Longitudinal Changes in Coronary Artery Calcium Distribution and Atherosclerotic Cardiovascular Disease Risk

The Agatston score quantifies coronary artery calcium (CAC) burden but does not account for its spatial distribution. The CAC diffusivity index (DI) may refine cardiovascular risk stratification in individuals with Agatston CAC>0. This study assessed whether CAC distribution improves cardiovascular event prediction beyond the Agatston score in a young cohort.

Among DHS2 (Dallas Heart Study 2) participants with CAC>0 and no prior cardiovascular disease (35% of the cohort), we studied 1013 participants with CAC DI. CAC DI was calculated as 1-(CAC in most affected vessel/total CAC) and categorized as concentrated (<25th percentile), standard (25th-75th percentile), and diffuse (>75th percentile). Cox proportional hazards models and C-statistics assessed coronary heart disease (CHD), atherosclerotic cardiovascular disease, and mortality, adjusting for Agatston CAC, demographics, and traditional risk factors.

Mean±SD age was 55±9.4 years (49% women, and 47% Black), with a median follow-up of 9±2.5 years (57 CHD and 92 atherosclerotic cardiovascular disease events). Compared with a concentrated CAC pattern, standard and diffuse patterns were associated with incident CHD (hazard ratio, 5.97 [95% CI, 1.24-28.78] and 5.48 [95% CI, 1.04-29.04], respectively; P<0.05) but not atherosclerotic cardiovascular disease in fully adjusted models. Positive and negative changes in CAC DI were associated with increased CHD and atherosclerotic cardiovascular disease risk in models adjusted for pooled cohort equation variables, although effects were attenuated in fully adjusted models. Adding continuous CAC DI did not significantly improve model performance.

Higher CAC DI at baseline significantly contributes to adjusted models for incident CHD in a young population-based cohort, but temporal changes provided little additional benefit.