Background: WHO Group 1 pulmonary arterial hypertension (PAH) is a progressive and potentially fatal disease. Individuals living at higher altitude are exposed to lower barometric pressure and hypobaric hypoxemia. This may result in pulmonary vasoconstriction and contribute to disease progression. We sought to examine the relationship between living at moderately high altitude and PAH characteristics. Methods: Forty-two US centers participating in the Pulmonary Hypertension Association Registry (PHAR) enrolled patients who met the definition of WHO Group 1 PAH. We utilized baseline data and patient questionnaire responses. Patients were divided into two groups: moderately high altitude residence (home >4,000 ft) and low altitude residence (home <4,000 ft) based on zip-code. Clinical characteristics, hemodynamic data, patient demographics and patient reported quality of life metrics were compared. Results: Controlling for potential confounders (age, sex at birth, body mass index (BMI), supplemental oxygen use, race, 100-day cigarette use, alcohol use, and PAH medication use), subjects residing at moderately high altitude had a 6-minute walk distance (6MWD) 32 meters greater than those at low altitude, despite having a pulmonary vascular resistance (PVR) that was 2.2 Wood units (WU) higher. Additionally, those residing at moderately high altitude had 3.7 times greater odds of using supplemental oxygen. Conclusion: Patients with PAH who live at moderately high altitude have a higher PVR and are more likely to need supplemental oxygen. Despite these findings, moderately high altitude PHAR patients have better functional tolerance as measured by 6MWD. It is possible that a âhigh-altitude phenotypeâ of PAH may exist. These findings warrant further study.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.