Thrombolytic therapy for myocardial ischemia and infarction

Thrombolysis during the early hours of a myocardial infarction significantly improves patient survival in a hospital. Beyond 6 hours, up to 24 hours, thrombolysis may still contribute to a reduction in mortality. However, further confirmation is desirable before such therapy late in the course of an evolving infarct can be routinely recommended. Although clot-specific agents such as recombinant tissue-type plasminogen activator (rt-PA) produce a higher initial patency rate, reocclusion rates are higher in the absence of the profound systemic fibrinolysis produced by agents such as streptokinase. This may explain the GISSI-2 results where 15-day survival was no different between the streptokinase- and rt-PA-treated subjects. Although the manner of heparin administration may have clouded these results, current research is directed toward looking at combinations of thrombolytic agents that would combine drugs efficient in producing early patency with those that produce a more pronounced fibrinolytic state. More effective adjunctive therapy is also under intense investigation, particularly specific antithrombin agents that would produce more effective anticoagulation following thrombolysis, and more effective antiplatelet agents that would help prevent reocclusion.