EXTENT OF EARLY ST SEGMENT ELEVATION RESOLUTION - A STRONG PREDICTOR OF OUTCOME IN PATIENTS WITH ACUTE MYOCARDIAL-INFARCTION AND A SENSITIVE MEASURE TO COMPARE THROMBOLYTIC REGIMENS - A SUBSTUDY OF THE INTERNATIONAL JOINT EFFICACY COMPARISON OF THROMBOLYTICS (INJECT) TRIAL

Objectives. This study was undertaken to assess prospectively the prog nostic power of early ST segment elevation resolution in a large cohor t of patients with myocardial infarction and to test the value of diff erences in ST segment resolution as a surrogate end point. Background. Previous studies revealed that the use of two cutoff points for three groups of ST segment resolution within 3 h after the start of thrombo lysis is most effective in predicting outcome. Methods. The Internatio nal Joint Efficacy Comparison of Thrombolytics (INJECT) trial compared mortality in 6,010 patients randomized to receive either reteplase or streptokinase. The 1,909 German patients form the basis of this subst udy. The three groups of ST segment resolution were defined as complet e (greater than or equal to 70%), partial (70% to 30%) and no resoluti on (<30% to greater than or equal to 0%). Results. In 1,398 patients p resenting less than or equal to 6 h from onset of acute myocardial inf arction, the 35-day mortality rate for complete, partial and no ST seg ment resolution was 2.5%, 4.3% and 17.5%, respectively (p < 0.0001). P eak creatine kinase levels (fraction of normal) were 9.8, 13.4 and 14. 0, respectively (p < 0.0001), When baseline characteristics were inclu ded, ST segment resolution was the most powerful independent predictor of 35-day mortality. The proportion of patients with complete ST segm ent resolution was larger, and that with no ST segment resolution smal ler, with reteplase than with streptokinase (p = 0.006). Conclusions. No ST segment resolution, indicating failed thrombolysis, predicts ver y high early mortality, whereas com plete resolution is associated wit h a small infarct area and low mortality. Partial ST segment resolutio n also predicts larger infarct areas, but early mortality is relativel y low, Different extents of ST segment resolution may serve as a sensi tive surrogate end point in clinical trials. (J Am Coll Cardiol 1995;2 6:1657-64)