Disparity between EndoPAT measurement and brachial artery flow-mediated vasodilatation in hypertensive patients

Abstract

Background: EndoPAT measurement has been reported to be well correlated with brachial artery flow-mediated vasodilatation (FMD) in coronary artery disease. However, this relation is still controversial in hypertensive patients or normal subjects and the pathophysiological mechanisms of EndoPAT index is still not completely clarified. Purpose: The purpose of this study is to investigate the correlation of EndoPAT index with FMD and the physiological role of EndoPAT index in hypertension. Methods: To study this aim, we simultaneously measured EndoPAT index (RHI) and FMD by forearm occlusion technique, that is reported to be nitric oxide (NO) dependent, in 47 hypertensive patients without hypertensive complication (62±11 years old). BaPWV and augmentation index (AI@75bpm) by EndoPAT were also measured at the same time. Results: RHI did not correlate with FMD nor baPWV (r= 0.17, NS) while FMD also did not correlate with baPWV (r=0.08, NS). However, baPWV significantly correlated with AI@75bpm by EndoPAT (r=0.50, p<0.01). In conclusion: Augmentation index expressed as AI@75bpm by EndoPAT was associated with arterial stiffness measured by baPWV. However, there is no correlation between EndoPAT index of RHI and FMD in hypertensive patients, suggesting that the indexes reflect partially different vascular functions.