Ventilatory Efficiency During Exercise in CTEPH and PAH Pre- and Post-Treatment
Esther I. Schwarz, Lara Benning, Zoe Bousraou, Julian Müller, Mona Lichtblau, Isabelle Opitz, Silvia Ulrich
https://doi.org/10.1002/pul2.70334
Abstract
Ventilatory inefficiency, assessed by the VE/VCO2 slope during cardiopulmonary exercise testing (CPET), is a key physiological marker. However, differences in ventilatory efficiency between chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary arterial hypertension (PAH), as well as their response to treatment, remain incompletely characterized. We retrospectively analyzed CPET data from 92 patients with CTEPH and 91 with PAH. Ventilatory efficiency (VE/VCO2 slope) and peak oxygen uptake (peak VO2) were compared at baseline and in treatment-naïve subgroups. Predictors of ventilatory efficiency were assessed using regression analyses. Longitudinal changes following treatment were evaluated in patients with serial CPETs. At baseline, ventilatory efficiency was significantly worse in CTEPH than in PAH (VE/VCO2 slope median (IQR) 39.8 (34.3–47.5) versus 35.9 (31–41.5), p < 0.001), despite less severe hemodynamic impairment. This difference persisted in treatment-naïve patients. In both groups, pulmonary vascular resistance, mean pulmonary artery pressure, and peak VO2 were independent predictors of the VE/VCO2 slope. Following treatment, ventilatory efficiency improved significantly in CTEPH (ΔVE/VCO2 slope −8, 95% CI − 13.3 to −4.2, p < 0.001), accompanied by an increase in peak VO2. Improvements were most pronounced after pulmonary endarterectomy. Patients with PAH showed only modest changes after initiation of targeted therapy. Ventilatory inefficiency is more pronounced in CTEPH than in PAH despite less severe resting hemodynamics. Treatment, particularly pulmonary endarterectomy, leads to substantial improvement in ventilatory efficiency in CTEPH, whereas changes in PAH are less pronounced. CPET-derived ventilatory efficiency may serve as a useful non-invasive marker of treatment response in pulmonary hypertension, particularly in CTEPH.
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