Abstract 12813: Cardiovascular Risk Factors Attenuate the Relationship Between Insulin Resistance and Development of Extracoronary Calcification in the Multi-Ethnic Study of Atherosclerosis
Background: Insulin resistance is associated with increased CVD risk, but its relationship to extracoronary calcification (ECC) is unclear. We hypothesized that insulin resistance, measured by the homeostatic model assessment (HOMA-IR), is independently associated with prevalence and incidence of ECC.
Methods: The Multi-Ethnic Study of Atherosclerosis (MESA) enrolled 6,814 participants aged 45–84 free of clinical CVD. We studied 5,984 of those not on diabetic medication (mean age 62; 53% female) who had all covariates of interest, including cardiac CT scans. ECC measures analyzed were calcium scores of the aortic valve (AVC), mitral valve (MVC), aortic wall (AWC) and aortic valve root (AVR); all ECC calcium was calculated using the Agatston algorithm. Incident ECC was defined as a calcium score > 0 on follow up scan (mean 2.4 y) among those with a baseline 0 score for each ECC measure. Odds ratios for ECC prevalence and incidence were obtained from separate logistic regression models adjusted for baseline demographics (model 1), then additionally for CVD risk factors and education (model 2). Incidence models were adjusted for time between CT scans, and their sample size varied by baseline ECC prevalence (n=3655–4702).
Results: Prevalence of ECC measures was: AVC 12%, MVC 9%, AWC 26%, AVR 32%; incidence was AVC 4%, MVC 4%, AWC 12%, AVR 14%. After adjustment for demographics, higher HOMA-IR had a significant, positive association with an increased prevalence of all four ECC measures, and greater incident MVC, AWC and AVR (table). Further adjustment attenuated most associations, with significance remaining for prevalent AWC and incident MVC.
Conclusion: We observed positive associations of insulin resistance to prevalent and incident ECC, though only prevalent AWC and incident MVC remained significant on further risk factor adjustment. While CVD risk factors may underlie the relationship of insulin resistance and most ECC, associations are heterogeneous by ECC site.
- © 2010 by American Heart Association, Inc.