An Individual Approach to Thrombolytic Therapy in Patients with Evolving Myocardial Infarction

In recent years different regimens for reperfusion therapy in evolving myocardial infarction have been developed: intravenous streptokinase, accelerated tPA and direct angioplasty. The life saving effect of thrombolytic therapy has been established in a number of randomized trials, most of which tested streptokinase 1.5 million units administered over l h. The results have been summarized in the report of the fibrinolytic therapy trialists. 1 In patients treated within 6 h after the onset of symptoms an overall treatment benefit of 28% has been observed, while a smaller benefit (12.5%) can be achieved by treatment between 6 and 12 h after symptom onset. 2'3 Two studies showed no difference between streptokinase and alteplase or duteplase given without heparin or with delayed administration of subcutaneous heparin. 4'5 In contrast, the GUSTO study clearly demonstrated improved survival (mortality reduction 18%) by accelerated tPA, administered over 90 min, with high dose intravenous heparin. 6 The GUSTO angiographic substudy confirmed that a greater benefit by accelerated tPA was caused by higher early reperfusion rates obtained by that regimen, while later patency rates (3 h or more after onset of therapy) were similar for the different regimens. 7'8 Three recent studies have shown more rapid reperfusion by direct angioplasty, associated with better survival compared with thrombolytic therapy. 9-12 The proportion of patients with adequate (TIMI grade III) perfusion at various intervals after the onset of therapy is illustrated in Figure I. Unfortunately the more effective regimens (accelerated tPA versus streptokinase and direct angioplasty versus thrombolytic therapy) are also more expensive and more complex. Because of budgetary constrains it will often not be possible to provide the best (and most