Abstract P213: Characterizing The Distribution Of Coronary Artery Calcification In The 75-and-older Population: The Atherosclerosis Risk In Communities Study

Introduction: The coronary artery calcium (CAC) score is a strong predictor of atherosclerotic cardiovascular disease (ASCVD) events. Current clinical practice guidelines recommend using a CAC score of 100 or age-, sex-, and race-specific 75 th percentile as thresholds of high risk for guiding preventive therapy for ASCVD. On the low end of the spectrum, zero CAC attracts attention as a potent negative predictor of ASCVD and may be used to “de-risk” individuals who may safely defer aggressive preventive therapy. However, due to sparse data on CAC in the age 75+ population, the value of these CAC thresholds in older adults is uncertain. Objective: To understand the distribution of CAC (75 th percentile, CAC 100, and zero CAC) in adults aged 75+. Methods: We assessed 2,303 ARIC Visit 7 (2018-2019) participants age 75+ years without clinical coronary heart disease (CHD) who underwent CAC scanning (median age 80 years, 39% males). Demographic-specific percentiles of the CAC distribution across age were estimated nonparametrically with pooled residual ranking and locally weighted regressions. Results: Male-white and male-black participants had lower prevalence of zero CAC than female-white and female-black participants (4% and 10% versus 13% and 16%, respectively). CAC scores tended to increase with age across race and sex strata but appeared to peak at an old age threshold (between age~85-95) ( Figure ). Regardless of age, sex, and race, a majority of individuals in this age range had CAC >100 ( Figure , green 50 th percentile line exceeds red dashed CAC 100 line at most ages). Conclusions: In the largest US cohort of community-dwelling adults aged 75+ free of clinical CHD with CAC data, the prevalence of zero CAC was approximately 4-16%. We also confirmed a general age-dependent increase in CAC. Using CAC >100 as a threshold for high ASCVD risk would categorize the majority of older adults age 75+ as high risk. Alternatively, our demographic-specific CAC percentiles may be a valuable tool for interpreting CAC in the age 75+ population.