Abstract 14517: Impact of Coronary Artery Calcium on Coronary Heart Disease Events In Individuals at the Extremes of Traditional Risk Factor Burden: The Multi-Ethnic Study of Atherosclerosis (MESA)
Background: The prognostic value of coronary artery calcium (CAC) in individuals at the extremes of risk factor (RF) burden remains uncertain. We sought to examine the interplay between burden of RF and CAC for the prediction of coronary heart disease (CHD) in individuals across the RF spectrum.
Methods: RF data was collected and CAC was measured in 6,698 individuals from the Multi-Ethnic Study of Atherosclerosis (MESA), an observational cohort of men and women aged 45-84 years free of clinical cardiovascular disease. The following risk factors were considered: 1) Cigarette smoking, 2) LDL ≥ 130mg/dl, 3) HDL ≤ 40mg/dl, 4) Hypertension, and 5) Diabetes Mellitus. Age-gender, MESA site, CAC score and RF adjusted hazard ratios (HR) for the primary end point of CHD events were calculated over a median follow-up of 5.8 years.
Results: There were 1,067 subjects (16%) with 0 RF, whereas 2,310 (35%), 2,116 (32%) and 1,205 (18%) had 1, 2 and ≥ 3 RF respectively. Among individuals without RF, 68% had CAC = 0, whereas 12% had CAC > 100. Among individuals with ≥ 3RF, 35% had CAC = 0, whereas 34% had CAC > 100. During follow-up, 274 (4.1%) CHD events occurred. The figure shows that no CHD events were observed in those with 0 CAC and no RF, whereas those with CAC > 100 and ≥ 3RF had the highest CHD rate. Individuals with no RF and CAC >100 had an event rate which was approximately 3x higher than the rate observed among individuals with ≥ 3RF and 0 CAC. The HR for individuals with CAC > 100 compared to those with CAC = 0 was 7.52 (4.92-11.49), while the HR for individuals with ≥ 3 RF compared to those with 0 RF was 4.82 (2.57-9.06).
Conclusion: In this multiethnic cohort, CAC was able to further risk stratify individuals at the extremes of traditional RF burden. Among individuals with 0 RF, traditionally classified as low risk, CAC > 100 was associated with an event rate of > 10/1,000 person-years. Among individuals with ≥ 3 RF, traditionally classified as high risk, CAC = 0 was associated with an event rate of < 5/1000 person-years.
- © 2011 by American Heart Association, Inc.