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Background: Minute ventilation/CO(2) production (VE/Vco(2)) slope is an index determined by cardiopulmonary exercise testing, which incorporates pertinent cardiac, pulmonary, and skeletal muscle physiology into a substantive composite assessment. The VE/Vco(2) slope has many applications, including utility as a well-validated prognostic gauge for patients with heart failure (HF). In this study, we combine VE/Vco(2) slope with systolic blood pressure, creating a novel index that we labeled ventilatory power. Ventilatory power links the combined physiology inherent in the VE/Vco(2) slope to peripheral pressure, adding an additional dimension pertinent to HF assessment. Whereas the related concept of circulatory power links peak oxygen consumption with peak systolic blood pressure as a prognostic index, we hypothesized that ventilatory power would provide greater prognostic discrimination than VE/Vco2 slope, peak oxygen consumption, and circulatory power for patients with systolic HF., Methods and Results: Patients with systolic HF (left ventricular ejection fraction ≤35%) underwent symptom-limited cardiopulmonary exercise testing as part of routine management and were followed for up to 4 years for major cardiac events (mortality, left ventricular assist device implantation, and heart transplantation). Eight hundred seventy-five patients with HF (left ventricular ejection fraction, 26±9%; mean age, 55±14) were studied. Cardiopulmonary exercise testing indices peak oxygen consumption, VE/Vco(2) slope, circulatory power, and ventilatory power were all predictive of cardiac events (P<0.001). Multivariate analysis demonstrated that ventilatory power was the strongest indicator of prognosis., Conclusions: Although circulatory power and traditional cardiopulmonary exercise testing parameters can be used to predict prognosis among patients with HF, ventilatory power provides relatively greater prognostic discrimination and may constitute a relatively more useful composite tool.

Several investigations have demonstrated that higher body weight, as assessed by the body mass index, is associated with improved prognosis in patients with heart failure (HF). The purpose of the present investigation was to assess the influence of HF etiology on the prognostic ability of the body mass index in a cohort undergoing cardiopulmonary exercise testing. A total of 1,160 subjects were included in the analysis. All subjects underwent cardiopulmonary exercise testing, at which the minute ventilation/carbon dioxide production slope and peak oxygen consumption were determined. In the overall group, 193 cardiac deaths occurred during a mean follow-up of 30.7 +/- 25.6 months (annual event rate 6.0%). The subjects classified as obese consistently had improved survival compared to those classified as normal weight (overall survival rate 88.0% vs or=43.4, p <0.001) for both etiologies, and the body mass index added prognostic value (residual chi-square >or=4.7, p <0.05). In conclusion, these results further support the notion that obesity confers improved prognosis in patients with HF, irrespective of the HF etiology. Moreover, the body mass index appears to add predictive value during the cardiopulmonary exercise testing assessment. However, survival appears to differ according to HF etiology in subjects classified as overweight.

Background: Ventilatory efficiency, commonly assessed by the minute ventilation (VE)-carbon dioxide production (VCO2) slope, is a powerful prognostic marker in the heart failure population. The purpose of the present study is to refine the prognostic power of the VE/VCO2 slope by developing a ventilatory class system that correlates VE/VCO2 cut points to cardiac-related events., Methods and Results: Four hundred forty-eight subjects diagnosed with heart failure were included in this analysis. The VE/VCO2 slope was determined via cardiopulmonary exercise testing. Subjects were tracked for major cardiac events (mortality, transplantation, or left ventricular assist device implantation) for 2 years after cardiopulmonary exercise testing. There were 81 cardiac-related events (64 deaths, 10 heart transplants, and 7 left ventricular assist device implantations) during the 2-year tracking period. Receiver operating characteristic curve analysis revealed the overall VE/VCO2 slope classification scheme was significant (area under the curve: 0.78 [95% CI, 0.73 to 0.83], P<0.001). On the basis of test sensitivity and specificity, the following ventilatory class system was developed: (1) ventilatory class (VC) I: < or = 29; (2) VC II: 30.0 to 35.9; (3) VC III: 36.0 to 44.9; and (4) VC IV: > or = 45.0. The numbers of subjects in VCs I through IV were 144, 149, 112, and 43, respectively. Kaplan-Meier analysis revealed event-free survival for subjects in VC I, II, III, and IV was 97.2%, 85.2%, 72.3%, and 44.2%, respectively (log-rank 86.8; P<0.001)., Conclusions: A multiple-level classificatory system based on exercise VE/VCO2 slope stratifies the burden of risk for the entire spectrum of heart failure severity. Application of this classification is therefore proposed to improve clinical decision making in heart failure.