The effect of high altitude (2500m) on incremental cycling exercise in patients with pulmonary vascular disease. A randomized controlled cross-over trial

Objective: Physical activities at high altitude (HA) including hiking or skiing  is an increasing wish also for stable patients with precapillary pulmonary hypertension (PH) due to pulmonary vascular disease (PVD). We investigated the effect of HA on cycling exercise performance in patients with stable PVD. Methods: 27 (12 female, age 61±14yrs) stable, at low altitude (LA) non-hypoxemic patients with pulmonary arterial or distal chronic thromboembolic PH performed two incremental exercise tests until exhaustion, 1 at LA (470 m) and 1 at HA (2500 m) in a randomized-controlled cross-over trial. The main outcome was maximum work-rate (Wmax). Results: See table Wmax at LA was 120±64 W and significantly decreased by -11 W (95%CI: -16 to -5 W, p<0.001) at HA. Peripheral oxygen saturation (SpO2) at end-exercise was lower (-8% , p<0.001), the ventilatory equivalent for carbon dioxide was higher (+3.7, p= 0.003) at HA, while heart rate and blood pressure did not differ. There were no adverse events during exercise. Conclusion: In patients with stable PVD, cycling exercise at 2500m was well tolerated but exercise capacity was slightly lower compared to 470m along with a lower blood oxygenation and inefficient ventilation.