Clinical and Hemodynamic Correlates and Prognostic Value of VE/VCO2 Slope in Patients With Heart Failure With Preserved Ejection Fraction and Pulmonary Hypertension

Abstract

Background: Impaired exercise capacity is one of the hallmarks of heart failure with preserved ejection fraction (HFpEF), but the clinical and hemodynamic correlates and prognostic value of exercise testing in patients with HFpEF is unknown.

Methods: Patients with HFpEF (left ventricular ejection fraction [LVEF] ≥45%) and pulmonary hypertension underwent cardiopulmonary exercise test (CPX) to measure maximal (peak VO₂) and submaximal (ventilatory equivalent for carbon dioxide [VE/VCO₂] slope) exercise capacity. In addition, right heart catheterization was performed. Patients were grouped in tertiles based on the VE/VCO₂ slope. Univariate and multivariate regression analyses were performed. A Cox regression analysis was performed to determine the mortality during follow-up.

Results: We studied 88 patients: mean age 73 ± 9 years, 67% female, mean LVEF 58%, median N-terminal pro-B-type natriuretic peptide (NT-proBNP) 840 (interquartile range 411-1938) ng/L. Patients in the highest VE/VCO₂ tertile had the most severe HF, as reflected in higher New York Heart Association functional class and higher NT-proBNP plasma levels (all P < .05 for trend), whereas LVEF was similar between the groups. Multivariable regression analysis with backward elimination on invasive hemodynamic measurements showed that VE/VCO₂ slope was independently associated with pulmonary vascular resistance (PVR). Cox regression analysis showed that increased VE/VCO₂ slope (but not peak VO₂) was independently associated with increased mortality.

Conclusion: Increased VE/VCO₂ slope was associated with more severe disease and higher PVR and was independently associated with increased mortality in patients with HFpEF.

Keywords: VE/VCO(2) slope; cardiopulmonary exercise test; heart failure with preserved ejection fraction.