Time‐Course Analysis of Flow Mediated Dilation for the Evaluation of Endothelial Function After a High‐Fat Meal in African Americans

BACKGROUND: Flow‐mediated dilation (FMD) is used to assess endothelial function through changes in vascular diameter after hyperemia. High‐fat meal (HFM) has been shown to induce endothelial dysfunction; recent studies, however, reported conflicting results in obese African American women (AAW). Differences in the method used to analyze FMD may explain these discrepancies. METHODS AND RESULTS: In protocol 1, we assessed the time course of FMD and compared the repeatability of FMD using the individual maximum peak dilation (FMD (peak)) and the dilation at 60 seconds (FMD (60)). Sixteen AAW (age, 42±10.4 years; body mass index [BMI], 39±5.8 kg/m(2)) were studied on 2 occasions, 4 weeks apart, under fasting conditions (study 1 and study 2). In protocol 2, we used the most repeatable measurement from protocol 1 to assess changes in endothelial function after an HFM in 17 AAW (agen 42±11.1 years; BMIn 38±5.6 kg/m(2)). We found that FMD (peak) was the most repeatable measurement (N=16; study 1, 5.31±3.12% and study 2, 5.80±2.91%; r=0.94). After an HFM, the baseline brachial artery diameter significantly increased at 2 hours (0.10 mm; 95% confidence interval [CI], 0.01–0.18; P=0.03) and at 4 hours (0.17 mm; 95% CI, 0.09–0.25; P<0.001). At 2 hours, the FMD (peak) decreased compared with pre‐HFM (−1.76; 95% CI, −3.55–0.02; P≤0.05). CONCLUSIONS: The individual's maximum peak dilation after hyperemia is the most consistent measure to assess the effect of an HFM on endothelial function. Endothelial dysfunction occurred at 2 hours after an HFM in AAW. CLINICAL TRIAL REGISTRATION: URL: https://clinicaltrials.gov/ Unique identifiers: NCT01334554 and NCT02126735.