Regional and systemic thrombolytic therapy in acute myocardial infarction.

Thrombolytic therapy has emerged as a promising approach in the management of patients with acute myocardial infarction. Intracoronary infusion can achieve patency in a high percentage of patients with evolving transmural infarction, and recent preliminary evidence indicates that reperfusion may also be achieved in a substantial but lower percentage of patients with intravenous administration. The relative safety and the efficacy in restoring flow in selected patients seem established, and there is considerable evidence that successful thrombolysis with early reperfusion is associated with salvage of ischemic myocardium as determined by improvement in left ventricular function and by myocardial perfusion imaging. However, a number of important issues remain unresolved. The technique of intracoronary administration is not standardized, and optimal methodology is unknown. The most appropriate dosages for both regional and systemic infusion that will provide maximal reperfusion rates with minimal complications are undefined. Guidelines for patient selection need refinement as the time limits for beneficial effects are unclear, and current usage has been restricted to patients with transmural infarction. Improved survival following intervention has not been clearly established, and further evaluation of long-term effects is needed. Early reocclusion and reinfarction are not uncommon after thrombolysis and indicate that this approach does not represent definitive therapy in a significant percentage of patients and that additional intervention may be necessary to achieve permanent myocardial salvage. The sequence and timing of adjunctive therapy to prevent reocclusion have not been clearly determined. In addition, the relative efficacy of systemic and regional administration requires further evaluation. A number of prospective randomized controlled studies that are currently underway or planned address many of these unresolved issues and should more clearly define the role of thrombolytic therapy in the management of patients with acute myocardial infarction.