Effects of intracoronary thrombolysis on infarct size and left ventricular function in patients with anterior myocardial infarction--enzymatic, electrocardiographic, radionuclide and hemodynamic evaluations.

The influence of the duration of ischemia on infarct size and left ventricular function (LV) was assessed in 30 patients with a first anterior myocardial infarction (MI) and intracoronary thrombolysis (ICTL) on admission. The occlusion time of the left anterior descending coronary artery (LAD) was 4 hours or less in 11 patients (group I), 4-10 hours in 11 (group II) and 10 hours or more in eight (group III). Serial measurements of serum creatine kinase-MB were carried out during the acute phase. Four weeks after the procedure, electrocardiographic pathological Q waves on 34-lead precordial mapping were scored, viable left ventricular myocardial volume and the ratio of infarcted to total left ventricular myocardial volume was estimated by myocardial emission computed tomography (ECT) with thallium-201. In the acute phase enzymatic estimation of infarct size showed a significant difference between group I and the other two groups but not between groups II and III; there were no significant differences in the degree of left ventricular asynergy among the three groups. In the chronic phase infarct sizes evaluated by both Q wave mapping and ECT were smaller in group I than those in group II, which were smaller than those in group III; there were significant differences in the degree of LV asynergy among the three groups (group I less than II less than III). LV function was nearly normal in group I, moderately impaired in group II, but severely depressed in group III 4 weeks later. The present study indicates that infarct size extends and LV function deteriorates with the duration of occlusion of the LAD and that not only early (less than or equal to 4 hours) but also later (4-10 hours) reperfusion is beneficial to prevent the extension of MI and deterioration of LV function in patients with anterior MI.