P1564Coronary artery disease detected on cardiac computed tomography scans is associated with low bone mineral density in female patients

Abstract

Background: Atherosclerosis and osteoporosis are both common diseases. There is some evidence to support an association between coronary calcification and low bone mineral density (BMD). With the extended use of cardiac computed tomography (CT) as the first line diagnostic tool for coronary artery disease (CAD), simultaneous evaluation of coronary calcification and BMD seem feasible. Purpose(s): The aim of this study was to assess the association between coronary artery calcification score (CACS) and thoracic BMD in a large group of patients with symptoms suggestive of CAD. Method(s): Patients were included consecutively at two Danish hospitals as part of the Dan-NICAD study. An experienced cardiologist performed the Agatston CACS. BMD measurements were performed on three thoracic vertebrae starting at the level of the left main coronary artery using quantitative CT and asynchronous calibration. We used the American College of Radiology cut-off values for lumbar spine quantitative CT to categorize patients into very low (<80 mg/cm3), low (80-120 mg/cm3), or normal BMD (>120 mg/cm3). Mean BMD as a continuous variable was used to test statistical significance between CACS groups and included in the multivariate regression analysis. Multivariate linear regression was performed using the following normally distributed variables; age, smoking status, dairy intake, exercise status, abdominal circumference, hip circumference, P-creatinine and postmenopausal status to assess the relationship between mean BMD and CACS groups. Result(s): A total of 1487 patients were included. Mean age was 57 years (range 40-80), 48% were men. The prevalence of any coronary artery calcification (CACS>0) was 49% (727/1487). Patients with very low BMD were more likely to have moderate (>0-399) (p<0.001) and high CACS (>399) (p<0.001) compared to patients with normal BMD. BMD decreased significantly with increasing calcification categorized according to CACS groups (CACS=0, CACS>0 to 399 and, CACS>399) in both men and women, except for a non-significant decrease in BMD between moderate (>0-399) and high (>399) CACS in men. Multivariate linear regression showed a negative correlation between BMD and CACS groups in women (beta =-5.37, p<0.01), but not in men (beta =-1.58, p=0.32). Conclusion(s): Our results indicate a highly significant association between coronary calcification and low bone mineral density in women, but not in men. The biological explanation for this gender difference is unknown, but could include differences in mineralization and vascular calcification processes related to menopause. The association may also be explained by common metabolic pathways or unknown confounders not adjusted for. Given the easy access to bone data from routine clinical CT scans, osteoporosis screening could be relevant in women with a high CACS.