Cardiopulmonary exercise testing in severe pulmonary arterial hypertension: A more complete tool than six minute walk test?

The six minute walk test (6MWT) is the most commonly used test to measure functional capacity (FC) in pulmonary arterial hypertension (HAP). However, some limitations have been described. Cardiopulmonary exercise testing (CPET) is complex but adds objective parameters of FC derived both from stroke volume (SV) (peak O2 uptake, VO2; anaerobic threshold, AT; peak O2 pulse, PO2; systolic arterial pressure increase, SAPI) and ventilatory inefficiency due to ventilation/perfusion mismatching (CO2 equivalents at AT, CO2Eq; peak end tidal PO2 and PCO2, PetO2 and PetCO2). Purpose: analyze the role of CPET in assessing FC in PAH and compare it with 6MWT.