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Oxygenation-sensitive Cardiac MRI with Vasoactive Breathing Maneuvers for the Non-invasive Assessment of Coronary Microvascular Dysfunction
Published on: August 17, 2022
Myocardial Vascular Function Assessed by Dynamic Oxygenation-sensitive Cardiac Magnetic Resonance Imaging Long-term
Nadia Iannino1, Kady Fischer1,2,3, Matthias Friedrich1,3
1Research Center, Montreal Heart Institute and Université de Montréal, Montreal, QC, Canada.
Insights
Oxygenation-sensitive cardiac magnetic resonance (OS-CMR) reveals impaired myocardial oxygenation in heart transplant recipients, even without cardiac allograft vasculopathy (CAV). This noninvasive technique identifies microvascular dysfunction in stable long-term patients.
Area of Science:
- Cardiology
- Medical Imaging
- Transplantation Science
Background:
- Coronary vascular function impacts outcomes in cardiac transplantation (CTx).
- Cardiac allograft vasculopathy (CAV) is a known complication affecting CTx recipients.
- Noninvasive assessment of myocardial vascular response using oxygenation-sensitive cardiac magnetic resonance (OS-CMR) has not been studied in stable, long-term CTx patients.
Purpose of the Study:
- To investigate the myocardial vascular response in stable long-term CTx recipients using OS-CMR.
- To assess if OS-CMR can detect microvascular dysfunction in CTx patients, with or without CAV.
- To correlate OS-CMR findings with indicators of myocardial injury and fibrosis.
Main Methods:
- Prospective recruitment of CTx patients and healthy controls (HC).
- Cardiac magnetic resonance (CMR) study involving hyperventilation followed by voluntary apnea.
- Monitoring OS-sensitive signal intensity changes to quantify myocardial oxygenation response.
- Utilizing T2-weighted imaging, T1 measurements, extracellular volume, and late gadolinium enhancement to assess myocardial injury.
Main Results:
- OS response was significantly attenuated in CTx patients compared to HC.
- Myocardial oxygenation impairment was evident in CTx patients even without CAV.
- A further attenuation of OS response was observed in CTx patients with severe CAV (grades 2-3).
- Inverse correlation found between OS-CMR, ventricular volumes, and diffuse fibrosis (extracellular volume).
Conclusions:
- Heart transplant recipients exhibit impaired myocardial oxygenation, suggesting microvascular dysfunction, even in the absence of CAV.
- OS-CMR is a viable noninvasive method for identifying these abnormalities using simple breathing maneuvers.
- OS-CMR can aid in the early detection and management of microvascular dysfunction post-CTx.
Background:
Coronary vascular function is related to adverse outcomes following cardiac transplantation (CTx) in patients with or without cardiac allograft vasculopathy (CAV). The noninvasive assessment of the myocardial vascular response using oxygenation-sensitive cardiac magnetic resonance (OS-CMR has not been investigated in stable long-term CTx recipients).
Methods:
CTx patients were prospectively recruited to complete a CMR study with a breathing maneuver of hyperventilation followed by a voluntary apnea. Changes in OS-sensitive signal intensity reflecting the myocardial oxygenation response were monitored and expressed as % change in response to these breathing maneuvers. Myocardial injury was further investigated with T2-weighted imaging, native and postcontrast T1 measurements, extracellular volume measurements, and late gadolinium enhancement.
Results:
Forty-six CTx patients with (n = 23) and without (n = 23) CAV, along with 25 healthy controls (HC), were enrolled. The OS response was significantly attenuated in CTx compared with HC at the 30-second time-point into the breath-hold (2.63% ± 4.16% versus 6.40% ± 5.96%; P = 0.010). Compared with HC, OS response was lower in CTx without CAV (2.62% ± 4.60%; P < 0.05), while this response was further attenuated in patients with severe CAV (grades 2-3, -2.24% ± 3.65%). An inverse correlation was observed between OS-CMR, ventricular volumes, and diffuse fibrosis measured by extracellular volume mapping.
Conclusions:
In heart transplant patients, myocardial oxygenation is impaired even in the absence of CAV suggesting microvascular dysfunction. These abnormalities can be identified by oxygenation-sensitive CMR using simple breathing maneuvers.
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