Objectives: We sought to assess characteristics of diffuse coronary artery calcium (CAC) phenotypes and their associations with cause-specific mortality. Background: CAC is a measure of subclinical atherosclerosis and improves risk stratification. CAC characteristics including vessel involvement, number of vessels, volume, and density have been shown to differentially impact risk. Less is known about clinical predictors of a diffuse CAC phenotype and its impact on cause-specific mortality. Methods: The CAC Consortium is a retrospective, multi-site cohort of 66,636 participants without CHD who underwent CAC scoring. Risk factor data were collected at enrollment or scan. Participants with CAC>0 were included—CAC area, CAC density, and the CAC index of diffusion (the percentage of total CAC in the vessel with the highest CAC score) were calculated and the association between CAC characteristics and CVD- and CHD-specific mortality was assessed. Results: In 28,147 study participants (mean age 58.3 years, 25% female, and 89.6% white), ~66% had ≥2 calcified vessels. Diabetes, hypertension, and hyperlipidemia were predictors of multivessel involvement (p<0.001). After controlling for CAC score, those with 4-vessel CAC had more CAC area involved with less dense calcification compared to those with 1-vessel involvement. After adjustment, those with CAC score 1-299 had a graded increase in CVD- and CHD-specific mortality with increasing vessel number compared with 1-vessel CAC. No difference was seen for individuals with CAC >300. Among those with multivessel CAC involvement, all-cause survival was significantly worse in diffuse compared to other phenotypes. Conclusion: Diffuse CAC involvement was characterized by less dense calcification, more CAC area, multiple coronary vessel involvement, and presence of certain traditional risk factors. Multivessel CAC is associated with increased CVD- and CHD-specific mortality, particularly among CAC scores 1-299.
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