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Human Research Program

Cardiovascular Imaging and Strategies to Mitigate the Risk for Cardiac Events in Astronauts During Prolonged Spaceflight

Completed Technology Project

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All aims have been accomplished. Because this section will be made publicly available, a modified selection from "main findings" is reproduced here. 1). DEFINED HOW TO QUANTIFY PROGRESSION OF CAC: The most common clinical definition of >15% per year, which is used by NASA flight surgeons, is too sensitive to the baseline CAC and frequently gives erroneous information, especially in patients with low baseline levels of CAC (for example an increase of 1 to 2, 10 to 11, or 100 to 101 reflect a 100%, 10%, and 1% change, but would still reflect the same absolute change in CAC). Different methods can result in divergent classification in up to 30% of individuals. Although we could not define the "best" score, the Hokanson method, based on the square root of the change in CAC, seemed to be the most robust, and will be utilized in other publications. This paper has been accepted in the Journal of the American College of Cardiology (JACC): Imaging; Paixao ARM...Levine BD et al. Disagreement Between Different Definitions of Coronary Artery Calcium Progression. JACC: Imaging, 2014, in press. 2). MADE THE NOVEL, CLINICALLY IMPORTANT OBSERVATION THAT THE FINAL CAC SCORE, RATHER THAN A MEASURE OF DISEASE PROGRESSION IS THE MOST IMPORTANT PIECE OF INFORMATION FOR PREDICTING CLINICAL EVENTS. So if serial CAC scanning is performed by flight surgeons, the latest scan should be used for risk assessment; knowledge of the change in CAC leading to this subsequent score will provide no independent prognostic information. This new finding obviates the need for complex calculations regarding rate of progression, and emphasizes that risk for future events depends mainly on the overall atherosclerotic burden, not on how fast the diseases progresses. Radford NB...Levine BD et al. Baseline Value, Follow-Up Value and Progression Rate of Coronary Artery Calcification Score and Risk of Incident Cardiovascular Disease Events. Submitted JAMA 08/2014 3). HIGHER DEGREES OF FITNESS MITIGATE THE EFFECT OF CAC AT ANY AGE OR LEVEL OF CAC. DeFina LF...Levine BD et al. Cardiorespiratory Fitness, Coronary Artery Calcium and Cardiovascular Disease Events. To be presented at American Heart Association meetings 2014; referenced as Circulation 2014; abstract in press. 4). DEVELOPED THE ASTRO-CHARM (Cardiovascular Health and Risk Modification). This score is the only system available which quantifies global cardiovascular risk in a relatively young population like the astronaut corps, using routine clinical information plus a CAC score. The final results from Astro-CHARM, including the functional calculator were delivered to NASA and the Human Research Program (HRP) in February 2014, and is actively being used by flight surgeons now. 5). DEMONSTRATED THAT INCREASED FITNESS PROTECTS AGAINST THE DEVELOPMENT OF DIABETES IN PATIENTS ON STATINS. Radford NB...Levine BD et al. Impact of Fitness on Incident Diabetes from Statin Use in Primary Prevention. Submitted Mayo Clinic Proceedings 07/2014. More »

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