SCMR/ISMRM Workshop: Oxygen-Sensitive MRI and Perfusion

1343248 - Impaired Stress Myocardial Oxygenation precedes contractile abnormalities in Three Models of Cardiac Hypertrophy: Insights from a Novel Oxygen Sensitive Cardiac Magnetic Resonance Approach.

Wednesday, January 25, 2023

5:00 PM – 6:30 PM

Location: Silver Pearl 1

Presenting Author(s)

MA

Mohammed Akhtar, MD, BSc

Clinical Research Fellow
Oxford Centre for Magnetic Resonance Research, United Kingdom

Primary Author(s)

MA

Mohammed Akhtar, MD, BSc

Clinical Research Fellow
Oxford Centre for Magnetic Resonance Research, United Kingdom

Co-Author(s)

HM

Hasan Mohiaddin

Clinical Research Fellow
Oxford Centre for Magnetic Resonance Research, United Kingdom
Eylem Levelt, PhD

Associate Professor and Honorary Consultant
University of Leeds
Leeds, England, United Kingdom
HW

Hugh Watkins, MD, PhD

Professor of Cardiovascular Medicine
University of Oxford, England, United Kingdom
MM

Masliza Mahmod, MD, PhD

Associate Professor
Oxford Centre for Magnetic Resonance Research, England, United Kingdom
Stefan Neubauer, MD, FSCMR

Professor of Cardiovascular Medicine
University of Oxford
Oxford, England, United Kingdom
Betty Raman, MD, PhD

Associate Professor
University of Oxford
Oxfordshire, England, United Kingdom

Disclosure(s):

Stefan Neubauer, MD, FSCMR: No relevant disclosure to display

Betty Raman, MD, PhD: No financial relationships to disclose

Background: Cardiac hypoxia is a key cause of myocardial dysfunction, but remains under-investigated due to challenges with direct myocardial oxygen assessment. Fast low flip angle short (FLASH) normalised blood-oxygen level-dependent cardiovascular magnetic resonance (nBOLD CMR) is a novel oxygen-sensitive CMR approach which allows for precise measurement of myocardial oxygenation (1).
We sought to a) characterise myocardial oxygenation in three models of hypertrophy: genetic - non-obstructive hypertrophic cardiomyopathy (nHCM); metabolic - Type 2 diabetes (T2DM); structural - severe Aortic Stenosis (SevAS) using nBOLD CMR and b) evaluate its potential for detecting oxygenation impairment in relation to contractile and perfusion abnormalities.

Methods: 113 participants including healthy controls (n=30), T2DM (n=29), nHCM (n=29), and severe AS (n=24) underwent cine, adenosine stress nBOLD CMR, first pass perfusion imaging and late gadolinium (LGE) CMR. Stress oxygenation, absolute myocardial blood flow (MBF) and global longitudinal strain (GLS) were evaluated in all patients.

Results: nHCM and SevAS had significantly thicker and fibrotic myocardium compared to controls and T2DM. Hyperaemic MBF was severely impaired in nHCM and SevAS (nHCM 2.1±0; SevAS 1.7± ml/min/g) relative to controls (3.0±0.9 ml/min/g; p< 0.001), but to a lesser extent in T2DM (T2DM 2.6±0.7 ml/min/g; p=0.03). Stress oxygenation was significantly reduced in T2DM, nHCM and SevAS, with further differences seen between T2DM and nHCM, (CON 17.4±2.1%; T2DM 12.5±4.8%; nHCM 8.34±4.5%; SevAS 9.18±6.5%; p</span>< 0.0001, Fig 1). Among patients, 67% had normal contractility (GLS< -15% and LVEF >52%), and 54% had preserved perfusion (segmental stress MBF >1.4 ml/min/g). Stress oxygenation was impaired even among patients with preserved contractility (p=0.005) and perfusion (p< 0.001) versus controls.

Conclusion: This is the first application of nBOLD CMR in severe AS and T2DM. T2DM had impaired myocardial oxygenation even in the presence of mild/no perfusion abnormalities, consistent with inefficient oxidative metabolism. nHCM and severe AS shared similarly blunted perfusion and oxygenation. Myocardial deoxygenation precedes contractile and perfusion abnormalities in hypertrophied hearts, highlighting the potential for stress BOLD to detect subclinical metabolic and perfusion abnormalities in cardiac diseases.

nBOLD CMR is a promising, precise, and contrast-agent free tool to characterise myocardial oxygenation in a diverse range of cardiovascular diseases with a potential to enhance current diagnostic and prognostic algorithms.