Clinical utility of ventilatory and gas exchange evaluation during low‐intensity exercise for risk stratification and prognostication in pulmonary arterial hypertension

Exercise capacity correlates with PAH severity and prognosis. However, exercise contraindications and poor patient tolerance might limit its use in clinical practice. We identified that low PETCO2 during low‐intensity (FW) exercise is associated with PAH exercise capacity, providing predictive information for PAH risk stratification and prognostication. ABSTRACT Background and objective Peak oxygen consumption (pVO2), determined from CPET, provides a valuable indication of PAH severity and patient prognosis. However, CPET is often contraindicated in severe PAH and frequently terminated prior to achievement of a sufficient exercise effort. We sought to determine whether in PAH low‐intensity [i.e. freewheeling exercise (FW)] exercise reveals abnormal VE/VCO2 and PETCO2 responses that are associated with pVO2 and serve as indices of PAH risk stratification and mortality. Methods Retrospective analysis of CPET from 97 PAH patients and 20 age‐matched controls was undertaken. FW VE/VCO2 and PETCO2 were correlated with pVO2% age‐predicted. Prognostication analysis was conducted using pVO2 > 65% age‐predicted, as known to represent a low mortality risk. Primary outcome was mortality from any cause. Results FW PETCO2 was correlated with pVO2 (P 65% age‐predicted (best cut‐off value of 28 mm Hg). By Cox analysis, FW PETCO2