Abstract 1255: Predictive Value of Brachial Flow-Mediated Dilation for Incident Cardiovascular Events in Population Based Adults Free of Cardiovascular Disease at Baseline: The Multi-Ethnic Study of Atherosclerosis.
Although brachial artery flow-mediated dilation (FMD) has been shown to predict recurrent cardiovascular (CV) events, its predictive value for initial CV events in low CV risk or healthy adults is not well studied. We assessed the predictive value of FMD for incident CV events in the Multi - Ethnic Study of Atherosclerosis (MESA). Brachial FMD was measured in 3027 out of 6814 subjects with mean(±SD) age 61.2 ± 9.9 years, participating in the MESA study, a population based cohort study of adults free of clinical CV disease at baseline recruited at six clinic sites in the USA. The cohort consisted of 50.2% females, 34.3% Caucasian, 19.7% Chinese, 20.8% African Americans and 25.1% Hispanics. Probability weighted Cox proportional hazard analysis was used to examine the association between FMD and five years of adjudicated incident CV events including myocardial infarction, resuscitated cardiac arrest, definite angina, probable angina (if followed by revasc), stroke, stroke death, CHD death, peripheral vascular disease and revascularization (CABG, PTCA or other revasc). Mean (SD) FMD was 4.4( 2.8)%. One hundred and ninety-eight (6.5%) of the subjects had an adjudicated CV event during the follow-up period. In the univariate probability weighted Cox Proportional hazard analysis FMD (%) was a significant predictor of CV events [hazard ratio per 1% increment; 0.86(95% CI, 0.80 – 0.92), p<0.0001]. However, after adjusting for age, gender, race/ethnicity, diabetes mellitus, cigarette smoking, systolic blood pressure, total and HDL cholesterol, heart rate, BMI, statins use and ACE inhibitor use, FMD was no longer significantly associated with cardiovascular events [hazard ratio; 0.96 (95% CI, 0.82 – 1.13), p=0.66). Similar results were observed when the analysis was stratified by race, gender, hypertension and diabetes status. The c statistics when traditional CV risk factors are in the model was 0.82 whilst the c statistics for FMD alone was 0.61. Brachial FMD is not an independent predictor of incident CV events in population based adults free of clinical CV disease at baseline. FMD may be a confounder or a mediator of the known association between traditional CV risk factors and incident CV event in this population.