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Updated: May 27, 2025
Oxygenation-sensitive Cardiac MRI with Vasoactive Breathing Maneuvers for the Non-invasive Assessment of Coronary Microvascular Dysfunction
Published on: August 17, 2022
Functional or structural impairment of flow-mediated epicardial vasodilation may precede coronary microvascular
Ines Valenta1, Salwa Mikhail2, Ashwin Singh Parihar1
1Mallinckrodt Institute of Radiology, Division of Nuclear Medicine, Cardiovascular Medicine, Washington University School of Medicine, St. Louis, MO, USA.
Background:
The aim was to investigate whether functional and/or structural impairment of flow-mediated epicardial vasodilation (IEV) may precede coronary microvascular dysfunction (CMD) in a cardiometabolic risk population.
Methods:
13N-ammonia positron emission tomography/computed tomography evaluated global and longitudinal myocardial blood flow (MBF) during pharmacologically induced hyperemia and at rest. Normal coronary microvascular function (nCMF) was defined by a myocardial flow reserve (MFR = MBFstress/MBFrest) of ≥ 2.0, while an abnormal MFR of < 2.0 (predominantly due to decreases in hyperemic MBF) denoted classical CMD. 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 signifiedIEV. Patients were grouped as follows: group 1 (G1): nCMF and NEV (n = 93); group 2 (G2): nCMF and IEV (n = 62), and group 3 (G3): CMD and IEV (n = 78). From non-gated CT, a semiquantitative four-point scoring system was used to indicate coronary artery calcifications score (CCS).
Results:
The prevalence of diffuse coronary artery calcification was highest in G1 with 51 %, followed by G3 with 46 % and G2 with 34 %. The extent of CCS was mild-to-moderate and did not differ significantly among groups (p = 0.222). Overall, IEV was present in 60 %, while there was a comparable prevalence of IEV between G2 and G3 (27 % and 33 %, p = 0.27). The hyperemic MBF gradient was highest in G2, intermediate in G3, and lowest in G1 (-0.22 ± 0.11 and -0.18 ± 0.10 vs. 0.03 ± 0.08 mL/g/min; p < 0.001, respectively).
Conclusions:
In this cardio-metabolic risk population, in about one third of these symptomatic patients functional and/or structural impairment of flow-mediated epicardial vasodilation may precede coronary microvascular dysfunction.
