Cardiopulmonary exercise testing in patients with pulmonary arterial hypertension and the new four strata risk prediction model

Cardiopulmonary exercise testing (CPET) is an established tool for follow-up of patients with pulmonary arterial hypertension (PAH). Recent PAH guidelines recommend a four-strata risk evaluation model at follow-up, not including CPET data. It is unknown how measures obtained at CPET relate to these new risk categories in patients with PAH.

To explore standard CPET variables in patients with PAH in relation to the recently suggested four-strata risk assessment categories in PAH.

A single-center, retrospective analysis of patients diagnosed with PAH group 1 who underwent CPET between years 2007-2022. Patients were categorized as: low risk, intermediate-low risk, intermediate-high risk or high risk based on natriuretic peptide (NT-ProBNP), six minute walking distance (6MWD) and World Health Organization functional class (WHO-FC).

In total, 23 patients (18 female, age 59 (41,69) years) with complete CPET and clinical data allowing accurate risk categorization were included. Thirteen patients were categorized as low-risk, six as intermediate-low and four as intermediate-high risk with no patient as high risk.

Figure 1 depicts CPET parameters comparing low-risk group, intermediate-low and intermediate-high risk group. Significant differences between the groups were found regarding peak oxygen uptake (VO2-peak) and the ventilation-to-carbon dioxide relationship (VE/VCO2-slope). More specifically, differences were significant between low-risk group vs intermediate-high risk group for VO2-peak (p-value 0.023) and VE/VCO2-slope (p-value 0.043).

We present that the new four-strata risk evaluation model in PAH is associated with marked differences in CPET parameters. This calls for further research evaluating the possible value of using CPET data in adjunct to the clinically based model.