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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.
Impaired epicardial vasodilation may precede coronary microvascular dysfunction in patients with cardiometabolic risk. This study found that in a significant portion of these patients, flow-mediated epicardial vasodilation issues appeared before coronary microvascular dysfunction.
Area of Science:
- Cardiovascular Medicine
- Medical Imaging
- Physiology
Background:
- Investigating the sequence of cardiovascular impairments in at-risk populations is crucial for understanding disease progression.
- Coronary microvascular dysfunction (CMD) and impaired flow-mediated epicardial vasodilation (IEV) are key concerns in cardiometabolic risk.
- The relationship between IEV and CMD, specifically whether IEV precedes CMD, requires further elucidation.
Purpose of the Study:
- To determine if functional and/or structural impairment of flow-mediated epicardial vasodilation (IEV) can occur before the development of coronary microvascular dysfunction (CMD).
- To analyze these conditions within a population characterized by cardiometabolic risk factors.
Main Methods:
- Utilized 13N-ammonia positron emission tomography/computed tomography (PET/CT) to assess global and longitudinal myocardial blood flow (MBF) at rest and during hyperemia.
- Defined normal coronary microvascular function (nCMF) with a myocardial flow reserve (MFR) ≥ 2.0 and classical CMD with MFR < 2.0.
- Defined normal flow-mediated epicardial vasodilation (NEV) by a longitudinal hyperemic MBF gradient < -0.10 mL/g/min and IEV by a gradient ≥ -0.10 mL/g/min.
- Coronary artery calcification score (CCS) was assessed using CT.
Main Results:
- Impairment of flow-mediated epicardial vasodilation (IEV) was observed in 60% of the study population.
- The prevalence of IEV was comparable between patients with normal coronary microvascular function and those with CMD (34% vs 46%).
- The hyperemic MBF gradient was significantly lower in patients with IEV compared to those with NEV, indicating impaired vasodilation.
Conclusions:
- In symptomatic patients with cardiometabolic risk, impaired flow-mediated epicardial vasodilation may precede the onset of coronary microvascular dysfunction.
- Approximately one-third of these patients exhibited IEV before the development of CMD, highlighting its potential role as an early indicator.
