Background-An abnormal signal-averaged ECG (SAECG) is a noninvasive marker of the substrate of sustained ventricular tachycardia after myocardial infarction. We assessed its prognostic ability in patients with asymptomatic unsustained ventricular tachycardia, coronary artery disease, and left ventricular dysfunction. Methods and Results-A blinded core laboratory analyzed SAECG tracings from 1925 patients in a multicenter trial. Cox proportional hazards modeling was used to examine individual and joint relations between SAECG variables and arrhythmic death or cardiac arrest (primary end point), cardiac death, and total mortality. We also assessed the prognostic utility of SAECG at different levels of ejection fraction (EF). A filtered QRS duration Ͼ114 ms (abnormal SAECG) independently predicted the primary end point and cardiac death, independent of clinical variables, cardioverter-defibrillator implantation, and antiarrhythmic drug therapy. With an abnormal SAECG, the 5-year rates of the primary end point (28% versus 17%, Pϭ0.0001), cardiac death (37% versus 25%, Pϭ0.0001), and total mortality (43% versus 35%, Pϭ0.0001) were significantly higher. The combination of EF Ͻ30% and abnormal SAECG identified a particularly high-risk subset that constituted 21% of the total population. Thirty-six percent and 44% of patients with this combination succumbed to arrhythmic and cardiac death, respectively. Conclusions-SAECG is a powerful predictor of poor outcomes in this population. The noninvasive combination of an abnormal SAECG and reduced EF may have utility in selecting high-risk patients for intervention.

for the GUSTO-I InvestigatorsBackground-When a patient survives thrombolysis for acute myocardial infarction, little information from large studies exists from which to estimate prognosis during follow-up visits. Methods and Results-Baseline, in-hospital, and later survival data were collected from 41 021 patients enrolled in Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries, a randomized trial of 4 thrombolytic-heparin regimens with standard aspirin and ␤-blockade. Cox proportional hazards models were developed to predict 1-year survival in 30-day survivors (nϭ37 869) from baseline clinical and ECG factors and in-hospital factors; a combined model then was developed (C-index 0.800). The model was simplified into a nomogram to predict individual outcomes (C-index 0.754). Factors reflecting demographics (advanced age, lighter weight), larger infarctions (higher Killip class, lower blood pressure, faster heart rate, longer QRS duration), cardiac risk (smoking, hypertension, prior cerebrovascular disease), and arrhythmia were important predictors of death between 30 days and 1 year. Black race was associated with a substantial increase in risk after considering other factors. Revascularization was associated with reduced risk between 30 days and 1 year. Conclusions-When evaluating a patient who has survived acute infarction treated with thrombolysis, clinicians can estimate the likelihood of survival from factors easily measured during admission. Although many risk factors clearly relate to age, left ventricular dysfunction, or clinical instability, black race is an unexplained risk factor requiring further examination.