Serial myocardial lactate metabolic changes after intracoronary thrombolysis in evolving myocardial infarction.

To investigate whether early reperfusion (less than or equal to 3 hours) preserves aerobic myocardial metabolism in acute myocardial infarction, we examined serial changes in trans-cardiac lactate extraction after thrombolysis in 43 patients with acute antero-septal myocardial infarction. In the chronic phase, we also determined abnormally contracting segments as an index of infarct size and regional ejection fraction as an index of chronic regional cardiac function. In the early reperfusion group (less than or equal to 3 hours), positive lactate extraction was restored and there were small abnormally contracting segments and a high regional ejection fraction. The intermediate reperfusion group (3-5 hours), however, had sustained anaerobic lactate extraction, large abnormally contracting segments and a low regional ejection fraction. The late reperfusion (greater than 5 hours) group showed apparently aerobic lactate extraction, but had large abnormally contracting segments and a low regional ejection fraction. Thus, early reperfusion preserves aerobic lactate metabolism and good chronic ventricular function.