Arterial structure and function in the years after long-duration spaceflight.

Spaceflight missions expose astronauts to an increased risk of oxidative stress and inflammatory damage that might accelerate the development or severity of cardiovascular disease. The purpose of this investigation was to determine whether long-duration spaceflight (>4 mo) results in structural and functional changes in the carotid and brachial arteries in the years after landing. Common carotid artery (CCA) intima-media thickness (cIMT), CCA distensibility and stiffness, and brachial artery endothelial-dependent and -independent vasodilation were measured in 13 International Space Station (ISS) astronauts (10 males and 3 females) approximately 180 and 60 days before launch, within 1 wk after landing, and up to 5 yr after landing. Additionally, we reviewed reports of cardiovascular-relevant parameters received from National Aeronautics and Space Administration (NASA) data archives within the Lifetime Surveillance of Astronaut Health obtained during flight certification and postflight annual physical examinations for eight of these astronauts. Postflight cIMT, CCA stiffness, distensibility, and brachial artery dependent- and -independent vasodilation were not different than preflight up to 5 yr after landing. Further, there were no records of newly diagnosed cardiovascular disease. Long-duration spaceflight missions on the ISS did not result in thickening of the carotid artery wall, increased CCA stiffness, endothelial dysfunction, or development of new symptoms or signs of cardiovascular disease in the first 5 years after long-duration spaceflight. Continued long-term surveillance of cardiovascular health in the larger astronaut cohort is necessary to characterize the lifetime risk of disease, particularly in astronauts who venture beyond low Earth orbit and are exposed to deep space radiation.NEW & NOTEWORTHY Previous investigations focused on in- and immediate postflight cardiovascular health indices. Here we report that in the 5 years after long-duration spaceflight in low Earth orbit, there was no evidence of increased carotid artery intima-media thickness or reduced brachial artery endothelium-dependent vasodilation in 13 middle-aged male and female astronauts. Additionally, biomarkers of oxidative stress and inflammation are dynamic in the days after landing and may not reflect the long-term health consequences of spaceflight.