Determinants of Incident Atherosclerotic Cardiovascular Disease Events among Those with Absent Coronary Artery Calcium: Multi-Ethnic Study of Atherosclerosis

Background: The 2018 American Heart Association/American College of Cardiology/Multisociety cholesterol guideline states that statin therapy may be withheld or delayed among intermediate-risk individuals in the absence of coronary artery calcium (CAC=0). We evaluated whether traditional cardiovascular risk factors are associated with incident atherosclerotic cardiovascular disease (ASCVD) events among individuals with CAC=0 over long-term follow-up. Methods: We included participants with CAC=0 at baseline from the MESA (Multi-Ethnic Study of Atherosclerosis), a prospective cohort study of individuals free of clinical ASCVD at baseline. We used multivariable-adjusted Cox proportional hazards models to study the association between cardiovascular risk factors (cigarette smoking, diabetes, hypertension, preventive medication use [aspirin and statin], family history of premature ASCVD, chronic kidney disease, waist circumference, lipid and inflammatory markers) and adjudicated incident ASCVD outcomes. Results: We studied 3416 individuals (mean [SD] age 58 [9] years; 63% were female, 33% White, 31% Black, 12% Chinese American, and 24% Hispanic). Over a median follow-up of 16 years, there were 189 ASCVD events (composite of coronary heart disease and stroke) of which 91 were coronary heart disease, 88 were stroke, and 10 were both coronary heart disease and stroke events. The unadjusted event rates of ASCVD were ≤5 per 1000 person-years among individuals with CAC=0 for most risk factors with the exception of current cigarette smoking (7.3), diabetes (8.9), hypertension (5.4), and chronic kidney disease (6.8). After multivariable adjustment, risk factors that were significantly associated with ASCVD included current cigarette smoking: hazard ratio, 2.12 (95% CI, 1.32-3.42); diabetes: hazard ratio, 1.68 (95% CI, 1.01-2.80); and hypertension: hazard ratio, 1.57 (95% CI, 1.06-2.33). Conclusions: Current cigarette smoking, diabetes, and hypertension are independently associated with incident ASCVD over a 16-year follow-up among those with CAC=0.