Coronary Artery Disease
Risk stratification of patients with medically treated unstable angina using exercise echocardiography

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Abstract

Functional testing is recommended for risk stratification of medically treated patients with unstable angina. Exercise echocardiography is used in this situation, but its safety and prognostic value are not well defined. The objective of this study was to assess the incremental prognostic value of exercise echocardiography in 226 consecutive patients (128 men, age 59± 13 years) with medically treated unstable angina, who underwent exercise echocardiography from 1991 to 1996. Clinical risk was designated as low in 108 patients, intermediate in 116, and high in 2 patients according to the unstable angina practice guidelines. There were no major complications from the stress tests. The exercise electrocardiogram was nondiagnostic in 57 patients (25%). Ischemia was identified by exercise electrocardiography in 33 patients and exercise echocardiography in 55 patients. Patients were followed for 29 ± 18 months. After exclusion of 38 patients who underwent early revascularization, 28 patients had cardiac death, nonfatal infarction, and late (>3 months) revascularization. Ischemia at exercise echocardiography was associated with a 24-month event-free survival of 81%, compared to 95% with negative exercise echocardiography (p = 0.02). A positive exercise electrocardiogram was associated with a 24-month event-free survival of 84%, compared to 93% with negative exercise electrocardiograms (p = 0.08). In a Cox regression model, event-free survival was predicted by ischemia at exercise echocardiography (relative risk 2.8, confidence interval: 1.3 to 6.3, p = 0.05), but not at exercise electrocardiography (relative risk 2.1, confidence interval 0.7 to 5.8, p = 0.16).

Section snippets

Patient selection

We prospectively gathered data on 226 consecutive patients with unstable angina who underwent exercise echocardiography between 1991 and 1996 at the Cleveland Clinic Foundation. Unstable angina was defined according to previously established guidelines by the U.S. Department of Health and Human Services: (1) rest angina within 1 week of presentation; (2) new-onset angina of Canadian Cardiovascular Classification class III or IV within 2 months of presentation; and (3) variant angina.9 Higher

Clinical characteristics

Two hundred twenty-six patients (mean age 59 ± 13 years, 128 men) underwent exercise echocardiography for evaluation of unstable angina. One hundred eighty-two patients (80%) were considered to have high or intermediate likelihood of CAD. Although 109 patients (48%) had previous CAD, mean ejection fraction was only mildly reduced to 49 ± 11%. Diabetes mellitus was present in 115 patients (51%), systemic hypertension in 51 patients (23%), cigarette smoking in 113 patients (50%), and

Discussion

In this study, exercise testing was safe for the evaluation of low- to intermediate-risk patients with medically treated unstable angina. Results indicate that exercise echocardiography, but not exercise ECG, is predictive of subsequent events in medically treated patients with unstable angina. These results are independent of the clinical risk profile, although patients at the highest risk (diabetics and patients with known coronary disease) were not additionally risk-stratified by exercise

References (22)

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