Abstract
PURPOSE:: A significant discrepancy between measured oxygen consumption (VO2) (via ventilatory expired gas analysis) and estimated VO2 (via the imposed workload) frequently is reported in the heart failure (HF) population during symptom-limited exercise testing. The purpose of this investigation was to examine the difference between measured and estimated VO2 (VO2 discrepancy) during a highly conservative ramping protocol.
METHODS:: For this study, 28 subjects with compensated HF (20 men and 8 women; age, 51.1 +/- 14.6 years) and 19 healthy control subjects (age-, gender-, and activity-matched to an HF subgroup) underwent symptom-limited exercise testing (treadmill) with ventilatory expired gas analysis.
RESULTS:: Peak estimated and measured VO2 values were significantly higher in the age-, gender-, and activity-matched control group than in the HF group, but the change in measured VO2 per change in estimated VO2 ([DELTA]measured/[DELTA]estimated VO2 slope) and the VO2 discrepancy did not reach statistical significance. Peak estimated VO2 was a significant predictor of peak measured VO2 in the overall HF group (R2 = 0.90; P < .001).
CONCLUSIONS: Although estimated VO2 is not considered a replacement for measured VO2, these results indicate that a highly conservative exercise protocol may allow for a more accurate prediction of peak measured VO2 via the estimated oxygen cost for a given workload in patients with compensated HF.