The importance of infarct expansion in determining global ventricular remodelling and prognosis after myocardial infarction is well known, whereas how infarct expansion affects left ventricular filling dynamics is not defined. To address this issue two-dimensional and Doppler echocardiography was performed in 28 consecutive patients admitted to our Coronary Care Unit for a first acute transmural myocardial infarction 1) within 24 hours of symptoms' onset and 2) at predischarge. A semiquantitative echocardiographic infarct size index was computed, while the infarct and non-infarct segment length was measured in a short-axis papillary muscle section. Peak velocity of early (E) and late (A) transmitral Doppler curves were also measured. An increment in infarct segment length > or = 1.2 cm between baseline and predischarge examination was chosen as target to divide patients with (N = 8) and without (N = 20) infarct expansion. Patients with expansion had a higher echocardiographic infarct size index (3.5 +/- 1.4 versus 2.3 +/- 0.6 segments, p < 0.0001) and a higher CK-MB infarct size (336 +/- 235 versus 129 +/- 87 UI, p = 0.002), while ejection fraction was lower (36 +/- 8% versus 48 +/- 7%, p < 0.001). A linear correlation was found between the increment in infarct segment length and in left ventricular volume between the baseline and the predischarge examination (r = 0.58, p < 0.01). Doppler parameters were not different at baseline examination between patients with and without expansion.(ABSTRACT TRUNCATED AT 250 WORDS)