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True sensitivity of cardiac exercise testing. A combined clinical evaluation of multiple parameters
Insights
Combining exercise test parameters significantly improves the detection of coronary artery disease. Work capacity, ST depression, and angina are key indicators, enhancing diagnostic sensitivity in patients with suspected heart conditions.
Area of Science:
- Cardiology
- Exercise Physiology
Background:
- Coronary artery disease (CAD) diagnosis relies on various clinical and physiological parameters.
- Maximal exercise testing is a common diagnostic tool, but its sensitivity and specificity can vary.
Purpose of the Study:
- To evaluate the sensitivity of individual and combined parameters from maximal exercise tests for detecting coronary artery disease.
- To assess the diagnostic accuracy of exercise testing in patients with and without obstructive coronary disease.
Main Methods:
- Maximal exercise tests were conducted on 308 patients with angiographically confirmed CAD, 38 patients with non-obstructive coronary vessels, and 236 healthy volunteers.
- Sensitivity of parameters like ST segment depression, test-induced angina, and work capacity restriction was analyzed individually and in combination.
- Exercise responses were assessed using bicycle ergometry and treadmill protocols.
Main Results:
- Individual parameters showed moderate sensitivity: work capacity restriction (65%), ST segment depression (56%), and test angina (55%).
- Combining parameters progressively increased sensitivity in the CAD group, reaching 87% with the inclusion of heart rate/blood pressure responses and arrhythmias.
- False positive rates were observed in non-obstructed coronary vessel patients (54%) and healthy subjects (15%), with R wave amplitude change excluded due to high false positivity (24%).
Conclusions:
- A sequential combination of exercise test parameters significantly enhances diagnostic sensitivity for coronary artery disease.
- Careful interpretation is needed due to potential false positives in non-CAD populations, highlighting the importance of multiple indicators.
Abstract:
Maximal exercise tests were performed in 308 patients with angiographically defined coronary disease, in 38 patients whose coronary vessels were not obstructed, and in 236 clinically normal volunteers. The sensitivity of parameters indicating ischaemia was evaluated singly and in combination in each group. The most sensitive individual parameters were work capacity restriction (65%), ST segment depression (56%) and test angina (55%). When the sequence of parameters were assessed successively in the coronary group, the sensitivity rose from 56% with ST depression to 70% with the addition of test angina, to 85% when work capacity restriction was added, and to 87% when inadequate heart rate or blood pressure responses or repetitive ventricular arrhythmias were included. In the group of patients whose coronary vessels were not obstructed, substantial clinical abnormalities and a bias to carry out angiography in those with abnormal exercise responses led to false ST segment changes in 34%, and, in a further 20%, to positivity in the other parameters. In clinically normal subjects a 15% "false" positive rate occurred. One parameter (R wave amplitude change) was falsely positive in 24%, and was therefore excluded. Grouped parameter sensitivity for patients who exercised on a bicycle and those who used a treadmill was similar.