Oxygen consumption and carbon-dioxide recovery kinetics in the prediction of coronary artery disease severity and outcome.

Popovic D, Martic D, Djordjevic T, Pesic V, Guazzi M, Myers J,
Mohebi R, Arena R

Int J Cardiol. 2017 Dec 1;248:39-45. doi: 10.1016/j.ijcard.2017.06.107. Epub 2017
Jun 28.

BACKGROUND: Revascularization appears to be beneficial only in patients with high
levels of ischemia. This study examined the utility of gas analysis during the
recovery phase of cardiopulmonary exercise testing (CPET) in predicting coronary
artery disease (CAD) severity and prognosis.
METHODS: 40 Caucasian patients (21.2% females), mean age 63.5±7.6 with
significant coronary artery lesions (≥50%) were studied. Within two months of
coronary angiography, CPET on a treadmill (TM) and recumbent ergometer (RE) were
performed on two visits 2-4days apart; subjects were subsequently followed
32±10months. Myocardial wall motion was recorded by echocardiography at rest and
peak exercise. Ischemia was quantified by the wall motion score index (WMSI).
RESULTS: Mean ejection fraction was 56.7±9.6%. Patients with 1-2 stenotic
coronary arteries (SCA) showed a poorer CPET response during the recovery phase
than patients with 3-SCA. ROC analysis revealed the change of carbon-dioxide
output (∆VCO2) recovery/peak (area under ROC curve 0.77, p=0.02, Sn=87.5%,
Sp=70.4%) and oxygen uptake (∆VO2) recovery/peak during TM CPET (area under ROC
curve 0.76, p=0.03, Sn 75.0%, Sp 77.8%) were significant in distinguishing
between 1-2-SCA and 3-SCA. The same variables predicted ΔWMSI peak/rest on
univariate analysis (p<0.05). Multivariate Cox analysis revealed a high
predictive value of ∆VO2 recovery/peak obtained during TM CPET for composite
endpoint of cumulative cardiac events (HR=1.27, CI=1.07-1.51, p=0.008).
CONCLUSIONS: The current study suggests CPET parameters in recovery hold
predictive value for CAD severity and prognosis. TM testing seems to be a better
approach in the assessment of CAD severity and prognosis.