive increase in left ventricular dimension. Thus, MI per se does not always produce clear changes in the Doppler TMF pattern in clinical settings, and the size of the MI seems to be a determinant of the TMF pattern after MI.