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Updated: Jun 8, 2026
Ultrasound Assessment of Endothelial-Dependent Flow-Mediated Vasodilation of the Brachial Artery in Clinical Research
Published on: October 22, 2014
Prevalence of impaired flow-mediated epicardial vasodilation among different types of coronary flow regulation
Ines Valenta1, Mohammad Alavi1, Ashwin S Parihar1
1Mallinckrodt Institute of Radiology, Division of Nuclear Medicine - Cardiovascular, Washington University in St. Louis School of Medicine, St. Louis, MO, USA.
Insights
Impairment of flow-mediated epicardial vasodilation (IEV) affects nearly half of symptomatic patients with normal coronary microvascular function. Identifying IEV is crucial for optimizing prognostication in cardiovascular patients.
Area of Science:
- Cardiology
- Vascular Biology
- Medical Imaging
Background:
- Coronary microvascular dysfunction (CMD) is increasingly recognized in symptomatic patients.
- Epicardial vasodilation plays a role in coronary blood flow regulation.
- Assessing flow-mediated epicardial vasodilation (IEV) alongside microvascular function is important.
Purpose of the Study:
- To determine the prevalence of IEV in patients with normal and abnormal coronary microvascular function.
- To investigate the relationship between IEV and different patterns of CMD.
- To explore the diagnostic and prognostic implications of IEV.
Main Methods:
- 332 symptomatic patients underwent 13N-ammonia PET/CT for myocardial blood flow (MBF) assessment.
- Coronary microvascular function was categorized based on myocardial flow reserve (MFR).
- IEV was defined by the longitudinal hyperemic MBF gradient.
Main Results:
- IEV was present in 34.6% of the overall study population.
- Prevalence of IEV was highest (46.2%) in patients with normal coronary microvascular function (MFR ≥ 2.0).
- IEV prevalence was lower and comparable in classical CMD (13.3%) and endogenous CMD (17.9%).
Conclusions:
- Nearly half of symptomatic patients with normal global MFR may exhibit IEV.
- IEV provides important diagnostic and prognostic information.
- Assessment of IEV may enhance prognostication in cardiovascular patients.
Abstract:
To assess the prevalence of impairment of flow-mediated epicardial vasodilation (IEV) in the presence of normal and abnormal coronary microvascular function. In 332 consecutive symptomatic patients, global and longitudinal myocardial blood flow (MBF) at rest and during pharmacologically stimulated hyperemia was evaluated with 13N-ammonia positron emission tomography/computed tomography (PET/CT). Normal coronary microvascular function (nCMF) was defined by a myocardial flow reserve (MFR = MBFstress/MBFrest) of ≥ 2.0 (group 1; n = 210 (G1)), while an abnormal MFR of < 2.0 (predominantly due to decreases in hyperemic MBF) denoted classical CMD (group 2; n = 83 (G2)) or (predominantly related to increases in resting MBF ≥ 1.0mL/g/min) signified endogen CMD (group 3; n = 39 (G3)), respectively. Furthermore, normal flow-mediated epicardial vasodilation (NEV) was defined as longitudinal hyperemic MBF gradient < -0.10 mL/g/min, whereas a value ≥ -0.10 mL/g/min signified IEV.In the entire study population, IEV was present in 34.6.% (115/332). IEV was highest in group 1 (46.2%), while there was a comparable low prevalence between group 2 and group 3 (13.3% vs. 17.9%; p = 559). The hyperemic longitudinal MBF gradient was significantly higher in G1 compared to G2 (-0.28 ± 0.10 vs. -0.19 ± 0.08 mL/g/min; p ≤ 0.008), but comparable between group 1 and group 3 (-0.28 ± 0.10 and - 0.27 ± 0.10 mL/g/min; p = 0.795). The hyperemic longitudinal MBF gradient and ΔMBF Gradient correlated inversely with the global hyperemic MBF, respectively (r = 0.41, SEE = 0.09 and r = 0.34, SEE = 0.09, both p ≤ 0.001). Nearly half of symptomatic patients with normal global MFR may have IEV. As IEV carries important diagnostic and prognostic information, it may further optimize prognostication on cardiovascular individuals deserving further clinical testing.
