Cardiovascular Imaging and Strategies to Mitigate the Risk for Cardiac Events in Astronauts During Prolonged Spaceflight
Principal Investigator:
Benjamin D. Levine, M.D.
Organization:
The University of Texas Southwestern Medical Center at Dallas
On exploration missions, astronauts will not have access to comprehensive health care services for periods of two years, and possibly longer. Since the majority of astronauts are middle-aged, they are at risk for developing serious cardiovascular events which pose a threat to themselves and to the mission.
Dr. Benjamin D. Levine and colleagues will determine how to assess and minimize the risk of a catastrophic cardiovascular event in asymptomatic astronauts by looking at the risk of coronary events associated with changes in coronary artery calcium scores over time. The research will help determine whether this risk can be mitigated by increases in physical fitness or use of lipid-lowering therapy (drugs that lower cholesterol levels). This project will have widespread implications for public health and cardiovascular risk reduction in the population at large, especially for the asymptomatic individual.
NASA Taskbook Entry
This project will enhance current NASA cardiovascular disease risk-reduction strategies by partnering with investigators with the Aerobics Center Longitudinal Study (ACLS) and the Dallas Heart Study to determine how to minimize the risk of a catastrophic cardiovascular event in asymptomatic astronauts.
During an exploration-class space mission, such as a mission to Mars, astronauts will not have access to comprehensive health care services for periods of two years, and possibly longer. Since the majority of experienced astronauts are middle-aged (average age is 46, and the range is 33 to 58 years), they are at risk for developing serious cardiovascular events which are life-threatening for the astronaut and mission-threatening for NASA. The ability to identify "at risk" individuals, who are currently asymptomatic, is a topic of intense research within the cardiovascular community that is relevant both for NASA and public health.
The primary objective of this project is to determine the risk of coronary events associated with changes in coronary artery calcium (CAC) scores over time and to determine whether this risk can be mitigated by increases in physical fitness or use of lipid-lowering therapy.
Hypotheses
1) A change in coronary calcium score over time from <10 to >10 is associated with an increase in risk for coronary events; this risk is most prominent when the CAC score increases above a threshold level of 100.
2) The increased risk associated with increasing CAC scores is mitigated by increasing levels of physical fitness and/or the use of lipid-lowering therapy (statins).
Specific Aims
1) Identify all clinical events in the ACLS database. The researchers will identify and verify all myocardial infarctions, new onset angina and revascularization procedures in ACLS patients who fit the astronaut demographics and who have had more than one CAC measurement.
2) Update the ACLS database to include information about timing and dose of statin medications. This information will be linked with treadmill time and the clinical events from Aim 1 to develop robust, risk-prediction models.
After completion of these specific aims, the researchers will acquire information that is essential to inform decisions regarding astronaut selection for space exploration and that will allow flight surgeons to minimize the risk for catastrophic cardiovascular events. The project will have widespread implications for public health and cardiovascular risk reduction in the population at large, especially for the asymptomatic individual.
After completion of this project, the researchers will have determined the short term risk of cardiovascular events associated with changes in CAC scores, and its mitigation by fitness and/or medications. This information will inform decisions regarding astronaut selection for exploration class missions and will minimize the risk for catastrophic cardiovascular complications during spaceflight, yet at the same time, ensure that the most experienced and healthy crew are available to fly. The project will also have implications for public health and will clarify the meaning of changes in CAC scores, and produce strategies to reduce the risk for cardiovascular events in the population at large.
