Background: Correlation between hemodynamics and degree of pulmonary vascular obstruction (PVO) is known to be poor in CTEPH which makes the selection of patients eligible for pulmonary endarterectomy (PEA) challenging. It can be postulated that this poor relation is caused by small vessel arteriopathy, which might explain different postoperative hemodynamics and exercise capacity in patients with mild CTEPH and hemodynamically severe CTEPH, but similar PVO. We evaluated the effects of PEA on hemodynamics and exercise physiology in mild and severe CTEPH patients, matched for PVO

Methods: 18 CTEPH patients with a mild hemodynamic profile (mPAP between 25 and 30 mmHg at rest) and 18 CTEPH patients with a more severe hemodynamic profile (mPAP > 30 mmHg), matched by age, gender and PVO, were retrospectively studied. Cardio-pulmonary exercise testing parameters were evaluated at baseline and 18 months following PEA.

Results: At baseline exercise capacity, defined as oxygen uptake, was less severely impaired in the mild CTEPH group compared the severe CTEPH group. After PEA, in the mild CTEPH group, ventilatory efficiency and oxygen pulse improved significantly (p < 0.05), however the change in ventilatory efficiency and oxygen pulse was smaller compared to the severe CTEPH group. Only in the severe CTEPH group exercise capacity improved significantly (p<0.001).

Conclusion: Patients with hemodynamically mild and severe CTEPH and comparable PVO improve to similar hemodynamic status and level of exercise capacity after PEA.