Peak oxygen consumption, NT-proBNP and echocardiographic changes in patients with chronic heart failure

Abstract

To assess peak oxygen consumption (peak VO₂) derived from cardiopulmonary exercise testing (CPET), concentrations of NT-proBNP and echocardiographic changes in patients with chronic heart failure (CHF) and reduced left ventricular ejection fraction (LVEF, <40%). Seventy patients were included and divided into two groups according to the New York Heart Association (NYHA) classification: NYHA II group (17 cases) and NYHA III-IV group (53 cases). The basic clinical information, plasma concentration of NT-proBNP at rest, echocardiographic parameters and peak VO₂from CPET were compared between two groups. Correlation among peak VO₂, NT-proBNP and echocardiographic parameters in this patient cohort was assessed and their abilities to discriminate the NYHA III-IV grade were analyzed through c-Statistic. Left atrial diameter ((51.3 ± 7.2) mm vs. (44.0±7.4) mm, P<0.001) was larger, plasma concentration of NT-proBNP (1 379-4 399 pmol/L vs. 1 109-2 356 pmol/L, P<0.01) was higher and peak VO₂((13.4 ± 3.5) ml·kg⁻¹·min⁻¹ vs. (18.2 ± 3.7) ml·kg⁻¹·min⁻¹, P<0.001) were significantly lower in NYHA III-IV group than those in NYHA II group. However, left ventricular end-diastolic diameter (LVEDD) and LVEF were similar between two groups. Peak VO₂correlated significantly with NT-proBNP (r=-0.311, P<0.01), but neither peak VO₂nor NT-proBNP correlated with echocardiographic parameters (LA, LVEDD and LVEF). ROC analysis showed that peak VO₂had the strongest discriminatory power for detecting NYHA III-IV grade patients (AUC=0.835, P<0.001), followed by the NT-proBNP (AUC=0.723, P<0.01). Peak VO₂is a more sensitive parameter to detect the disease aggravation (NYHA III-IV grade) of the CHF patients with reduced LVEF compared to plasma NT-proBNP and echocardiographic parameters (LA, LVEDD, LVEF).