Influence of Subclinical Atherosclerosis Burden and Progression on Mortality

Background: Atherosclerosis is a dynamic process. There is little evidence regarding whether quantification of atherosclerosis extent and progression, particularly in the carotid artery, in asymptomatic individuals predicts all-cause mortality.

Objectives: This study sought to evaluate the independent predictive value (beyond cardiovascular risk factors) of subclinical atherosclerosis burden and progression and all-cause mortality.

Methods: A population of 5,716 asymptomatic U.S. adults (mean age 68.9 years, 56.7% female) enrolled between 2008 and 2009 in the BioImage (A Clinical Study of Burden of Atherosclerotic Disease in an At Risk Population) study underwent examination by vascular ultrasound to quantify carotid plaque burden (cPB) (the sum of right and left carotid plaque areas) and by computed tomography for coronary artery calcium (CAC). Follow-up carotid vascular ultrasound was performed on 732 participants a median of 8.9 years after the baseline exam. All participants were followed up for all-cause mortality, the primary outcome. Trend HRs are the per-tertile increase in each variable.

Results: Over a median 12.4 years' follow-up, 901 (16%) participants died. After adjustment for cardiovascular risk factors and background medication, baseline cPB and CAC score were both significantly associated with all-cause mortality (fully adjusted trend HR: 1.23; 95% CI: 1.16-1.32; and HR: 1.15; 95% CI: 1.08-1.23), respectively (both P < 0.001), thus providing additional prognostic value. cPB performed better than CAC score. In participants with a second vascular ultrasound evaluation, median cPB progressed from 29.2 to 91.3 mm³. cPB progression was significantly associated with all-cause mortality after adjusting for cardiovascular risk factors and baseline cPB (HR: 1.03; 95% CI: 1.01-1.04 per absolute 10-mm³ change; P = 0.01).

Conclusions: Subclinical atherosclerosis burden (cPB and CAC) in asymptomatic individuals was independently associated with all-cause mortality. Moreover, atherosclerosis progression was independently associated with all-cause mortality.