Prognostic significance of the extent of myocardial injury in acute myocardial infarction treated by streptokinase

The effect of site and extent of an infarct, an area of dead tissue caused by lack of blood flow to a portion of an organ, on therapeutic outcome and effectiveness of thrombolytic therapy (dissolving blood clots with drugs) was evaluated in 8,713 cases of acute myocardial infarction (heart attack). The use of the thrombolytic agent streptokinase significantly reduced the chance of death. The risk of death increased as the size of the infarct site increased. In small infarcts there was a 6.5 percent mortality rate, a 9.5 percent rate in modest, a 14.3 percent rate in large, and a 21.7 percent rate in extensive infarctions. Streptokinase was not beneficial in small infarcts, but was very effective in larger infarcts. The extent of injury seems to be more relevant than the site of occurrence to the risk of death and the effectiveness of thrombolytic therapy.