Oxygen pulse kinetics and ventilatory inefficiency as markers of cardiovascular limitation on exercise in patients with mild pre-capillary pulmonary hypertension and exertional dyspnoea

ABSTRACT Introduction Cardiopulmonary exercise testing (CPET) quantifies exercise limitation and helps differentiate cardiovascular dysfunction from deconditioning in patients with exertional dyspnoea. In mild pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH), traditional CPET oxygen delivery parameters may not adequately distinguish cardiac limitation. We evaluated whether oxygen pulse (O₂ pulse) kinetics and the ratio of ventilation–carbon dioxide slope to peak oxygen uptake (VEVCO₂/peakVO₂) improve identification of cardiovascular limitation and prognostication. Methods We retrospectively analysed 289 consecutive patients referred for CPET. Patients were categorised into pre-capillary PH, no PH, or “unclassified” PH based on haemodynamics. O₂ pulse slopes were calculated across exercise phases, and qualitative curve patterns were classified. VEVCO₂/peakVO₂ was derived from standard CPET parameters. Logistic regression assessed predictors of cardiac dysfunction (peak O₂ pulse