Related Experiment Videos
Analysis of exercise-induced R-wave-amplitude changes in detection of coronary artery disease in patients with
Insights
Exercise electrocardiogram (ECG) is a poor indicator for coronary artery disease (CAD) in patients taking digitalis. R-wave variations showed fewer false positives than ST-segment depression but had 50% false negatives.
Area of Science:
- Cardiology
- Diagnostic Imaging
- Exercise Physiology
Background:
- Exercise electrocardiography (ECG) is a common non-invasive test for diagnosing coronary artery disease (CAD).
- The accuracy of exercise ECG can be affected by various factors, including medication.
- Digitalis is frequently prescribed for cardiac conditions and may influence ECG interpretations.
Purpose of the Study:
- To compare the diagnostic accuracy of exercise ECG parameters against gold-standard tests for CAD.
- To evaluate the impact of digitalis treatment on the sensitivity and specificity of exercise ECG.
- To determine the reliability of ST-segment depression and R-wave variations in diagnosing CAD in patients on digitalis.
Main Methods:
- Seventy male patients with chest pain complaints underwent exercise ECG, stress thallium-201 scanning, and coronary arteriography.
- Patients were divided into two groups: those not receiving treatment (Group I) and those receiving digitalis (Group II).
- Exercise ECG criteria included ST-segment depression (≥1.5 mm) and R-wave amplitude modifications.
Main Results:
- In Group I (no digitalis), ST-segment depression showed high sensitivity (92%) and specificity (82%). R-wave variations had lower sensitivity (41%) and specificity (74%).
- In Group II (digitalis), ST-segment depression had 100% sensitivity but only 33% specificity. R-wave variations showed 50% sensitivity and 70% specificity.
- R-wave variations yielded fewer false positives than ST-segment depression in digitalis-treated patients, but with a significant 50% false negative rate.
Conclusions:
- Exercise ECG, particularly R-wave variation, is a less reliable indicator of CAD in patients treated with digitalis.
- ST-segment depression is highly sensitive but poorly specific in this population, leading to potential overdiagnosis.
- Coronary artery disease diagnosis in patients on digitalis may require alternative or adjunctive diagnostic strategies.
Abstract:
Specificity and sensitivity of exercise ECG were compared to exercise stress thallium 201 scanning and coronary arteriograms in 70 male patients with typical or atypical chest pain complaints, without previous myocardial infarction. 50 patients (group I) did not receive any treatment; 20 patients (group II) received digitalis as preventive treatment of atrial arrhythmias or for no particular reason. Only subjects with concordant results in radionuclide and angiography examinations were considered as coronary artery disease patients. Exercise stress tests were performed sitting on the bicycle ergometer using a progressive loading profile (30 W for 3 min), to the symptom-limited capacity (VO2SL). Positive exercise ECG were confirmed on ST decrease (1.5 mm) or on absence or increase in R-wave-amplitude modifications (V5). In the group I patients, ECG-ST-modification sensitivity, specificity, predictive value (+) and efficiency were, respectively, 92, 82, 86 and 88%. R-wave-variation sensitivity, specificity, predictive value (+) and efficiency were, respectively, 41, 74, 65 and 56%. In the group II patients, ST-depression sensitivity, specificity, predictive value (+) and efficiency were, respectively, 100, 33, 59 and 65%. R-wave-variation sensitivity, specificity, predictive value (+) and efficiency were, respectively, 50, 70, 63 and 60%. It was concluded that R-wave-amplitude variations induced lower false positive responses than ST-segment depression in patients under digitalis treatment. False negative responses were unfortunately 50% using the R-wave criterion. Exercise ECG was finally judged as a poor indicator of CAD in patients under digitalis treatment.