Combining the ventilatory response to exercise and peak oxygen consumption is no better than peak oxygen consumption alone in predicting mortality in chronic heart failure

Background: A low peak oxygen uptake (pV(O2)) and steep V-E/V-CO2 slope are independently associated with a worse prognosis in patients with chronic heart failure (CHF). We wished to confirm whether combining these variables as a ratio would lead to a more accurate predictor of prognosis than using either alone. Methods: 388 CHF patients completed a treadmill-based cardiopulmonary exercise test (CPET) to volitional exhaustion using a modified Bruce protocol. Results: 212 CHF patients completed the CPET with a peak RER >= 1.0. Of these, 48 patients died and one was transplanted during follow-up. In surviving patients, the median follow-up period was 42 months (IQR 34-49 months). The ratio V-E/V-CO2 slope/pV(O2) was calculated for each individual and its ability to predict outcome compared with other variables. The Cox multivariable survival analysis showed that pV(O2) was the strongest independent predictor of mortality in CHF patients. Conclusion: Our study shows that the composite variable V-E/V-CO2 slope/pV(O2) is a less effective prognosticator than pVo2 alone in patients with CHF. (c) 2007 European Society of Cardiology. Published by Elsevier B.V. All rights reserved