The predictive value of minute ventilation versus carbon dioxide production in pulmonary hypertension associated with left heart disease

BACKGROUND: The aim of the present study was to investigate the role of key cardiopulmonary exercise testing (CPET) parameters in the identification of pre-capillary components in patients with pulmonary hypertension associated with left heart disease (PH-LHD), and to evaluate their correlations with hemodynamic parameters. METHODS: Ninety patients with PH-LHD underwent right-heart catheterization, echocardiography, and CPET. The differences in related indexes between a combined post- and pre-capillary PH (Cpc-PH) group (n=47) and an isolated post-capillary PH (Ipc-PH) group (n=43) were compared. Correlation analysis was performed. Logistic regression and receiver operator characteristic (ROC) analyses were performed to assess the ability of CPET variables to distinguish patients with Cpc-PH from those with Ipc-PH. RESULTS: The hemodynamics, hyperventilation and right ventricular function of Cpc-pH group were worse than those of Ipc-pH group. The parameters related to minute ventilation versus carbon dioxide production (VE/VCO(2)) played a significant role in the differentiation of Cpc-PH and Ipc-PH, and had a moderate positive correlation with pulmonary vascular resistance (PVR). Univariate and multivariate logistic analyses showed that lowest percentage of VE/VCO(2) in predicted value (VE/VCO(2)%pred) was the single best predictor of Cpc-PH, and the area under ROC curve also confirmed that lowest VE/VCO(2)%pred (≥137%) could serve as a novel diagnostic marker for Cpc-PH. On the basis of this lowest VE/VCO(2)%pred threshold, patients were divided into two groups. Most hemodynamic parameters were worse in patients with a lowest VE/VCO(2)%pred ≥137%. CONCLUSIONS: VE/VCO(2)-related parameters are powerful prognosticators for the presence of pre-capillary components in patients with PH-LHD, especially lowest VE/VCO(2)%pred.