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Treadmill exercise testing in the presence of digitals therapy or nonspecific ST-T changes: correlation with coronary
Insights
Digitalis therapy can affect treadmill exercise test results in patients with chest pain. Stricter criteria improve the accuracy of treadmill tests for diagnosing coronary artery disease in these individuals.
Area of Science:
- Cardiology
- Exercise Physiology
Background:
- Treadmill exercise testing is a common diagnostic tool for coronary artery disease (CAD).
- Digitalis therapy and nonspecific ST-T changes on resting electrocardiograms can potentially alter exercise test interpretations.
- Accurate interpretation is crucial for timely diagnosis and management of CAD.
Purpose of the Study:
- To evaluate the impact of digitalis therapy on the diagnostic accuracy of the treadmill exercise test.
- To assess the specificity and sensitivity of the treadmill test in patients with and without digitalis treatment.
- To determine if modified interpretation criteria can improve test performance in patients on digitalis.
Main Methods:
- Retrospective analysis of 93 patients with chest pain undergoing treadmill exercise tests and coronary angiography.
- Patients were stratified based on digitalis use and presence/absence of coronary artery disease.
- Standard criteria (≥1.0 mm ST depression) and more stringent criteria (≥1.5 mm ST depression) were used for treadmill test interpretation.
Main Results:
- The treadmill test showed lower specificity (73%) in patients on digitalis compared to those not on digitalis (96%).
- Sensitivity was 63% for patients on digitalis and 71% for those not on digitalis.
- Applying more stringent criteria (≥1.5 mm ST depression) significantly improved specificity in patients on digitalis to 93%, while maintaining good diagnostic value for CAD.
Conclusions:
- Digitalis therapy significantly impacts the specificity of the standard treadmill exercise test.
- More stringent criteria for ST depression (≥1.5 mm) enhance the accuracy of the treadmill test in patients receiving digitalis.
- Modified interpretation criteria are recommended for treadmill exercise testing in patients on digitalis therapy to improve diagnostic reliability for coronary artery disease.
Abstract:
Treadmill exercise test results were studied in 93 patients with chest pain who had received digitalis therapy or had nonspecific ST-T changes in the resting electrocardiogram. Results of the treadmill test were correlated with the findings of coronary angiography. A positive treadmill result was defined as horizontal or down-sloping ST segment depression greater than or equal to 1.0 mm. Of the 40 patients with no or insignificant coronary artery disease, 15 had taken digitalis; 4 of the 15 demonstrated a positive response on the treadmill test. Of the 53 patients with coronary artery disease, 21 had taken digitalis; 15 of the 21 displayed a positive response. Among the remaining 32 not on digitalis, 20 had a positive response. The specificity of the treadmill exercise test was 96% in patients with coronary artery disease not on digitalis and whose resting electrocardiogram showed nonspecific ST changes. The specificity of the treadmill test in patients who had received digitalis was 73%. Sensitivity was 63% and 71%, respectively. By utilizing more stringent criteria in the interpretation of the treadmill exercise test (greater than or equal to 1.5 mm ST depression), among the patients on digitalis only 6.7% (1/15) with normal coronary arteries and 48% (10/21) with coronary artery disease had a positive response. With the use of the latter criterion the test was specific in 93% (14/15) of the patients and is usually indicative of coronary artery disease.