An increasing number of patients are unable to achieve 85% of their maximum predicted heart rate on exercise testing either due to physical limitations or medications such as beta-blockers. In order to evaluate the reliability of this test at achieved heart rates of less than 85%, exercise 201Tl images and interpretable electrocardiograms of 99 patients with coronary artery disease diagnosed by coronary angiography were reviewed and compared. Tests were considered positive on the basis of 201Tl defects and/or ≥0.1 mV S-T segment depression on electrocardiogram. The patients were divided into three groups according to percent maximum predicted heart rate achieved: group I: 85% or greater; group II: 70-84%, and group III: less than 70%. For these categories, 89, 85 and 86% of the patients, respectively, had one or more segmental 201Tl defects. In contrast, the electrocardiogram was positive in 67, 69 and 60% of the patients. Although 201Tl imaging was more predictive of coronary artery disease than electrocardiogram alone in groups I and II, neither was statistically significant. However, in group III 201Tl imaging was significantly better than the electrocardiogram in predicting disease (86 vs. 60%; p < 0.05). Although there was no significant decrease in the sensitivity of either 201Tl imaging or the electrocardiogram with beta-blocker therapy, for patients taking beta-blockers 201Tl imaging was significantly better than the electrocardiogram alone. It is concluded that patients unlikely to achieve adequate chronotropic response with exercise may be more reliably evaluated with exercise 201Tl imaging than with electrocardiography alone.
|Original language||English (US)|
|Number of pages||7|
|Journal||American Journal of Noninvasive Cardiology|
|State||Published - Jan 1 1991|
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine