PP.26.13

Abstract

Objective: Endothelial function by flow-mediated (FMD) and nitroglycerin-mediated vasodilations (NMD) was scarcely investigated in resistant hypertension. We aimed to assess the independent correlates of FMD and NMD in resistant hypertensive patients, particularly their associations with ambulatory blood pressures (BP) and nocturnal BP fall patterns. Design and method: In a cross-sectional study, 280 resistant hypertensives performed 24-hour ambulatory BP monitoring, carotid-femoral pulse wave velocity, polysomnography, and brachial artery FMD and NMD by high-resolution ultrasonography. Independent correlates of FMD, NMD and brachial artery diameter were assessed by multiple linear and logistic regressions. Results: Median (interquartile range) FMD was 0.75% (-0.6 – 4.4%) and NMD was 11.8% (7.1 – 18.4%). Baseline brachial artery diameter and diabetes were independently associated with both FMD and NMD. Older age and prior cardiovascular diseases were associated with altered FMD, whereas higher nighttime systolic BP and lower nocturnal systolic BP fall were associated with impaired NMD. Moreover, there was a significant gradient of impaired NMD according to blunted nocturnal BP decline patterns (p for trend = 0.001). Brachial artery diameter was independently associated with age, gender, body mass index, albuminuria and nocturnal SBP fall. Further adjustments to blood flow velocity, aortic stiffness, plasma aldosterone concentration, and sleep apnea did not change these relationships. Conclusions: Nitroglycerin-mediated vasodilation, but not flow-mediated dilation, is independently associated with unfavorable nighttime BP levels and non-dipping patterns, and may be a better cardiovascular risk marker in patients with resistant hypertension. Brachial artery diameter also may provide additional prognostic information.