Advances in Multi-Modality Imaging in Hypertrophic Cardiomyopathy

Abstract

Hypertrophic cardiomyopathy (HCM) is characterized by abnormal growth of the myocardium with myofilament disarray and myocardial hyper-contractility, leading to left ventricular hypertrophy and fibrosis. Where culprit genes are identified, they typically relate to cardiomyocyte sarcomere structure and function. Multi-modality imaging plays a crucial role in the diagnosis, monitoring, and risk stratification of HCM, as well as in screening those at risk. Following the recent publication of the first European Society of Cardiology (ESC) cardiomyopathy guidelines, we build on previous reviews and explore the roles of electrocardiography, echocardiography, cardiac magnetic resonance (CMR), cardiac computed tomography (CT), and nuclear imaging. We examine each modality's strengths along with their limitations in turn, and discuss how they can be used in isolation, or in combination, to facilitate a personalized approach to patient care, as well as providing key information and robust safety and efficacy evidence within new areas of research.

Keywords: cardiac computed tomography; cardiac magnetic resonance imaging; echocardiography; hypertrophic cardiomyopathy; multi-modality imaging; nuclear imaging.

Figure 1

Cardiac sarcomere components and corresponding genes, and main imaging modalities with examples of their utility. ACTC1: α actin, CRISP3: Cysteine−rich secretory protein 3, HCM: Hypertrophic cardiomyopathy, MYBPC3: Cardiac myosin−binding protein C3, MYH7: Myosin heavy chain 7, MYL2: Myosin light chain−2, MYL3: Myosin light chain3, MYZO2: Myozenin 2 (calsarcin 1), TNNC1: Troponin C1, TNNI3: Troponin I3, TNNT2: Troponin T2, TPM1: Tropomyosin 1.

Figure 2

Patterns of left ventricular hypertrophy in hypertrophic cardiomyopathy with cardiovascular magnetic resonance. (A) Neutral pattern; (B) reverse curve hypertrophy pattern; (C) apical hypertrophy pattern; (D) 4-chamber view of basal septal hypertrophy pattern; (E) 3-chamber view of basal septal hypertrophy pattern.

Figure 3

Left ventricular outflow tract obstruction (LVOT) in hypertrophic cardiomyopathy with transthoracic echocardiogram. (A,B) Systolic anterior movement of anterior mitral valve leaflet on parasternal long axis and M-mode. (C) Colour flow showing LVOT acceleration with associated posteriorly directed mitral regurgitation. (D) Continuous wave Doppler showing typical ‘dagger shape’ Doppler tracing indicating LVOT obstruction.

Figure 4

Hypertrophic cardiomyopathy and HCM phenocopies with tissue characterization assessment using CMR. In HCM, native T1 and ECV can be either normal or mildly elevated with patchy midwall LGE especially seen in hypertrophic regions. LGE at RV insertion points can also be present. In cardiac amyloidosis, native T1 and ECV is significantly elevated with either subendocardial or transmural LGE throughout the myocardium. In Fabry disease, native T1 is typically low with elevated T2 at corresponding LGE areas with typical basal inferolateral LGE.