Association of baseline newer and established cardiopulmonary exercise test parameters with precapillary pulmonary hypertension severity and survival, a nine year follow-up study

Background Patients with pre-capillary pulmonary hypertension (PH) complain of dyspnea and impaired exercise tolerance due to increased pulmonary vascular resistance (PVR) and mean pulmonary artery pressure (mPAP). Cardiopulmonary Exercise Test (CPET) is recommended at baseline for the evaluation of patients with PH as it may evaluate reasons of dyspnea and exercise intolerance through several cardiac, respiratory and metabolic parameters and give valuable information regarding disease’s burden and patient’s prognosis. We aimed to explore any association between established and newer CPET parameters and right heart catheterization (RHC) parameters, at baseline evaluation, in PH patients after a 9-year follow-up. Methods We studied 31 PH patients [47+14 years, ΒΜΙ=28+5, 19 females, mean pulmonary arterial pressure (mPAP)=47+17 mmHg, pulmonary vascular resistance (PVR)=7.7+4 wood units, 16 with idiopathic pulmonary artery hypertension (IPAH)] diagnosed after a full work-up which included RHC. At baseline evaluation, all patients were subjected to CPET (peak VO2, VE/VCO2 slope, %Workload, circulatory and ventilatory power) using a cycle ergometer and a six-minute walking distance test (6MWD). We defined as primary endpoints the death or lung transplantation or pulmonary endarteriectomy of PH patients during a period of 9+4 years after CPET at baseline evaluation. Results All patients were subjected to CPET uneventfully [peak VO2=12.5+5 ml/min/kg, VE/VCO2 slope=52+17, Workload=49+16%] and 6MWD =474+102meters. Population was divided in Group A [death/surgery, n=17, 48+14 years, 11 females] which reached primary endpoint (12 deaths, 3 lung transplantation, 2 pulmonary endarteriectomy) and Group Β [survivors, n=14, 45+15 years, 8 females). During baseline CPET, Group A patients achieved lower Workload (43+15 vs. 55+15%, p=0.03), peak VO2/kg (10.7+4 vs. 14.8+6ml/min/kg, p=0.02) and Circulatory power (1696+1041 vs. 2407+1080mmHg*ml/min/kg, p=0.05) compared to Group B patients while RHC parameters and 6MWT were similar between groups. Finally, a positive relationship between VE/VCO2 slope and mΡΑP (r=0.38, p=0.03) and PVR (r=0.40, p=0.02) was revealed in the whole population. Conclusions CPET at baseline evaluation, represents a valuable diagnostic tool as its newer (circulatory power) and established (Workload, peak VO2/kg, VE/VCO2) parameters may give useful long-term prognostic information regarding survival of precapillary PH patients.