Is the outcomes of early ST-segment resolution after thrombolytic therapy in acute myocardial infarction always favorable?

AIMS: To determine whether the magnitude of ST-segment resolution after thrombolytic therapy (TT) predicts short- and long-term outcomes in an unselected population of patients with an acute myocardial infarction (AMI). BACKGROUND: Recent studies suggest that resolution of ST-segment elevation (STE) on the 2-hour post-TT electrocardiogram (ECG) is a useful predictor of prognosis. However, these studies were restricted to clinical trials where only 15% to 20% of the patients receiving TT were often enrolled. METHODS: The present study evaluated an unselected consecutive group of patients who received TT. All clinical, investigational, and follow-up data had been collected in a prospective manner. The analysis of ECGs was done retrospectively with the reader blinded to the clinical course. STE at 80 milliseconds after the J point was measured on the baseline and 90-minute ECG using a hand-held caliper. The resolution of STE was categorized as complete (>or=70%), partial (30% to <70%), and none (<30%) as has been done in previous studies. RESULTS: Three hundred fifty-two patients (250 men, 102 women; age, mean+/-SEM, 61.8+/-1.0 years; peak creatine kinase, 1938+/-185 micromol/L; door to needle time, 50.0+/-6 minutes, <30 minutes, 50%; <45 minutes, 70%) with AMIs who received TT were included in the study. Inhospital deaths and recurrent AMI/postinfarct angina revealed no significant association with increasing ST-segment resolution (P>.05). A 70% or higher ST-segment resolution was associated with a significantly lower incidence of inhospital congestive heart failure (CHF) and CHF/death (P<.05). Similarly, with a 70% or higher ST-segment resolution, there was a lower incidence in the 1-year outcomes of CHF and death/CHF. However the 1-year occurrences of unstable angina or recurrent AMIs taken singly did not bear a correlation to increasing magnitudes of ST-segment resolution (P>.05). Although as a composite measure, there was an increasing trend with ST-segment resolution. CONCLUSIONS: Magnitude of ST-segment resolution after TT appears to demonstrate a dichotomous relationship to measured outcomes. Although there is a lower incidence of death/CHF with increasing ST-segment resolution, there appears to be a higher likelihood for recurrent AMI/unstable angina.