Coronary Artery Calcium, Aortic Calcification and Density in MESA - ABSTRACT
In the current healthcare environment, reducing costs by eliminating a second test (such as a dedicated
computed tomography [CT] for CAC) when clinically similar data is already available (such as from a non-
contrast chest CT (NCCT) ordered for another indication) is a laudable goal. More importantly, many cardiac
events could potentially be prevented if incidentally discovered CAC or aortic arch calcification (AAC) would
not only alert physicians to the presence of significant disease but would steer appropriate patients for lifestyle
and/or pharmacologic intervention. Finally, evaluating those with high CAC scores who do not suffer an event
over the next 20 years will identify factors that are protective, and can potentially reduce false positives
associated with CAC testing, avoiding downstream testing and medication use. The concomitant assessment
of CAC during lung cancer screening with NCCT, represents an opportunity to also identify asymptomatic
individuals at both decreased and increased cardiovascular (CVD) risk. Furthermore, evaluating advanced
metrics of CAC (ie- density and location) along with AAC to improve CAC performance, is unique.
This study poses to leverage the Multi-Ethnic Study of Atherosclerosis (MESA) as a rigorously compiled and
highly validated dataset using a comprehensively phenotyped, multi-racial and multi-ethnic cohort. We will
utilize the considerable resources already invested in the collection of almost 20,000 well performed NCCT to
determine prevalence, risk factor associations, and prognostic value using 20 years of careful adjudicated CVD
follow up and repeat imaging. Specifically, we will measure AAC, CAC, and density in 19,861 scans: 6,814
participants in the baseline study and 5,987 full lung CTs in participants of MESA Lung Study (3,187 in 2010-
12) and 2850 acquired during exam 6 (2016-2018). The scientific premise is that these extra-coronary
calcifications (ECC) may portend risk for CVD independent of CAC, and that non-contrast CT (such as those
obtained for lung cancer screening) can serve as a viable source of both CAC and ECC measurement. The
MESA Cohort permits a unique opportunity, with over 20 year follow up and committee adjudicated CVD
events, to allow establishment of prevalence and prognostic significance of CAC detection in a multi-ethnic
population based cohort, with consideration of prognostic potential of both calcium density and AAC. The hope
is that this may serve as a mechanism to deliver appropriate preventative treatment, emphasizing therapeutic
intervention for those who are at higher predicted risk at a given CAC threshold. These aspects are highly
innovative, as is the emphasis on evaluating calcium density as a de-risking, effect modifier for individuals with
higher CAC is unique to our knowledge. With achievement of the proposed study aims, a valuable
epidemiological database will be developed, and the opportunity to utilize existing NCCT for routine CVD risk
stratification will move closer to reality. We feel the proposal is highly significant with considerable potential to
exert a direct, positive impact on the approach to CVD prevention.