Assessing Level of Agreement for Atherosclerotic Cardiovascular Disease Risk Categorization Between Coronary Artery Calcium Score and the American College of Cardiology/American Heart Association Cardiovascular Prevention Guidelines and the Potential Impact on Treatment Recommendations

The 2013 American College of Cardiology/American Heart Association cardiovascular prevention guidelines use a new pooled cohort equation (PCE) to predict 10-year risk of atherosclerotic cardiovascular disease (ASCVD) events which form the basis of treatment recommendations. Coronary artery calcium score (CACS) has been proposed as a means to assess atherosclerotic risk. We sought to study the level of agreement in predicted ASCVD risk by CACS and PCE-calculated models and the potential impact on therapy of additional CACS testing. We studied 687 treatment naive, consecutive patients (mean age 53.5 years, 72% men) who had a CACS study at our institution. Clinical and imaging data were recorded. ASCVD risk was calculated using the published PCE-based algorithm. CACS-based risk was categorized by previously published recommendations. Risk stratification comparisons were made and level of agreement calculated. In the cohort, mean ASCVD PCE-calculated risk was 5.3 ± 5.2% and mean CACS was 80 ± 302 Agatston units (AU). Of the intermediate PCE-calculated risk (5% to <7.5%) cohort, 85% had CACS <100 AU. Of the cohort categorized as reasonable to treat per the ASCVD prevention guidelines, 40% had a CACS of 0 AU and an additional 44% had CACS >0 but <100 AU. The level of agreement between the new PCE model of ASCVD risk and demonstrable coronary artery calcium is low. CACS testing may be most beneficial in those with an intermediate risk of ASCVD (PCE-calculated risk of 5% to <7.5%) where, in approximately half of patients, CACS testing significantly refined risk assessment primarily into a very low–risk category.