Predictors of Coronary Artery Calcium and Long‐Term Risks of Death, Myocardial Infarction, and Stroke in Young Adults

Background Coronary artery calcium (CAC) is well‐validated for cardiovascular disease risk stratification in middle to older–aged adults; however, the 2019 American College of Cardiology/American Heart Association guidelines state that more data are needed regarding the performance of CAC in low‐risk younger adults. Methods and Results We measured CAC in 13 397 patients aged 30 to 49 years without known cardiovascular disease or malignancy between 1997 and 2009. Outcomes of myocardial infarction (MI), stroke, major adverse cardiovascular events (MACE; MI, stroke, or cardiovascular death), and all‐cause mortality were assessed using Cox proportional hazard models, controlling for baseline risk factors (including atrial fibrillation for stroke and MACE) and the competing risk of death or noncardiac death as appropriate. The cohort (74% men, mean age 44 years, and 76% with ≤1 cardiovascular disease risk factor) had a 20.6% prevalence of any CAC. CAC was independently predicted by age, male sex, White race, and cardiovascular disease risk factors. Over a mean of 11 years of follow‐up, the relative adjusted subhazard ratio of CAC >0 was 2.9 for MI and 1.6 for MACE. CAC >100 was associated with significantly increased hazards of MI (adjusted subhazard ratio, 5.2), MACE (adjusted subhazard ratio, 3.1), stroke (adjusted subhazard ratio, 1.7), and all‐cause mortality (hazard ratio, 2.1). CAC significantly improved the prognostic accuracy of risk factors for MACE, MI, and all‐cause mortality by the likelihood ratio test ( P <0.05). Conclusions CAC was prevalent in a large sample of low‐risk young adults. Those with any CAC had significantly higher long‐term hazards of MACE and MI, while severe CAC increased hazards for all outcomes including death. CAC may have utility for clinical decision‐making among select young adults.