Myocardial Disarray and Fibrosis across Hypertrophic Cardiomyopathy Stages Associate with ECG Markers of Arrhythmic Risk

Ashkir Z 1 , Samat AHA 1 , Ariga R 1 , Finnigan L 1 , Jermy S 2 , Akhtar MA 1 Show all authors , Sarto G 1 , Murthy P 1 , Wong B 1 , Cassar MB 1 , Beyhoff N 1 , Wicks EW 3 , Thomson K 4 , Mahmod M 1 , Tunnicliffe L 1 , Neubauer S 1 , Watkins H 4 , Raman B 1

Affiliations 

  • 1 Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK
  • 2 Cape Universities Body Imaging Centre, Faculty of Health Sciences, University of Cape Town, South Africa; Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Cape Town, South Africa
  • 3 Inherited Cardiac Conditions (ICC) Service, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
  • 4 Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
Eur Heart J Cardiovasc Imaging, 2024 Oct 17.
PMID: 39417278 DOI: 10.1093/ehjci/jeae260

Abstract

BACKGROUND: Myocardial disarray, an early feature of hypertrophic cardiomyopathy (HCM) and a substrate for ventricular arrhythmia, is poorly characterised in prehypertrophic sarcomeric variant carriers (SARC+LVH-).

OBJECTIVES: Using diffusion tensor cardiac magnetic resonance (DT-CMR) we assessed myocardial disarray and fibrosis in both SARC+LVH- and HCM patients and evaluated the relationship between microstructural alterations and electrocardiographic (ECG) parameters associated with arrhythmic risk.

METHODS: Sixty-two individuals (24 SARC+LVH-, 24 HCM and 14 matched controls) were evaluated with multiparametric CMR including stimulated echo acquisition mode (STEAM) DT-CMR, and blinded quantitative 12-lead ECG analysis.

RESULTS: Mean diastolic fractional anisotropy (FA) was reduced in HCM compared to SARC+LVH- and controls (0.49±0.05 vs 0.52±0.04 vs 0.53±0.04, p=0.009), even after adjustment for differences in extracellular volume (ECV) (p=0.038). Both HCM and SARC+LVH- had segments with significantly reduced FA relative to controls (54% vs 25% vs 0%, p=0.002). Multiple repolarization parameters were prolonged in HCM and SARC+LVH-, with corrected JT interval (JTc) being most significant (354±42ms vs 356±26ms vs 314±26ms, p=0.002). Among SARC+LVH-, JTc duration correlated negatively with mean FA (r=-0.6, p=0.002). In HCM, the JTc interval showed a stronger association with ECV (r=0.6 p=0.019) than FA (r=-0.1 p=0.72). JTc discriminated SARC+LVH- from controls (Area-under-the-receiver-operator-curve 0.88, CI 0.76-1.00, p<0.001), and in HCM correlated with the ESC HCM sudden cardiac death risk score (r=0.5, p=0.014).

CONCLUSION: Low diastolic FA, suggestive of myocardial disarray, is present in both SARC+LVH- and HCM. Low FA and raised ECV were associated with repolarization prolongation. Myocardial disarray assessment using DT-CMR and repolarization parameters such as the JTc interval demonstrate significant potential as markers of disease activity in HCM.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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