LEFT VENTRICULAR NONCOMPACTION CARDIOMYOPATHY: A SCOPING REVIEW

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O.S. Ogah^1,2, E.P. Iyawe³, K.F. Okwunze³, C.A. Nwamadiegesi³, F.E. Obiekwe³, M.O. Fabowale², M. Okeke³, O.A. Orimolade², O.V. Olalusi², A. Aje², A. Adebiyi^1,2

1. Department of Medicine, University of Ibadan, Ibadan, Nigeria.
2. Department of Medicine, University College Hospital, Ibadan, Nigeria.
3. Alexander Brown Hall, College of Medicine, University of Ibadan, Nigeria.

Abstract

Introduction: There has been an upsurge in the reporting of cases of Left Ventricular Noncompaction (LVNC) cardiomyopathy in medical literature in the last 35 years due to advances in medical imaging. The condition was first described in 1926 and the first reported case by echocardiography was in 1984. The American Heart Association considers LVNC a primary cardiomyopathy of genetic origin, while the European Society of Cardiology and the World Health Organization grouped it as an unclassified cardiomyopathy. Its variability in terms of genetic profile, phenotypic expression, clinical presentation, and histopathological findings makes it somewhat a variant of other cardiomyopathies.

Case presentation: Patients with LVNC cardiomyopathy may not have any symptoms or may present with ventricular arrhythmias, heart failure, thromboembolism, or sudden death. LVNC cardiomyopathy diagnosis is typically made by echocardiography, although there are higher resolution cardiac imaging techniques. Management will depend on the patient’s clinical presentation. Due to its genetic association, there is a need to screen living relatives once the diagnosis is made in an individual.

Conclusion: The aim of this paper is to review current knowledge on this condition.

Keyword: Non-compaction, Cardiomyopathy, Genetics, Echocardiography

Introduction

Left Ventricular Noncompaction (LVNC) cardiomyopathy, also known as “spongy myocardium” or “zaspopathy,” is a congenital defect in which there is a developmental arrest of the normal compaction process of the myocardium during the first trimester.¹ This leads to the formation of two layers of myocardium: the compacted and noncompacted layer.² There are three prominent features in LVNC: left ventricular trabeculations, deep intertrabecular recesses communicating with the ventricular cavity and a thin compacted epicardial layer. Together, these impair the heart’s ability to pump blood around the body leading to cardiomyopathy.^3–5 The morphological changes are typically seen around the apex and the lateral walls of the myocardium. LVNC can occur as part of a syndromic congenital anomaly^6–8 and can also occur in isolation from other congenital abnormalities.^4,9–11 The disease is associated with high morbidity and mortality due to thromboembolic events, arrhythmias and heart failure.^4,12 In this paper we review current knowledge on this condition.

HISTORICAL PERSPECTIVE
In the past, newborns with spongy myocardium were usually found with other congenital cardiac anomalies.^13,14 In 1984, due to the advent of better imaging modalities such as echocardiography, the first published case of spongy myocardium without associated cardiac anomalies was documented.¹⁵ In this article, it was called “persistence of isolated myocardial sinusoids,” and this term was used for other subsequent cases.¹⁶ Thereafter, Chin et al. proposed the term“isolated non-compaction of the left ventricular myocardium.”¹⁷ Since then, many terms have been used to describe LVNC, including spongy myocardium, honeycomb myocardium, fetal myocardium, noncompaction cardiomyopathy, hypertrabeculation syndrome and left ventricular noncompaction cardiomyopathy. A graphic representation of the history of LVNC is shown in Figure 1.

EPIDEMIOLOGY
There appears to be an increasing prevalence of LVNC; however, this could be attributed to the emergence of better imaging modalities.¹² The true prevalence of LVNC cannot be estimated as results vary greatly depending on the imaging modality used and the population studied. In a 2020 meta-analysis, the prevalence was found to be 1.28% among the population studied using echocardiography, while it was 14.79% among the population assessed with cardiac magnetic resonance imaging.18 In the pediatric population, a prevalence of 0.14-1.3% has been documented using echocardiography. A US study found the prevalence of LVNC to be 9.5% in children while 9.2% was documented in Australia.¹⁹ The prevalence of LVNC is estimated to be between 0.01% and 0.27% of all adult patients referred for echocardiography.^2,20–22 In the general populace, it is between 0.05% and 0.25% per year.^23,24 In the sporadic form, there is no significant difference in the prevalence of LVNC between both sexes.²⁵ LVNC is not very common among whites.²⁶ There seems to be a higher prevalence (about 30%) among black patients presenting with heart failure. A study among African athletes found that up to 15% almost fulfilled the echocardiographic criteria for LVNC.^27,28 Few cases of LVNC in some sub-Saharan African countries such as Djibouti ²⁹, South Africa ^30,31, Gabon³², Cote d’Ivoire³³, and Nigeria^34,35, have been reported in literature. The epidemiology of LVNC is summarized in Table ^1.27,36,37