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Pathophysiologic factors governing the variability of ischemic responses to treadmill and bicycle exercise
1Division of Cardiology, Cedars-Sinai Medical Center, Los Angeles, Calif.
Insights
Serial testing for coronary artery disease (CAD) shows varied ischemic responses. Variability is linked to disease severity and left ventricular ejection fraction (LVEF) changes during exercise, impacting diagnosis.
Area of Science:
- Cardiology
- Exercise Physiology
Background:
- Ischemic responses in coronary artery disease (CAD) patients can vary significantly during serial testing.
- The underlying pathophysiological mechanisms driving this variability are not well understood.
Purpose of the Study:
- To investigate clinical, hemodynamic, physiological, and anatomical factors influencing variability in ischemic responses.
- To compare exercise electrocardiography responses between bicycle and treadmill tests in CAD patients.
Main Methods:
- Evaluated 140 patients (77 with CAD, 21 normal, 42 low CAD likelihood).
- Utilized bicycle and treadmill exercise electrocardiography.
- Obtained radionuclide ventriculography during bicycle exercise.
Main Results:
- Bicycle exercise induced higher systolic blood pressure and double-product responses compared to treadmill.
- Variability in ischemic responses was frequent, with 39% of CAD patients showing ST-segment depression on only one test.
- Ischemic variability decreased as left ventricular ejection fraction (LVEF) response to exercise worsened.
Conclusions:
- Variability in ischemic responses during serial exercise testing in CAD is common.
- This variability is significantly associated with the extent of coronary artery disease and impaired left ventricular function.
- Understanding this variability is crucial for accurate diagnosis and management of CAD.
Abstract:
Ischemic responses may vary considerably when patients with coronary artery disease (CAD) are tested serially, but the pathophysiologic mechanisms that govern this variability have not been well evaluated. We thus evaluated whether clinical, hemodynamic, physiologic, and anatomic factors influenced the variability in ischemic responses among 140 patients (mean age 54 +/- 11 years) subjected to both bicycle and treadmill exercise electrocardiography. Radionuclide ventriculography was obtained during bicycle exercise in each patient. The population included 77 patients with CAD, 21 patients with normal coronary arteriograms, and 42 patients with < 5% likelihood of CAD. Bicycle exercise evoked higher systolic blood pressure (p < 0.001) and double-product (p < 0.001) responses compared with treadmill exercise in the patients with CAD and in the normal subjects, and it evoked a lower frequency of chest pain (12% vs 41%, p < 0.001) in the 34 patients with CAD who had ST-segment depression during both exercise tests. There was a high frequency of variability in ischemic responses during treadmill versus bicycle exercise: 22 (39%) of the 56 CAD patients who had exercise-induced ST-segment depression manifested this response during one stress test only. This variability was strongly related to the functional and anatomic magnitude of disease. Ischemic variability decreased progressively as the response of left ventricular ejection fraction (LVEF) to exercise worsened progressively (p = 0.003 by analysis of variance), from 83% in those with an LVEF increase of > 10% with exercise to only 13% in those with an LVEF fall of > or = 5% with exercise.(ABSTRACT TRUNCATED AT 250 WORDS)