Thrombolytic therapy in acute myocardial infarction.

Thrombolytic trials in acute myocardial infarction have progressively increased in size, with the GUSTO study including over 40,000 patients. New thrombolytic drugs are unlikely to lead to further major reductions in fatality, and demonstrating small differences from existing compounds would require even larger trials to establish mortality benefits. New agents may, however, have advantages, such as a greater ease of administration or a reduced cost, and the problem is how to assess such new agents in the most efficient way. The concept of equivalence as a clinical trial endpoint is discussed, and the INJECT study, comparing reteplase and streptokinase in acute myocardial infarction, is described as a prototype equivalence trial.