Key result
Patients with significant coronary artery disease exhibited significantly prolonged oxygen uptake recovery half-times (78.1 vs 55.7 seconds) and decreased ∆VO2/∆WR ratios above the anaerobic threshold compared to those without significant stenosis.
Why the study?
Do exercise and recovery VO2 kinetics differentiate between true positive and false positive exercise ECGs for coronary artery disease?
Observational (n=37)
No
Do exercise and recovery VO2 kinetics differentiate between true positive and false positive exercise ECGs for coronary artery disease?
Absolute Event Rate: 78.1% vs 55.7%
p-value: p=0.006
Measurement of exercise and recovery VO2 kinetics during cardiopulmonary exercise testing improves the diagnostic accuracy of exercise ECG for coronary artery disease.
May differentiate true- from false-positive exercise ECGs for CAD; leaves open prospective validation before diagnostic integration.
BACKGROUND: The aim of the current study was to determine if the slowed exercise oxygen uptake (VO(2)) kinetics, which is developed by myocardial ischemia, would be accompanied by delayed recovery VO(2) kinetics in patients with coronary artery disease (CAD). METHODS AND RESULTS: Thirty-seven patients with significant ST depression during treadmill exercise underwent cardiopulmonary exercise testing with cycle ergometer. Measurements performed are the ratios of change in increase in oxygen (O(2)) uptake relative to increase in work rate (DeltaVO(2)/DeltaWR) across anaerobic threshold (AT) and 1 mm ST depression point (ST-dep), the time constants of VO(2) during recovery (T(1/2) VO(2)), stress radio-isotope scintigraphy and coronary angiography. Patients were divided into CAD positive (CAD+) and CAD negative (CAD-) groups, based on coronary angiography. In CAD+, DeltaVO(2)/DeltaWR decreased above AT and ST-dep, in contrast to CAD- patients. The T(1/2) VO(2) in CAD+ (103.1 +/-13.0 s) was greater than that of CAD- (76.5 +/-8.7 s) and showed negative correlations to the ratios of DeltaVO(2)/DeltaWR across AT and ST-dep. These parameters improved in the patients who underwent coronary bypass surgery. CONCLUSIONS: Exercise and recovery VO(2) kinetics were slowed when myocardial ischemia was provoked by exercise. Measurement of exercise and recovery VO(2) kinetics improve the accuracy of the exercise electrocardiogram diagnosis of CAD.
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Tajima et al. (2009) conducted an observational in Suspected coronary artery disease with exercise-induced ST depression (n=37). Significant coronary artery stenosis (CAD+) vs. No significant coronary artery stenosis (CAD-) was evaluated on Half time of recovery of oxygen uptake (T1/2 VO2) in seconds (p=0.006). Patients with significant coronary artery disease exhibited significantly prolonged oxygen uptake recovery half-times (78.1 vs 55.7 seconds) and decreased ∆VO2/∆WR ratios above the anaerobic threshold compared to those without significant stenosis.
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