Anatomical-MRI Correlations in Adults and Children with Hypertrophic Cardiomyopathy

Abstract

Hypertrophic Cardiomyopathy (HCM) is the most frequent hereditary cardiovascular disease and the leading cause of sudden cardiac death in young individuals. Advancements in CMR imaging have allowed for earlier identification and more accurate prognosis of HCM. Interventions aimed at slowing or stopping the disease's natural course may be developed in the future. CMR has been validated as a technique with high sensitivity and specificity, very few contraindications, a low risk of side effects, and is overall a good tool to be employed in the management of HCM patients. The goal of this review is to evaluate the magnetic resonance features of HCM, starting with distinct phenotypic variants of the disease and progressing to differential diagnoses of athlete's heart, hypertension, and infiltrative cardiomyopathies. HCM in children has its own section in this review, with possible risk factors that are distinct from those in adults; delayed enhancement in children may play a role in risk stratification in HCM. Finally, a number of teaching points for general cardiologists who recommend CMR for patients with HCM will be presented.

Keywords: apical aneurysm; cardiac MRI; delayed enhancement; hypertrophic cardiomyopathy; interstitial fibrosis; myocyte disarray; sudden cardiac death.

Figure 1

Main anatomical aspects found in hypertrophic cardiomyopathy compared to control. (A) normal heart. (B) HCM LVOTO = Left ventricular outflow tract obstruction; SAM = systolic anterior motion; ASH = asymmetric septal hypertrophy; mLVWT = maximal left ventricular wall thickness; Ao = aorta; PA = pulmonary artery; LA = left atrium; LV = left ventricle; PV = pulmonary veins; RA = right atrium; RV = right ventricle; SVC = superior vena cava; IVC = inferior vena cava.

Figure 2

Left ventricular outflow tract obstruction by the anterior mitral leaflet which is pulled during late systole into the LVOT as a consequence of the Venturi effect. In most cases of HCM, the hypertrophy is mainly seen at the level of the septum. Mitral regurgitation can be present due to the SAM of AML that leads to a gap between the AML and PML (its presence can be established via Doppler). Ao = aorta; PV = pulmonary vein; LA = left atrium; LVIT = left ventricle inflow tract; LVOT = left ventricle outflow tract; RV = right ventricle; MR = mitral regurgitation; mLVWT = maximal Left ventricular wall thickness; LVOTO = Left ventricular outflow tract obstruction; SAM = Systolic anterior motion; AML = anterior mitral leaflet; PML = posterior mitral leaflet.

Figure 3

Anatomical types of HCM in function of the distribution of hypertrophy.

Figure 4

Cardiac magnetic resonance findings in a patient with asymmetric basal septal hypertrophy (white arrow). Reproduced with permission from [25]. Copyright 2015 Houston BA et al. (under the Creative Commons Attribution 4.0 License, https://creativecommons.org/licenses/by/4.0/, accessed on 6 February 2022).

Figure 5

CMR imaging in the evaluation of HCM. (A) Four-chamber view shows hypertrophy of the apex and papillary muscle found in a patient with apical variant of HCM. (B) Short-axis view with hypertrophy of the junction between the basal anterior interventricular septum and LV anterior free wall; considered most usual location of hypertrophy in HCM. (C) Apical two-chamber view showing a myocardial crypt (marked with black arrow) at the base of the LV inferior wall. (D) LGE in short-axis view of the same patient from Figure 5B, demonstrating patchy replacement fibrosis, (marked with arrow). Reproduced and adapted with permission from [26]. Copyright 2019 Popa Fotea NM et al. (under the Creative Commons Attribution 4.0 License, https://creativecommons.org/licenses/by/4.0/, accessed on 6 February 2022).

Figure 6

CMR during end-diastole showing different types of HCM. (A) Hypertrophy if the inter ventricular septum (VS), sparing the free wall of the LV (FW); (B) Hypertrophy of the LV free wall in the basal portion and a part of the contiguous anterior interventricular septum, which is the most common area involved in HCM; (C) Important hypertrophy >33 mm of the posterior interventricular septum (marked with an asterisk); (D) Focal HCM localized at the bass of the anterior interventricular septum (marked with arrows); (E) localized HCM at the LV apex (marked with asterisks); (F) segmental HCM with hypertrophy of the basal anterior interventricular septum and anterolateral LV wall (marked with asterisks), separated by normal LV (arrows). Reproduced and adapted with permission from [27]. Copyright 2012 Elsevier, Maron MS et al.

Figure 7

CMR comparison of apical aneurysm formation in mixed Apical HCM (A–C) versus pure Apical HCM (D–F). Long axis images of a patient with mixed Apical HCM during diastole in two chambers (Ai) and four chambers (Aii) views, which in systole show midventricular obstruction but not total cavity obliteration due to apical chamber persistence (Bi,Bii). LGE is found in the apical aneurysm (Ci,Cii). A thinned aneurysmal apex is visible in diastole on 2 (Di) and 4 chamber views in a separate patient with pure apical HCM (Dii). The apical aneurysm (Ei,Eii) becomes visible in systole and contains LGE (Fi,Fii). Reproduced and adapted with permission from [35]. Copyright 2020 Hughes RK et al. (under the Creative Commons Attribution 4.0 License, https://creativecommons.org/licenses/by/4.0/, accessed on 6 February 2022).

Figure 8

Abnormalities of mitral valve and papillary muscles in HCM. (a) Isolated posterior papillary muscle hypertrophy (marked with an arrow) and trabeculations along the anterior wall and apical wall (marked with arrowheads); (b) Bifid anterolateral papillary muscle (marked with arrowheads) and thickening of the basal septum (marked with an asterisk); (c) Four accessory papillary muscles, (marked with arrows), diffuse hypertrophy of the left ventricle and pericardial effusion; (d) Accessory apical muscle bundle (marked with arrowheads) traverse the cavity of the left ventricle from the septal basal wall to the distal part of the LV. Reproduced and adapted with permission from [64]. Copyright 2015 Soler R et al. (under the Creative Commons Attribution 4.0 License, https://creativecommons.org/licenses/by/4.0/, accessed on 6 February 2022).

Figure 9

Findings on cardiac magnetic resonance in patients with: (A) Obstructive HCM with intramural septal LGE (arrows: intramural septal LGE). (B) HCM with restricted physiology, significant atrial enlargement, and substantial septal fibrosis (arrows: septal fibrosis). (C) Transmural septal LGE with AL amyloidosis (arrow shows septal LGE). (D) Amyloidosis of wtATTR with LGE, especially in the right ventricle and atria (arrows: LGE in both the right ventricle and left and right atrium). (E) Fabry disease; a case of hypertrophic phenotype with subendocardial LGE in the basal lateral region of the left ventricle (arrows: LGE in the left ventricle’s basal lateral region). (F) Fabry disease with moderate hypertrophy and intramural LGE in the left ventricle’s mid-lateral segment and apex (arrows: LGE in the left ventricle’s mid-lateral segment and apex). Reproduced and adapted with permission from [73]. Copyright 2021 Vio R et al. (under the Creative Commons Attribution 4.0 License, https://creativecommons.org/licenses/by/4.0/, accessed on 6 February 2022).