Abstract
The long-term prognostic significance of a coronary artery calcium (CAC) score of 0 is poorly defined in younger adults. We evaluated this among participants aged 45 to 55 years from the Multi-Ethnic Study of Atherosclerosis, and assessed whether additional biomarkers can identify subgroups at increased absolute risk. We included 1,407 participants (61% women) without diabetes or severe hypercholesterolemia, with estimated 10-year risk <20% and CAC = 0. We evaluated all and hard cardiovascular disease (CVD) events, overall and among subjects with each of the following: high-sensitivity C-reactive protein levels ≥2 mg/L, homocysteine ≥10 µmol/L, high-sensitivity cardiac troponin T ≥95th percentile, lipoprotein (a) >50 mg/dl, triglycerides ≥175 mg/dl, apolipoprotein B ≥130 mg/dl, albuminuria, thoracic aortic calcium, aortic valve calcium (AVC), mitral annular calcium, ankle-brachial index <0.9, any carotid plaque, and maximum internal carotid artery intima-media thickness (ICA-IMT) ≥1.5 mm. Median follow-up was 16 years, and overall CVD event rates were low (4% at 15 years). For most exposures evaluated, rates of all CVD events were <6 per 1,000 person-years, except for ICA-IMT ≥1.5 mm (6.43) and AVC (13.8). The number needed to screen to detect ICA-IMT ≥1.5 mm was 8, and 84 for AVC. Among participants with borderline/intermediate risk or premature family history, hard CVD event rates were <7 per 1,000 for most exposures, except for ICA-IMT ≥1.5 mm (8.25), albuminuria (8.30), and AVC (13.47). Nonsmokers and those with ICA-IMT <1.5 mm had very low rates. In conclusion, our results demonstrate a favorable long-term prognosis of CAC = 0 among adults aged ≤55 years, particularly among nonsmokers. ICA-IMT testing could be considered for further risk assessment in adults ≤55 years with CAC = 0 and uncertain management.