Goals of thrombolytic therapy

In the past decade, mortality associated with acute myocardial infarction has been reduced to between 5% and 9% in selected groups of patients, largely due to use of early reperfusion. Thrombolytics combined with aggressive mechanical revascularization reduce the likelihood of death both during hospitalization and in the ensuing several years. Overall morbidity is also lessened, although salvage of patients with severe left ventricular dysfunction may make this difficult to demonstrate. Foremost among issues remaining unresolved is the relationship between patency of the infarct vessel and survival. Survival associated with reperfusion is limited primarily to patients with successful reperfusion. Myocardial salvage is more likely in these patients, but the correlation between myocardial salvage and mortality reduction is not determined. Late spontaneous reperfusion occurs in greater than 50% of patients who do not receive a thrombolytic; survival seems to be greater when vessels undergo spontaneous reperfusion. Only a minority of patients can be treated within the first hour after chest pain onset. It is not clear that the time window in which early reperfusion can be accomplished allows benefit to be clinically evident. Resources need to be directed toward agents to augment the rate of lysis and toward improvement of delivery. Mortality is highest in the first 24 hours after thrombolytic administration. Understanding of the underlying mechanisms may promote further reductions in mortality. Intravenous thrombolytic therapy can be given on average 2-3 hours after pain onset. If the myocardial salvage versus time curve is steepest immediately after occlusion, early administration of thrombolytics, such as by paramedics in the field, may be indicated.(ABSTRACT TRUNCATED AT 250 WORDS)