Objectives: This study proposed to verify the prognostic power of early ST segment elevation resolution in patients with acute myocardial infarction from the Intravenous Streptokinase in Acute Myocardial Infarction study data base.
Background: Data from a small prospective study suggested that use of two cutoff points for three different levels of ST segment resolution 3 h after the start of thrombolysis may be an efficient way to predict outcome in an individual patient.
Methods: The three groups of ST segment resolution were defined as 1) complete resolution (> or = 70% [552 patients]) or only slight ST segment elevation (127 patients); 2) partial resolution (< 70% to 30% [475 patients]); 3) no resolution (< 30% to > 0% [362 patients]). Infarct size was measured from creatine kinase isoenzyme, MB fraction, release and from the number of Q waves. Left ventricular function was assessed in 818 patients 1 month after infarction.
Results: For complete, partial and no ST segment resolution 3 h after the start of streptokinase or placebo infusion, enzyme release was 1.2, 1.8 and 2.1 IU/ml x h; number of Q waves 1.7, 2.5 and 3.0; and ejection fraction 60%, 53% and 49%, respectively (all adjusted p = 0.0000). Mortality rate at 21 days was 2.2%, 3.4% and 8.6%, respectively. No ST segment resolution was the most powerful independent predictor of early mortality (p = 0.0001). Survival rate curves at 6-year follow-up showed significant mortality differences with increasing divergence (p = 0.0003 anterior infarction; p = 0.005 inferior infarction). In subgroups with an overall higher risk of dying, mortality was strongly determined by the extent of early ST segment resolution.
Conclusions: The extent of ST segment elevation resolution conveys useful early information about outcome in an individual patient after acute myocardial infarction.