The effect of high altitude (2500 m) on incremental cycling exercise in patients with pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: a randomised controlled crossover trial.

Among predominantly low-risk patients with stable PAH/CTEPH, cycling exercise during the first day at 2500 m was well tolerated, but peak exercise capacity, blood oxygenation and ventilatory efficiency were lower compared with 470 m.