Abstract 16803: Number of Vessels with Coronary Artery Calcium and Improved Prediction of All-Cause Mortality

Abstract

Background: While the traditional Agatston coronary artery calcium (CAC) score is a powerful predictor of mortality, it is unknown if inclusion of regional distribution of calcified plaque improves risk prediction.

Methods: We retrospectively studied 23,058 patients from two sites (Torrance,CA and Columbus, OH) referred for clinical CAC scoring to enhance risk stratification. Approximately 61% of patients had CAC (N=14,084). Multi-territory CAC was defined by the number of vessels with CAC (scored 1 to 4, including the left main). Increasingly “diffuse” CAC was defined by decreasing percentage of CAC found in a single vessel (score in most calcified vessel / total score). All-cause mortality was ascertained in 100% of patients via search of the social security death index.

Results: Mean age of the population was 55 ± 11 years, with 69% men. Median follow-up was 6.6 ± 1.7 years. There were 584 deaths (2.5%). Considerable heterogeneity existed between CAC score group and number of calcified vessels (CAC 1-100: 51% 1-vessel, 34% 2-vessel, 14% 3-vessel, 2% 4-vessel; CAC 101-400: 11% 1-vessel, 35% 2-vessel, 44% 3-vessel, 10% 4-vessel). Within a calcium score group, the number of vessels with CAC strongly predicted increased mortality (see graph). In multivariable Cox models adjusted for age, gender, and the total CAC score, increasing number of vessels with CAC was associated with greater mortality (2-vessel: hazard ratio [HR] 1.52, 3-vessel: HR 1.97, 4-vessel: HR 2.32). In those with 2 or more calcified vessels, increasingly “diffuse” CAC distribution was associated with worse prognosis after adjustment for the CAC score (p=0.025), particularly when CAC 101-400. CAC score in individual coronaries, including the left main, did not improve the predictive value of the total CAC score (all p=NS).

Conclusions: Multi-vessel and increasingly “diffuse” CAC are associated with poor prognosis. These measures improve the prognostic power of the traditional Agatston CAC score.