Use of a simple clinical score to predict prognosis of patients with normal or mildly abnormal resting electrocardiographic findings undergoing evaluation for coronary artery disease.

Abstract

OBJECTIVE: To determine whether a simple clinical score, which was shown previously to predict the likelihood of severe coronary artery disease (CAD) in patients referred for coronary angiography, could predict prognosis in a separate cohort of patients with normal or mildly abnormal findings on their resting electrocardiogram (ECG) who were undergoing noninvasive evaluation for possible CAD. PATIENTS AND METHODS: The study group included 2255 symptomatic patients with normal (n=1466) or mildly abnormal (nonspecific ST-T-wave abnormalities; n=789) findings on their resting ECG who were referred for exercise thallium testing between 1989 and 1991. Follow-up was 94% complete at a mean +/- SD duration of 6.9+/-1.5 years. The clinical score, which ranged from 0 (lowest risk) to 10 (highest risk), was calculated by awarding 1 point each for male sex, history of myocardial infarction, typical angina, diabetes mellitus, insulin use, and each decade of age older than 40 years. RESULTS: In each ECG group, the clinical score was a significant predictor of cardiac death, nonfatal myocardial infarction, or late revascularization, considered individually or combined, unadjusted or with adjustment for age. Most patients had a score lower than 5; these patients had an excellent 5-year cardiac survival rate (99.7% for the normal ECG findings group and 98.8% for the ST-T-wave abnormalities group). The small subset of patients with a score higher than 5 had a much lower 5-year survival rate (923% for the 8% of patients with normal ECG findings and 86.6% for the 14% of patients with ST-T-wave abnormalities). For patients with a score of 5, the 5-year survival rate was 97.7% for the normal ECG findings group and 95.9% for the ST-T-wave abnormalities group. CONCLUSION: In symptomatic patients with known or suspected CAD and normal or mildly abnormal resting ECG findings, this simple, easily computed clinical score is a useful and valid tool to help determine prognosis.