Associations of urinary isoprostanes with measures of subclinical atherosclerosis: The Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND: Urinary isoprostanes are markers of systemic oxidative stress, which is implicated in the pathogenesis of atherosclerotic cardiovascular disease (ASCVD). Coronary artery calcium (CAC), thoracic aortic calcium (TAC) and carotid plaque are measure subclinical atherosclerosis and prognosticate ASCVD risk. We examined the associations between urinary isoprostane levels and measures of plaque prevalence, burden, incidence and progression across three vascular beds in a cohort from the Multi-Ethnic Study of Atherosclerosis. METHODS: Urinary levels of 8-isoprostane and 2,3-dinor-8-F(2)-isoprostane were measured in 1089 participants (mean ± SD 62 ± 8 years, 48% women) at baseline. Participants underwent computed tomography for CAC and TAC, and duplex ultrasound for carotid plaque. TAC and CAC were reassessed at 2.4 and 10 years, respectively. Regression models were adjusted for CVD risk factors. RESULTS: In adjusted models, there were no significant associations between isoprostane levels with CAC prevalence or progression. Highest versus lowest tertile of 8-isoprostane was associated with 28% lower prevalence of descending TAC at baseline [prevalence ratio (PR) 0.72 95% CI (0.56, 0.94)], while 1-SD higher 2,3-dinor-8-F(2)-isoprostane was associated with 96% higher incident ascending TAC at follow-up [Relative Risk 1.96 (1.24, 3.09)]. Highest versus lowest tertile of isoprostane measures were associated with 22% higher prevalence of carotid plaque [(PR 1.22 (1.04, 1.45)] and 14% difference [3,26] in greater extent of carotid plaque at baseline. CONCLUSIONS: Higher urinary isoprostanes were inconsistently associated with some measures of subclinical atherosclerosis by imaging. This suggests a limited role of urinary isoprostane levels as a prognostic marker for the development of ASCVD. TRIAL REGISTRATION: The MESA cohort design is registered at clinicaltrials.gov as follows: https://clinicaltrials.gov/ct2/show/NCT00005487.