Does Grade 3 Ischemia on Admission Electrocardiogram Predict the ST Segment Resolution Following Thrombolysis in ST Elevation Myocardial Infarction?

Background: ST segment resolution (STR) following reperfusion therapy in STEMI patients has been shown to be a very strong predictor of outcome. Several studies investigated the strength of terminal QRS distortion (grade 3 ischemia) in predicting the failure of STR after reperfusion therapy. This study aimed to investigate whether grade 3 ischemia or other clinical characteristics could predict STR or not. Methods: In this cross-sectional study, we enrolled 100 consecutive acute STEMI patients who were admitted during 12 hours after the onset of their chest pain. Baseline clinical characteristics, electrocardiogram at 90 min, 3 hours, and 24 hours after the initiation of thrombolysis therapy, and echocardiographic data were retrived from the patients’ medical records. Results: The mean age of patients was 59±12 years old (13-93 years). Eighty percent were men and 46% were smoker. Thirty eight (38%) patients had grade 3 ischemia on their admission electrocardiogram. The frequency of grade 3 ischemia was different among patients with and without STR at 90 min (P=0.01), 3 hours (P=0.04), and 24 hours (P=0.04) after the thrombolytic therapy. But when comparing the outcome of patients with grade 2 and 3 ischemia on admission ECG, there was no significant difference in the frequency of complete STR between two groups in different time points. Only the frequency of failure to STR (STR 30%) was different among patients with grade 2 and 3 ischemia, 24 hours after thrombolysis (P=0.03). Odds ratio for grade 3 ischemia in predicting failure to STR was 1.80 (with 95% CI: 0.6-5.2). Conclusions: The presence of grade 3 ischemia on admission electrocardiogram was predictor of incomplete STR at 90 min, 3 h and 24 h after the initiation of thrombolysis and was associated with higher rates of coronary angiography and angioplasty.