Recent clinical developments in thrombolysis in acute myocardial infarction.

Intracoronary streptokinase can accomplish reperfusion in 70 to 75% of patients with acute myocardial infarction (AMI), and intravenous streptokinase in approximately 50% of those with prior documented coronary occlusion. The time constraints for accomplishing significant myocardial salvage have proved to be quite restrictive, however. Studies in which treatment has begun after an average of 4 hours of symptoms have not shown significant improvement in ventricular function. In contrast, those in which intervention has been applied earlier, particularly in less than 2 to 3 hours, have consistently shown benefit. The price for applying thrombolytic therapy includes the risk of severe bleeding (about 5%) but, fortunately, mortality as a result of bleeding has been rare (less than or equal to 0.5%). Reperfusion may be only transient or incomplete (and insufficient). An early reocclusion rate of about 15 to 20% has been commonly noted, in fact. Recently, major studies have pointed to a reduction in early mortality in patients treated early (within about 3 hours) after the onset of symptoms. Much interest is now being focused on developing safer, more effective thrombolytic agents such as tissue plasminogen activator and anisoylated plasminogen streptokinase activator complex (APSAC). Adjunctive therapy with coronary angioplasty is also being applied. In the judgement of many, reperfusion therapy may represent the greatest advance in the approach to AMI of the current decade.