Apical hypertrophic cardiomyopathy

Clinical History

Patient presenting with dyspnoea and oppressive chest pain.
Personal history of arterial hypertension. Normal coronary arteries in angiography. In echocardiography left ventricular hypertrophy, difficult to evaluate due to a poor acoustic window. The patient was referred for a MR examination to evaluate hypertensive or asymmetric hypertrophy of the left ventricle.

Imaging Findings

Marked hypertrophy of the left ventricle (LV) wall involving the apical segments with a maximal wall thickness of 23 mm. Basal segments had a normal wall thickness (9 mm in the septum and 7 mm in the lateral wall).
Moderate thickening of the apical portion of the right ventricle is appreciated in the four chambers view.
In the late enhancement sequence, diffuse and mildly heterogeneous enhancement of the left ventricle wall in the apical (hypertrophied) segments is appreciated.
The LV ejection fraction is normal (65%). Mild mitral regurgitation is seen in the two chambers b-SSFP sequence cine images.

Discussion

Hypertrophic cardiomyopathy (HCM) is one of the most prevalent cardiomyopathies, approximately 1:500. It is a genetic disease related to the sarcomeric structure, involving different genes and proteins, with an autosomic dominant pattern of inheritance and variable penetrance. The histological landmark of the disease is disarray and thickening of the cardiomyocytes, and interstitial fibrosis [1].
Clinical course is usually benign and the vast majority of patients are asymptomatic, but there is a dramatic initial presentation with sudden death, usually in young patients due to arrhythmias during exercise.
Morphological features of the disease include eccentric (asymmetric) wall thickening. The most frequently affected segments being the septum and the anterior wall. Apical involvement is unusual. Thickening of the right ventricle wall can occasionally be seen.
Cardiac Magnetic Resonance (CMR) allows an accurate morphological and functional evaluation with no window restriction. This allows an easier characterisation of atypical locations of HCM. This is the case of the apical form of HCM, because the apex may be difficult to be evaluated in echocardiography due to near-field problems with the echo probe [2].
The apical form of HCM shows thickening (more than 12 mm) of the left ventricle wall, involving mainly the apical segments. It is a highly prevalent form in Japan. Different configurations have been described with involvement of the apex with symmetric or asymmetric middle-basal segments hypertrophy. The classical “spade like” morphology of the left ventricle cavity correlates with pure apical involvement, and it is supposed to be less prevalent in the western countries. The apical HCM form does not include a dynamic left ventricular outflow tract obstruction [3].
Medical treatment is feasible in most of the patients. However, to prevent sudden death, high risk patients need implantation of a defibrillator. Depiction of fibrosis and its extension in late gadolinium enhancement (LGE) MR images is a known risk factor [1].
When late gadolinium enhancement is present in the hypertrophied segments in the HCM, it is related to fibrosis and increased extracellular space in the disarray areas. This is a known low prognostic sign and a risk factor for arrhythmias.
Therefore, aside from the superior multiplanar capability of CMR to evaluate morphological changes in HCM, late gadolinium enhancement images must be added to the MR protocol in order to improve diagnosis and depict the presence of fibrosis, which is an important prognostic factor.

Differential Diagnosis List

Final Diagnosis

Apical hypertrophic cardiomyopathy

URL:	https://www.eurorad.org/case/9792
DOI:	10.1594/EURORAD/CASE.9792
ISSN:	1563-4086