Abstract Body (Do not enter title and authors here): Background: The Agatston score is established as the clinical measure of coronary artery calcium. However, prognostic implications of the overall number and location of calcified plaques remain unknown in the 75-and-older population.
Methods: We analyzed data from 1,746 participants in the ARIC study who underwent non-contrast cardiac-gated chest computed tomography (CT) at visit 7 (2018-19) and were free of cardiovascular disease (CVD) at baseline. In addition to quantifying the Agatston score, we also interpreted the total number of calcified plaques and their location (proximal [before the first major branch] vs. distal [after the first major branch]) in each coronary artery. Multivariable Cox proportional hazards models were used to quantify the association of calcified plaque number with CVD events (adjudicated myocardial infarction, stroke, and heart failure). Participants with zero plaque were treated as a reference, and those with at least one plaque were divided into quartiles of plaque number.
Results: During a median follow-up time of 2.8 (interquartile interval 2.4-3.3) years, there were 114 (6.5%) CVD events. After adjusting for traditional CVD risk factors, there was a dose-response relationship between overall calcified plaque number and CVD events (Model 1 in Table), with a hazard ratio of 8.17 (95% CI 2.44, 27.39) in plaque number ≥ 25 (Q4) vs. 0 (no plaques). The association remained statistically significant even after further adjusting for Agatston score (Model 2). When we analyzed proximal and distal plaques separately, the association was more evident in the proximal distribution (e.g., hazard ratio of Q4 vs. no plaques 3.95 (1.42, 11.00) for proximal vs. 1.38 (0.67, 2.85) for distal in Model 2).
Conclusion: Calcified coronary plaque number, especially in proximal arteries, was associated with incident CVD events beyond the traditional risk factors and the Agatston score in the 75-and-older population. Our findings suggest the possibility to further optimize the use of cardiac CT beyond the Agatston score for predicting CVD events in this population.