Myocardial Fibrosis in Hypertrophic Cardiomyopathy: Leveraging Quantitative Imaging and Artificial Intelligence for Precision Management

Figures

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  Fig. 1.. Advances in myocardial fibrosis imaging in hypertrophic cardiomyopathy. The figure was created in https://BioRender.com. 2D-STE, two-dimensional speckle tracking echocardiography; SWI, shear wave imaging; CMR, cardiac magnetic resonance; LGE, late gadolinium enhancement; ECV, extracellular volume; PET, positron emission tomography; SPECT, single photon emission computed tomography.

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  Fig. 2.. Pathophysiological mechanisms of myocardial fibrosis in HCM. Mutations in sarcomeric genes are the main culprits for cardiac fibrosis in hypertrophic cardiomyopathy. Cardiac electrophysiological changes, increased myocardial stiffness, myocardial cell hypertrophy, and inflammatory response participate in the formation of myocardial fibrosis in HCM. The figure was created in https://BioRender.com. HCM, hypertrophic cardiomyopathy; MYH, β-myosin heavy chain; MYBPC3, myosin-binding protein C3; TNNI3, cardiac troponin I 3; ACTC1, actin alpha cardiac muscle 1; MYL2/MYL3, myosin light chain 2/3; TPM1, tropomyosin 1; TNNT2, cardiac troponin T2.

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  Fig. 3.. CMR delayed enhancement imaging (LGE-CMR) has demonstrated four typical types of myocardial fibrosis distribution in patients with hypertrophic cardiomyopathy. (A) Apical hypertrophic cardiomyopathy: LGE shows diffuse cloud-like and patchy delayed enhancement from the base to the apical myocardium, with enhancement predominating in the apical portion, suggesting widespread fibrosis. (B) Apical hypertrophic cardiomyopathy with ventricular aneurysm: LGE enhancement is mainly distributed in the mid-segment septum and right ventricular insertion with obvious enhancement of the sub-endocardium of the apical segment and the myocardium of the apical segment, and a ventricular aneurysm is present at the apical segment. (C) Interventricular septal hypertrophic cardiomyopathy: LGE shows multiple patchy delayed enhancements of the myocardium from the basal segment to the middle of the interventricular septum, which is focally striated. (D) Left ventricular diffuse hypertrophic cardiomyopathy: LGE shows multiple segments of the left ventricular myocardium with patchy abnormal enhancement signal shadow. A small area of low signal shadow is seen in the area of enhancement in the…

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  Fig. 4.. T1 mapping and ECV in (A) hypertrophic cardiomyopathy, (B) cardiac amyloidosis, and (C) Fabry disease. (A) This hypertrophic cardiomyopathy (HCM) patient demonstrated a native T1 value of 1351 ± 99 ms and an extracellular volume fraction (ECV) of 36 ± 15%, both of which were mildly elevated compared to normal ranges. Cardiac imaging revealed multiple patchy mid-myocardial late gadolinium enhancement (LGE) distributed from the basal to mid segments of the left ventricle. (B) In cardiac amyloidosis, native T1 and ECV are significantly elevated (1384 ± 61 ms and 65 ± 10%, respectively), with LGE showing diffuse delayed enhancement across multiple myocardial segments, predominantly in a subendocardial distribution and partially transmural in some regions. (C) In Fabry disease, native T1 was elevated (1384 ± 97 ms), with an ECV of 35 ± 24%; LGE was localized to the basal lateral wall of the left ventricle, showing subendocardial delayed enhancement, suggesting focal myocardial fibrosis in the advanced stage. Source: images from our hospital’s cardiovascular surgery department from 2022 to 2024.

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  Fig. 5.. Ultrasound imaging in HCM fibrosis assessment. (A) Non-fibrotic HCM: LGE negative, SWV = 143 cm/s, GLS = –17.8%, normal tissue elasticity, mildly reduced systolic function. (B) Mild fibrosis HCM: LGE positive, focal distribution, SWV = 206 cm/s, GLS = –12.9%, elasticity elevated, strain decreased. (C) Severe fibrosis HCM: LGE positive, extensive distribution, SWV = 310 cm/s, GLS = –5.2%, spasticity significantly elevated, strain severely impaired. Source: images from our hospital’s cardiovascular surgery department from 2022 to 2024. HCM, hypertrophic cardiomyopathy; GLS, global longitudinal strain; LGE, late gadolinium enhancement; SWV, shear wave velocity.