Cardiopulmonary Exercise Testing in Patients with Chronic Heart Failure: Prognostic Comparison from Peak VO2 and VE/VCO2 Slope

BACKGROUND: Cardiopulmonary exercise testing with ventilatory expired gas analysis (CPET) has proven to be a valuable tool for assessing patients with chronic heart failure (CHF). The maximal oxygen uptake (peak V02) is used in risk stratification of patients with CHF. The minute ventilation-carbon dioxide production relationship (VE/VCO2 slope) has recently demonstrated prognostic significance in patients with CHF. METHODS: Between January 2006 and December 2007 we performed CPET in 184 pts (146 M, 38 F, mean age 59.8 +/- 12.9 years), with stable CHF (96 coronary artery disease, 88 dilated cardiomyopathy), in NYHA functional class II (n.107) - III (n.77), with left ventricular ejection fraction (LVEF) /= 35.6 and 25% in those with VE/VCO2 slope 12.2 ml/kg/min (log rank chi2: 50.98, p /= 32.5 and 23% in those with VE/VCO2 slope 12.3 ml/kg/min (log rank chi2: 72.86, p < 0.0001). The VE/VCO2 slope was demonstrated with receiver operating characteristic curve analysis to be equivalent to peak VO2 in predicting cardiac-related mortality (0.89 vs. 0.89). Although area under the receiver operating characteristic curve for the VE/VCO2 slope was greater than peak VO2 in predicting cardiac-related hospitalization (0.88 vs 0.82), the difference was no statistically significant (p = 0.13). CONCLUSION: These results add to the present body of knowledge supporting the use of CPET in CHF patients. The VE/VCO2 slope, as an index of ventilatory response to exercise, is an excellent prognostic parameter and improves the risk stratification of CHF patients. It is easier to obtain than parameters of maximal exercise capacity and is of equivalent prognostic importance than peak VO2.