Prognostic value of predischarge electrocardiographic measurement of infarct size after thrombolysis: Insights from GUSTO I Economics and Quality of Life substudy

Abstract

Background Current methods for risk stratification after acute myocardial infarction (MI) include several noninvasive studies. In this cost-containment era, the development of low-cost means should be encouraged. We assessed the ability of an electrocardiogram (ECG) MI-sizing score to predict outcomes in patients enrolled in the Economics and Quality of Life (EQOL) sub study of the Global Utilization of Streptokinase and Tissue plasminogen activator for Occluded coronary arteries –I (GUSTO-I) trial. Methods We classified patients by electrocardiographic Selvester QRS score at hospital discharge: those with a score 0–9 versus ≥10. Endpoints were 30-day and 1-year mortality, resource use, and quality-of-life measures. Results Patients with a QRS score <10 were well-matched with those with QRS score ≥10 with the exception of a trend to more anterior MI in the higher scored group. Patients with QRS score ≥10 had increased risk of death at 30-days (8.9% vs. 2.9% P < .001), and this difference persisted at 1 year (12.6% vs. 5.4%, P = .001). Recurrent chest pain, use of angiography, and angioplasty were similar during follow-up. However, there was a trend toward less coronary bypass surgery in patients with a QRS score ≥10. Readmission rates were higher at 30 days but similar at 1 year. Conclusions Stratification of patients after acute MI by a simple measure of MI size identifies populations with different long-term prognoses; patients with a QRS score ≥10 (approximately 30% of the left ventricle infarcted) at discharge have poorer outcomes in both the short- and long-term. The standard 12-lead ECG provides a simple, economical means of risk stratification at discharge.