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Spatial R wave amplitude changes during exercise: relation with left ventricular ischemia and function
Insights
Changes in spatial R wave amplitude during exercise testing do not correlate with left ventricular function or indicators of ischemia. This finding suggests spatial R wave amplitude changes are not reliable markers for assessing coronary artery disease severity during exercise.
Area of Science:
- Cardiology
- Exercise Physiology
- Biomedical Engineering
Background:
- Spatial R wave amplitude is a measure derived from electrocardiogram (ECG) signals.
- Its changes during exercise may indicate cardiac issues, but its relationship with left ventricular function and ischemia is not fully understood.
Purpose of the Study:
- To investigate the relationship between spatial R wave amplitude changes during exercise and left ventricular function and ischemic variables in patients with stable coronary artery disease.
Main Methods:
- Compared spatial R wave amplitude changes in patients with increased versus decreased amplitude during exercise.
- Analyzed differences in oxygen consumption, ECG changes (ST depression), left ventricular ejection fraction (LVEF), and thallium-201 ischemia.
- Patients were stratified by maximal heart rate achieved during exercise.
Main Results:
- Significant differences were found only in exercise-induced spatial R wave amplitude changes (p < 0.0001).
- No significant correlation was observed between heart rate changes and spatial R wave amplitude changes.
- Spatial R wave amplitude changes did not correlate with ischemic ECG changes, thallium-201 imaging, or LVEF.
Conclusions:
- Exercise-induced changes in spatial R wave amplitude are not associated with left ventricular function or ischemic changes in patients with stable coronary artery disease.
- Spatial R wave amplitude is not a reliable indicator for assessing ischemia or ventricular function during exercise stress tests.
Abstract:
Thirty patients who exhibited increased and 65 patients decreased spatial R wave amplitude during exercise testing were compared for left ventricular function and ischemic variables. Spatial R wave amplitude was derived from the three-dimensional Frank X, Y, Z leads using computerized methods. All patients had stable coronary artery disease and they were classified into two groups: one that attained a higher (n = 48) and one a lower (n = 47) median value of maximal heart rate during exercise (161 beats/min). Within these two groups, patients with increasing or decreasing spatial R wave amplitude during exercise were analyzed for differences in oxygen consumption, exercise-induced changes in spatial R wave amplitude, ST segment depression laterally (ST60, lead X), ST displacement spatially, left ventricular ejection fraction at rest, change in left ventricular ejection fraction with exercise and thallium-201 ischemia during exercise. Significant differences were demonstrated only in exercise-induced spatial R wave amplitude changes (p less than 0.0001). There was no significant correlation between exercise-induced change in heart rate and change in spatial R wave amplitude in either the group with increasing or the group with decreasing spatial R wave amplitude. It is concluded that changes in spatial R wave amplitude during exercise are not related to ischemic electrocardiographic or thallium-201 imaging changes or to left ventricular ejection fraction determined at rest or during exercise.