Is the outcomes of early ST-segment resolution after thrombolytic therapy in acute myocardial infarction always favorable?
OBJECTIVE
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.
Bainey
Kevin R
KR
Division of Cardiology, Grey Nuns Hospital, Edmonton, Alberta, Canada T6L 5X8.
Senaratne
Manohara P J
MP
D002170:Canada / Q000453:epidemiology; D015897:Comorbidity; D004562:Electrocardiography / Q000379:methods / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000188:drug therapy* / Q000453:epidemiology; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011379:Prognosis; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D016037:Single-Blind Method; D013223:Statistics as Topic; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control; D015912:Thrombolytic Therapy / Q000706:statistics & numerical data*; D016896:Treatment Outcome