Cardiorespiratory reserve in patients with chronic thromboembolic pulmonary hypertension

Aim. To assess the cardiorespiratory reserve of patients with chronic thromboembolic pulmonary hypertension (CTEPH) depending on pulmonary hypertension severity.

Material and methods. This prospective study included 132 male patients with CTEPH admitted for elective surgical treatment from November 2018 to January 2025. Group 1 included 70 patients with mean pulmonary artery pressure (mPAP) ≤50 mm Hg. According to right heart catheterization data, group 2 included 62 patients with mPAP >50 mm Hg. All patients underwent cardiopulmonary exercise testing (CPET).

Results. According to CPET, all patients with CTEPH were characterized by reduced cardiovascular and respiratory reserves. Peak oxygen uptake (VO_2peak) was 44,3 (36,7‑61,1)% of the predicted level. A significant decrease in the effectiveness of pulmonary ventilation (VE/VCO₂ 49,5 (42,7‑54,0)) and a limitation of the oxygen pulse (8,1 (4,5‑10,0) ml/beat) were recorded during physical exercise. The average load power was 63,4 (53,1‑76,2) W.

Patients in group 2 had a lower right ventricular fractional area change, a reduced cardiac index, and the highest pulmonary vascular resistance compared to group 1. Compared to group 1, patients in group 2 had significantly reduced respiratory reserves due to a low VO_2peak of 11,2 (10,1‑12,9) and 13,8 (12,7‑15,8) ml/min/kg, respectively (p=0,01) and high VE/VCO₂ values of 52,3 (47,4‑56,5) and 45,6 (41,5‑49,5), respectively (p=0,04). A significantly reduced cardiovascular reactivity was also noted: maximum systolic and diastolic blood pressure were lower compared to group 1.

Conclusion. Cardiorespiratory reserve, according to CPET data, in patients with CTEPH is characterized by low aerobic capacity (VO_2peak 12,4 (10,6‑15,0) ml/min/kg) against the background of reduced pulmonary ventilation efficiency and limited cardiovascular performance during physical activity. Severe pulmonary hypertension is accompanied by a more significant decrease in respiratory reserve due to low VO_2peak and pulmonary ventilation efficiency, as well as significantly reduced cardiovascular reactivity during exercise.

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