Peripheral Endothelial Function and Coronary Flow Velocity Reserve Are Not Associated in Women with Angina and No Obstructive Coronary Artery Disease: The iPOWER Study.

PURPOSE: We investigated whether impaired flow-mediated dilation (FMD) and plasma biomarkers reflecting endothelial dysfunction are associated with coronary microvascular dysfunction (CMD) in women with angina and no obstructive coronary artery disease (CAD).
METHODS: Patients (n = 194) were randomly selected women with angina pectoris and no obstructive CAD (<50% stenosis). A reference population of asymptomatic women without CAD (n = 25) was included. We measured FMD in the brachial artery by high-resolution ultrasound. Coronary flow velocity reserve (CFVR) was assessed by transthoracic Doppler flow echocardiography (TTDE) of the left anterior descending artery during rest and high-dose dipyridamole infusion. CMD was defined as CFVR <2.
RESULTS: FMD and CFVR were measured in 128 patients and 21 controls. Mean (SD) age was 64.5 (8.9) years, mean CFVR was 2.3 (2.0-2.7), and mean FMD was 8.4% (4.8%) in angina patients. Angina patients had a higher risk factor burden compared with the reference population. Measures of peripheral endothelial dysfunction and endothelial plasma biomarkers did not differ according to angina or CFVR. CFVR and FMD did not correlate (Spearman ρ = -0.07, p = 0.45).
CONCLUSIONS: FMD and biomarkers of endothelial dysfunction did not identify individuals with CMD assessed as impaired CFVR by TTDE in women with angina and no obstructive CAD.