Long-term benefit of early thrombolytic therapy in patients with acute myocardial infarction: 5 year follow-up of a trial conducted by the Interuniversity Cardiology Institute of the Netherlands

Abstract

Patients (n = 533) who participated in the Interuniversity Cardiology Institute of the Netherlands Trial were followed up for 3 to 7 years. The 5 year survival rate after thrombolytic therapy with intracoronary streptokinase was 81% (269 patients) compared with 71% after conventional therapy (264 patients). The greatest improvement in survival was observed in patients with anterior infarction (81% versus 64% with thrombolytic therapy or conventional therapy, respectively), in those with heart failure on admission or a previous infarction and in those with extensive myocardial ischemia on admission. Left ventricular ejection fraction at the time of hospital discharge was better after thrombolytic therapy. In the hospital survivors, longterm outcome was related to left ventricular function at the time of discharge and, to a lesser extent, to the underlying coronary artery disease. The initial therapy (thrombolysis or conventional) was not an independent additional determinant of long-term survival when left ventricular function and coronary status at the time of hospital discharge were taken into account. Thus, the salutary effects of thrombolytic therapy appear to be the result of myocardial salvage.Reinfarction within 3 years was observed more frequently after thrombolytic therapy, particularly in patients with inferior wall infarction and those with ⩾90% stenosis of the infarct-related vessel at discharge. Coronary bypass surgery and coronary angioplasty were performed more frequently after thrombolytic therapy than in conventionally treated patients. At 5 years, approximately 40% of patients in both groups had an uneventful course without reinfarction or additional revascularization procedures.These observations demonstrate that the benefits of thrombolytic therapy are maintained throughout 5 years of follow-up. Treatment after hospital discharge of patients who underwent thrombolytic therapy on admission should not necessarily be different from conventional management after myocardial infarction.