The effects of intravenous thrombolytic therapy depend on maintaining the patency of infarct-related artery in acute myocardial infarction. Thirty-two patients with acute myocardial infarction and ST segment elevation were studied to determine the usefulness of early resolution of ST segment elevation as an index of recanalization after intravenous urokinase administration.

32 patients(male 24, female 8, mean age±standard deviation 62±11 years) were given intravenous urokinase therapy for acute myocardial infarction. Patients were classified into two groups according to changes of ∑ST segment elevation : early resolution(group I)=resolution to <25% of peak value within 12 hours of commencing urokinase therapy : no resolution(group II)=decreased in ∑ST segment elevation to ≥25% of peak value. The relationship between early changes in ∑ST segment elevation, time to peak creatinine kinase(CK), peak CK, changes of QRS score and & stenosis of infarct-related artery were investigated in both group.

1) The ∑ST segment elevation decreased by more than 75% of initial ∑ST within 12 hours after urokinase administration in 13 patients(40.6%). 2) The initial ∑ST segment was higher in the early resolution group than in the nonresolution group(26.0±4.2 vs 15.2±1.9mm, p<0.05). 3) The initial QRS score in both groups were not different significantly(7.2±0.9 vs 5.4±0.6 p<0.05), but QRS score decreased in the early resolution group and did not change in the no resolution group(-0.69±0.23 vs 0.63±0.16, p<0.05). 4) The early resolution group showed higher peak CK level(2409.2±347.7 vs 1445.2±280.4, p<0.05) and earlier peak time(10.6±1.0 vs 24.2±4.6, p<0.05). 5) There was no total occluded artery in both group, but the early resolution group tended to less stenosis in infarct related arteries(66.7±80 vs 86.7±3.3%, p=0.13) in predischarge coronary angiography.

Early ST resolution after intravenous urokinase administration in acute myocardial infarction is an useful clinical index of recanalization or benefit induced by thrombolytic therapy.