Routine invasive evaluations are being abandoned, and thus simple non-invasive methods for estimating the extent of jeopardized myocardium during evolving myocardial infarction are needed for risk stratification to guide the appropriate therapeutic intervention. With this in mind the aim of the paper was to evaluate the association between ischaemic changes in the standard electrocardiogram and the function of acutely infarcted myocardium in relation to infarct artery patency status. Forty consecutive patients with a first acute myocardial infarction, admitted within 6 h of symptom onset and without bundle branch or fascicular block were included. Summated ST segment elevation in 11 electrocardiographic leads (aVR excluded) was measured to the nearest 0.05 mV and compared to regional wall motion, estimated by the centreline method (SD/chord) and global left ventricular ejection fraction (% LVEF) after thrombolytic therapy. Acute angiographic and ST segment measurements were performed at a median 254 min (range 70-485) after the onset of symptoms. Patients were grouped according to infarct artery patency status after intravenous thrombolysis. Of the 40 patients, 27 had a patent (Thrombolysis In Acute Myocardial Infarction trial (TIMI) grade 2-3 flow) and 13 had persistently occluded (TIMI 0-1 flow) infarct arteries. Anterior myocardial infarction was present in 13 and seven patients in the two groups. In the TIMI 2-3 group, the summated ST elevation did not correlate with % LVEF or SD/chord (rs = -0.08; and rs = -0.17, respectively). In the TIMI0-1 group the summated ST elevation correlated inversely with both % LVEF and SD/chord (rs = -0.70; and rs = -0.56, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)