Distortion of the terminal portion of the QRS on the admission electrocardiogram in acute myocardial infarction and correlation with infarct size and long-term prognosis (Thrombolysis in Myocardial Infarction 4 Trial).

Previous studies have shown an association between distortion of the terminal portion of the QRS (QRS[+] pattern: emergence of the J point > or = 50%. of the R wave in leads with qR configuration or disappearance of the S wave in leads with an Rs configuration) on admission and in-hospital mortality in acute myocardial infarction (AMI). However, the mechanism for this association is not known. We assessed the relation between QRS(+) pattern and coronary angiographic findings, infarct size, and long-term prognosis in the Thrombolysis In Myocardial Infarction 4 trial. Patients were allocated into 2 groups based on the presence (QRS[+], n = 85) or absence (QRS[-], n = 293) of QRS distortion. The QRS(+) patients were older (mean +/- SD: 61.1 +/- 10.6 vs 57.5 +/- 10.6 years, p = 0.004), had more anterior AMI (49% vs 37%, p = 0.04), and less previous angina (42% vs 54%, p = 0.05). QRS(+) patients had larger infarct size as assessed by creatine kinase release over 24 hours (209 +/- 147 vs 155 +/- 129, p = 0.003), and predischarge sestamibi (MIBI) defect (17.9 +/- 15.9% vs 11.2 +/- 13.4%, p <0.001). When adjusting for difference in baseline characteristics, p values for the differences in 24-hour creatine kinase release were 0.03 and 0.64 for anterior and nonanterior AMI, respectively, and for MIBI defect size 0.03 and 0.02, respectively. One-year mortality (18% vs 6%, p = 0.03) was higher and the weighted end point of death, reinfarction, heart failure, or left ventricular ejection fraction <40% (0.33 +/- 0.37 vs 0.24 +/- 0.32, p = 0. 13), tended to be higher in the anterior AMI patients with QRS(+). No difference in clinical outcome was found in patients with non-anterior AMI. These findings suggest that this simple electrocardiographic definition of presence of QRS(+) pattern on admission may provide an early estimation of infarct size and long-term prognosis, especially in anterior AMI.

RCT Entities:   Population Interventions Outcomes