[What have we learned from large trials?]

Clinical trials, during myocardial infarction, showed the importance of thrombolytic therapy on coronary patency, to improve left ventricular function, to reduce early and late mortality. Since the efficacy of thrombolytic therapy is now well established, most clinical trials were made to compare the efficacy of SK, rt-PA and APSAC and to evaluate concomitant drugs. Recanalization and coronary patency, reocclusion and incidence of side effects, left ventricle function's improvement and lowered mortality have been used to assess drugs' activity. At the moment the efficacy of three thrombolytic drugs seems to be the same. So the drug's choice is related not to drug's efficacy but to side effects of the drugs. Concomitant intravenous heparin therapy is now under study; utility of this therapy is shown by its theoretical assumptions and by clinical trials results. Large clinical trials are working to extend our knowledge, improving the patients' management in our every day clinical practice. Furthermore, large trials do not replace but go together with studies performed on few patients, whose results often give advance notice of those of large ones.