AHA Scientific Sessions 2026 Abstract · Nov 2, 2026
Coronary Artery Calcium Progression is Driven by Plaque Volume Rather Than Density
By Chritah R, Gershon G, Momin E et al.
Background: Emerging evidence suggests that calcified plaque volume and density may carry independent prognostic information beyond the CAC score, with higher calcium density often appearing protective and low-density, high-volume plaque representing a higher-risk phenotype. Few studies, however, have examined how CAC volume and density evolve over time in individuals undergoing repeat CAC CT imaging. Research Questions: Are annualized changes in calcified plaque volume and density on serial CAC CT correlated with one another and with upward CAC category progression and which component tracks category progression more closely? Methods: This study included asymptomatic adults without a history of cardiac disease who underwent serial non-contrast CAC CT between May 2011 and January 2023 with at least one year between examinations. Scans were processed with a validated artificial intelligence (AI) algorithm to derive CAC scores, calcified plaque volume, and mean lesion density. Plaque volume and density were annualized. CAC categories were None (0), Minimal (1-10), Mild (11-100), Moderate (101-400), and Severe (>400). Associations were assessed using Kendall's τ, ANOVA, trend testing, and multivariable partial correlation adjusted for baseline plaque and clinical covariates. Results: Among 1,898 patients (mean age: 54 years; 64% men; 85% White) with a mean interscan interval of 5.2 years, 1,352 patients presented with Minimal to No CAC (71%), 339 (18%) presented with Mild CAC, 175 (9%) Moderate, and 31 (1.6%) Severe CAC; at follow-up, 750 patients (39.5%) progressed to a higher category. Volume progression increased with baseline CAC burden, rising from 1 mm ³ /year among patients with Minimal to No CAC to 71 mm ³ /year among those with Severe CAC (τ = 0.54, p<0.001). Similar trends existed across category transitions (7, 20, and 59 mm ³ /year for Minimal-to-Mild, Mild-to-Moderate, and Moderate-to-Severe; p < 0.001). Density change showed the opposite pattern: it was weakly, inversely related to baseline category (τ = –0.08, p=0.005), while increasing most at lower-burden transitions (+5.8 HU/year, Minimal-to-Mild) and flattening at higher-burden ones (+1 HU/year, Moderate-to-Severe; p < 0.001). Volume and density changes were also not significantly related overall (τ = –0.016, p=0.52), by quartile (τ=–0.008, p=0.79), and after adjustment (partial ρ≈–0.03, p=0.36). Conclusion: In serial CAC CT, rising CAC reflects expanding plaque volume rather than density, and the two components progress independently. CAC score progression may therefore capture only part of evolving plaque biology, potentially masking density changes that carry distinct prognostic meaning.