Original Article
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

https://doi.org/10.4065/77.6.515Get rights and content

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 (92.3% 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.

Section snippets

Initial Development of the Clinical Score

As reported previously,3 the initial (retrospective) study population consisted of 680 consecutive patients with known or suspected CAD who underwent exercise radionuclide angiography between July 10, 1980, and November 25, 1983, and cardiac catheterization within 6 months of the radionuclide angiogram. Patients were excluded from the study if they had previously undergone percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG) or had left bundle branch

Study Population Characteristics

The baseline characteristics of the study group (Table 1) reflect the broad selection criteria. Sex was almost equally balanced. The most common symptom was atypical angina. Few patients had noncardiac chest pain or dyspnea. Hypertension, hypercholesterolemia, and smoking were each present in about half of the patients. Diabetes, insulin use, and a history of previous MI each occurred in 10% or less of the patients.

Prognostic Value of Clinical Score

Among the patients with a normal resting ECG result, there were 29 cardiac

DISCUSSION

The clinical score was developed by using a retrospective analysis population of patients referred for exercise radionuclide angiography to predict the presence of angiographic triple-vessel or left main CAD. It is well documented that the presence of anatomically severe CAD is associated with an adverse prognosis compared with less extensive disease.12, 13, 14, 15 Therefore, the results of this prospective application of the score to predict patient outcomes are not surprising. The clinical

Acknowledgments

We thank Rose M. Busta for preparation of the submitted manuscript.

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    Dr Ho is now with the National University Hospital, Singapore, Republic of Singapore

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