@article {Schneider00314-2021, author = {Simon R. Schneider and Laura C. Mayer and Mona Lichtblau and Charlotte Berlier and Esther I Schwarz and St{\'e}phanie Saxer and Lu Tan and Michael Furian and Konrad E Bloch and Silvia Ulrich}, title = {Effect of a daytrip to altitude (2500 m) on exercise performance in pulmonary hypertension {\textendash} randomized cross-over trial}, elocation-id = {00314-2021}, year = {2021}, doi = {10.1183/23120541.00314-2021}, publisher = {European Respiratory Society}, abstract = {Question addressed by the study To investigate exercise performance and hypoxia-related health-effects in patients with pulmonary hypertension (PH) during a high-altitude sojourn.Patients and Methods In a randomized crossover trial in stable (same therapy for \>4 weeks) patients with pulmonary arterial or chronic thromboembolic PH (PAH/CTEPH) with resting PaO2 >=7.3kPa, we compared symptom-limited constant work-rate exercise test (CWRET) cycling time during a daytrip to 2500 m versus 470 m. Further outcomes were symptoms, oxygenation and echocardiography. For safety, patients with sustained hypoxemia at altitude (SpO2\<80\% \>30 min or \<75\% \>15 min) received oxygen therapy. (ClinicalTrials.gov: NCT03637153)Results 28 PAH/CTEPH-patients (15/13), 13 females, mean{\textpm}sd age 63{\textpm}15y were included. After \>3 h at 2500 m versus 470 m, CWRET-time was reduced to 17{\textpm}11 versus 24{\textpm}9 min (mean-difference 95\%CI) -6(-10 to -3) corresponding to -27.6\% (-41.1 to -14.1) p\<0.001 but similar Borg-dyspnea scale. At altitude, PaO2 was significantly lower (7.3{\textpm}0.8 versus 10.4{\textpm}1.5kPa; -3.2(-3.6 to -2.8)), whereas heart rate and tricuspid regurgitation pressure gradient (TRPG) were higher (86{\textpm}18 versus 71{\textpm}16 bpm; 15(7 to 23) and 56{\textpm}25 versus 40{\textpm}15mmHg; (17(9 to 24)) and remained so until end-exercise, all p\<0.001. The TRPG/cardiac output slope during exercise was similar at both altitudes. Overall, 3/28 (11\%) patients received oxygen at 2500 m due to hypoxemia.Conclusion This randomized cross-over study showed that the majority of PH-patients tolerate a daytrip to 2500 m well. At high versus low altitude, the mean exercise time was reduced, albeit with a high inter-individual variability, and pulmonary artery pressure at rest and during exercise increased, but pressure-flow slope and dyspnoea were unchanged.FootnotesThis manuscript has recently been accepted for publication in the ERJ Open Research. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJOR online. Please open or download the PDF to view this article.Conflict of interest: Dr. Schneider has nothing to disclose.Conflict of interest: Dr. Mayer has nothing to disclose.Conflict of interest: Dr. Lichtblau has nothing to disclose.Conflict of interest: Dr. Berlier has nothing to disclose.Conflict of interest: Dr. Schwarz has nothing to disclose.Conflict of interest: Dr. Saxer has nothing to disclose.Conflict of interest: Dr. Tan has nothing to disclose.Conflict of interest: Dr. Bloch has nothing to disclose.Conflict of interest: Dr. Ulrich reports grants from Johnson and Johnson SA, Switzerland, during the conduct of the study; grants from Swiss National Science Foundation, grants from Zurich Lung, grants and personal fees from Orpha Swiss, personal fees from Actelion SA, personal fees from MSD SA, outside the submitted work; .}, URL = {https://openres.ersjournals.com/content/early/2021/06/25/23120541.00314-2021}, eprint = {https://openres.ersjournals.com/content/early/2021/06/25/23120541.00314-2021.full.pdf}, journal = {ERJ Open Research} }