Abstract 9731: Improved Risk Stratification with Vendor Independent Coronary Calcium Scores: Data from the Multi-Ethnic Study of Atherosclerosis (mesa)

Introduction: Coronary calcium score (CCS) plays a role in cardiovascular disease (CVD) risk calculators, but also reclassifies patients when considering statin therapy. However, CCS is still calculated following the Agatston methodology as developed on electron beam tomography (EBT) in the early 1990s. EBT has been replaced by multidetector computed tomography (MDCT). It is known that CCS differs substantially between MDCT-systems from different manufacturers, which can lead to risk reclassifications for 6.5% of examined individuals Aims: Our first aim was to identify CT system specific conversion factors to calculate a vendor-neutral Agatston score (rCCS). Second, we aimed to validate rCCS risk stratification for participants of the Multi-Ethnic Study of Atherosclerosis (MESA). Methods: As a first step, we calculated conversion factors between six state-of the-art CT systems and the reference EBT system used in the MESA study. For this purpose, we scanned two calcium-containing inserts, which were placed in a small and large anthropomorphic thorax phantom. Linear regression was used to find a model which converts vendor-specific CCS to vendor-independent rCCS. As a second step, we recalculated the non-zero Agatston scores of 550 MESA participants. Following the Youden method, we calculated an optimal cut-off point for rCCS. Results: The linear model for each CT system allowed for prediction of Agatston scores as measured on the EBT system (p=0.001). rCCS for GE LightSpeed, used in MESA, was calculated as rCCS=0.049+1.97xMESA Agatston score and rCCS=1.903+1.37xMESA Agatston score for small and large size, respectively. The median MESA Agatston score was 100.5 (26.3-379.5), and the median rCCS was 135.8 (35.6-508.6). Participants were assigned to a high Agatston category with Agatston scores exceeding 100 (50.2%) and 187 (43.1%) for CCS and rCCS, respectively. The hazard ratio for CVD of individuals with high Agatston scores increased from 1.88 (95%CI: 1.31-2.68, p=0.001) with MESA scores to 2.15 (95%CI: 1.52-3.05, p=0.001) with rCCS. rCCS reclassified 39 participants into the lower risk group, without statin therapy. Conclusions: In conclusion, based on these preliminary results, rCCS may improve patient classification for statin therapy.