Individuals with 0 risk factors and CAC >300 had a CHD event rate 3.5 times higher than those with ≥3 risk factors and CAC 0 (10.9 vs. 3.1 per 1000 person-years).
Cohort (n=6,698)
Yes
Does coronary artery calcium score predict coronary heart disease events in individuals at the extremes of traditional risk factor burden?
A high coronary artery calcium burden identifies individuals at elevated risk for CHD events even in the absence of traditional risk factors, whereas a CAC of 0 indicates low risk even among those with multiple risk factors.
Effect estimate: 3.5 times higher
Absolute Event Rate: 10.9% vs 3.1%
AIMS: We sought to evaluate the impact of coronary artery calcium (CAC) in individuals at the extremes of risk factor (RF) burden. METHODS AND RESULTS: 6698 individuals from the Multi-Ethnic Study of Atherosclerosis (MESA) were followed for coronary heart disease (CHD) events over mean 7.1 ± 1 years. Annualized CHD event rates were compared among each RF category (0, 1, 2, or ≥3) after stratification by CAC score (0, 1-100, 101-300, and >300). The following traditional modifiable RFs were considered: cigarette smoking, LDL cholesterol ≥3.4 mmol/L, low HDL cholesterol, hypertension, and diabetes. There were 1067 subjects (16%) with 0 RFs, whereas 1205 (18%) had ≥3 RFs. Among individuals with 0 RFs, 68% had CAC 0, whereas 12 and 5% had CAC >100 and >300, respectively. Among individuals with ≥3 RFs, 35% had CAC 0, whereas 34 and 19% had CAC >100 and >300, respectively. Overall, 339 (5.1%) CHD events occurred. Individuals with 0 RFs and CAC >300 had an event rate 3.5 times higher than individuals with ≥3 RFs and CAC 0 (10.9/1000 vs. 3.1/1000 person-years). Similar results were seen across categories of Framingham risk score. CONCLUSION: Among individuals at the extremes of RF burden, the distribution of CAC is heterogeneous. The presence of a high CAC burden, even among individuals without RFs, is associated with an elevated event rate, whereas the absence of CAC, even among those with many RF, is associated with a low event rate. Coronary artery calcium has the potential to further risk stratify asymptomatic individuals at the extremes of RF burden.
Silverman et al. (2013) conducted a cohort in Asymptomatic individuals at extremes of risk factor burden (n=6,698). Coronary artery calcium (CAC) score >300 vs. CAC score 0 was evaluated on Coronary heart disease (CHD) events (3.5 times higher). Individuals with 0 risk factors and CAC >300 had a CHD event rate 3.5 times higher than those with ≥3 risk factors and CAC 0 (10.9 vs. 3.1 per 1000 person-years).