Prognostic value of follow-up cardiopulmonary exercise testing in pulmonary arterial hypertension

<bold>Introduction:</bold> Current guidelines recommend a four-strata model based on World Health Organization functional class (WHO-FC), 6-min walk distance (6MWD), and levels of brain natriuretic peptide (BNP) for risk stratification in patients with pulmonary arterial hypertension (PAH) during follow-up (Humbert et al <italic>Eur Resp J</italic> 2023). <bold>Aims:</bold> To explore the clinical relevance of cardiopulmonary exercise testing (CPET) as the exercise parameter in place of 6MWD at first reassessment after treatment in PAH. <bold>Methods:</bold> Incident treatment-naïve patients with idiopathic, heritable, drug/toxins-induced, and connective tissue disease-associated PAH were analysed at first follow-up. Cox regression models were used to identify CPET parameters associated with survival. A composite CPET score was derived by averaging risk scores for each prognostic CPET variable. Transplant-free survival was assessed using Kaplan–Meier analyses. <bold>Results:</bold> 262 patients were included. The final CPET score included peak oxygen uptake, the slope relating minute ventilation to carbon dioxide production, and peak oxygen pulse. The four-strata model based on WHO-FC, BNP, and CPET score predicted survival at the time of the first re-evaluation, with better accuracy than the model including 6MWD (c-index 0.81 vs 0.71, p<0.001). <bold>Conclusions:</bold> A simplified four-strata risk assessment tool incorporating the CPET score accurately predicted survival at follow-up in PAH <fig><object-id>erj;64/suppl_68/PA2494/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>