ECG findings associated with increased mortality risk include anterior STE, distortion of the terminal portion of the QRS complex (Fig. 3), left bundle-branch block, right bundle-branch block, advanced atrioventricular block, and atrial fibrillation
(9,11,21,40). In GUSTO-1, the 30-d mortality rate was 9.9 vs 5.0% in patients with anterior vs inferior STE. The relative risk of death, reinfarction, or congestive heart failure was 4-fold greater in patients with inferior infarction if ST-segment depression was also noted in the anterior lead group, particularly leads V4-V6 or if evidence of right ventricular involvement was present (41-45). In GUSTO-1, the 30-d mortality rates were 18.7, 17, 14, and 17% for patients with left bundle-branch block, right bundle-branch block, left anterior fascicular block, and left posterior fascicular block, respectively, compared with 6% in patients with a normal conduction pattern (46).
Early resolution of STE (within hours of thrombolysis) is associated with a more favorable prognosis than in patients with persistent STE. Additional STE over and above the initial elevation seen in the first h of thrombolysis with ultimate resolution is also associated with favorable clinical outcome (47) (Fig. 3E). The 30- and 180-d mortality rates of patients who had >50% resolution of STE within 4 h of treatment were 3.5 and 5.7% compared to 5.7 and 7.4% in patients without these findings in the Gruppo Italiano per lo Studio della Sopravvienza nell'Infarto Miocardico (GISSI)-2 (48). The International Joint Efficacy Comparison of Thrombolytics (INJECT) study, which compared the effects of reteplase or streptokinase in 6010 patients reported a 35-d mortality rate of 2.5% in patients with complete resolution of STE compared with 17.5% in patients without ST-segment resolution (49) (Fig. 4).
LV function can be estimated from the resting ECG at the time of hospital discharge. Silver et al. (50) reported a positive predictive value of 98% to estimate LV ejection fraction >40% in patients with new non-anterior Q wave infarction, no previous history of Q wave MI, or congestive heart failure. The findings were validated in 10,756 patients enrolled in GUSTO-1 (51).
New Q waves as compared to absence of new Q waves at the time of presentation to the emergency room are also associated with higher cardiac mortality rates at 30 d (7 vs 2%) and at 5 yr (16 vs 6%) (52).
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