Relation of the prognostic value of ventilatory efficiency to body mass index in patients with heart failure

The ventilatory efficiency, minute ventilation (VE)/carbon dioxide production (VCO2), slope consistently provides valuable prognostic information in patients with heart failure (HF). Patients with a higher body mass index (BMI) have demonstrated an improved prognosis in the HF population, a phenomenon that has been termed the "obesity paradox." The purpose of this study was to evaluate the prognostic ability of the VE/VCO2 slope according to BMI in patients with HF. Seven-hundred four patients with HF (555 men, 149 women, mean age 56.8 +/- 13.4 years, ejection fraction 33.1 +/- 13.3%) with a BMI >= 18.5 kg/m(2) underwent cardiopulmonary exercise testing. Subjects were divided into 3 BMI subgroups (18.5 to 24.9, 25.0 to 29.9, and >= 30 kg/m(2)). Each subject was tracked for major cardiac events (death, transplantation, left ventricular assist device implantation) for 2 years after testing. There were 86 major cardiac events (71 deaths, 10 transplantations, 5 left ventricular assist device implantations) during the 2-year tracking period (overall annual event rate 8.2%). The VE/VCO2 Slope was the strongest prognostic marker in each BMI subgroup. Subjects in the highest BMI group had the lowest mean VENCO2 slope and the lowest rate of major cardiac events of the 3 groups. Multivariate Cox regression analysis showed that peak VO2 did not add additional prognostic value to the VE/VCO2 slope and was removed from the regression for each BMI subgroup. In conclusion, the findings of the present study indicate that VE/VCO2 slope maintains prognostic value irrespective of BMI in patients with HF. (c) 2008 Elsevier Inc. All rights reserved.