Abstract 1704: Utility of Coronary Artery Calcium in Identifying Whether Metabolic Syndrome and Diabetes Are Coronary Heart Disease Risk Equivalents
Background and Objective: Diabetes mellitus (DM) is usually considered a coronary heart disease (CHD) risk equivalent, carrying a >2% per year risk of a hard CHD event; however, there has been debate as to whether DM should always be considered a CHD risk equivalent. It is also unclear if many persons with the metabolic syndrome (MetS) are at high risk. We examined whether subclinical disease evaluation by coronary artery calcium (CAC) may help identify those at highest risk.
Methods: In the Multiethnic Study of Atherosclerosis, an epidemiologic study of men and women aged 45– 84 without CVD at baseline, we followed 6,635 persons, including 881 (13.3%) with DM (fasting glucose ≥126 mg/dl or on medication) and 1,686 (25.4%) with MetS defined according to AHA/NHLBI criteria. We calculated the annualized risk of hard CHD events (myocardial infarction, resuscitated cardiac arrest, or CHD death) occurring over an average of 4.6 years of follow-up, according to level of CAC measured by CT. Cox regression examined risks, adjusted for Framingham risk score and ethnicity, according to disease group stratified by CAC levels.
Results: Unadjusted CHD event rates (% per year) (and in parenthesis, adjusted hazard ratios with 95% confidence intervals) according to MetS/DM and CAC groups are shown in the table⇓. Most persons with DM (66% or 578 of 881) had CAC scores below 100 and event rates averaging <1% per year, comparable to many without DM. While those with MetS or DM with increased CAC scores had the highest rates, many still did not reach the CHD risk equivalent criterion of 2% per year. In adjusted Cox regression, those with MetS or DM without CAC had event risks not significantly higher than those without MetS/DM without CAC; higher levels of CAC remained associated with substantially higher CHD event risks.
Conclusions: Our results raise question as to whether DM should generally be considered a CHD risk equivalent. CAC screening may help identify MetS and DM subjects at highest risk.