Biventricular noncompaction cardiomyopathy with severe dilated phenotype in a family with a novel MYH7 gene variant

Abstract

Left ventricular noncompaction (LVNC) is a primary genetic cardiomyopathy characterized by abnormal trabeculations frequently seen towards the left ventricular apex. It is heterogeneous in nature and it may present as a single condition, or in combination with other primary cardiomyopathies. Although “left ventricular noncompaction” refers directly to the most commonly involved ventricle, other nomenclature includes “spongy myocardium," “fetal myocardium," and “noncompaction cardiomyopathy," the latter of which most appropriately includes biventricular phenotypes. A frequent sub-phenotype associated with left ventricular noncompaction includes the presence of a dilated left ventricle with decreased function, similar to characteristics of dilated cardiomyopathy. The genetic basis of noncompaction cardiomyopathy has been linked to multiple gene variants and chromosomal anomalies. Here, we present evidence of two first-degree family members (mother and daughter) harboring a novel MYH7 pathogenic gene variant associated with biventricular noncompaction cardiomyopathy with dilated sub-phenotype. Both patients developed end-stage heart failure requiring transplantation. Left ventricular noncompaction isolated/benign phenotype is the most common presentation, yet when it is associated with a dilated phenotype, progressive heart failure may be the inevitable outcome despite medical therapy. In this case report, we describe a novel MYH7 variant (p.Glu1914Lys) linked to biventricular noncompaction and dilated sub-phenotype and congenital heart disease. This case adds to limited information regarding the aggressive phenotype from this pathogenic variant. Based on our report, we encourage clinicians to incorporate genetic testing in patients with noncompaction cardiomyopathy to further stratify this disease and to facilitate cascade genetic testing to relatives at increased cardiovascular risk. Learning objectiveClinicians should become familiar with the recently classified cardiomyopathy, left ventricular noncompaction, also known as noncompaction cardiomyopathy. This includes its array of presenting phenotypes, its criteria for diagnosis, and the most commonly affected genes. Cardiologists should be able to counsel to biological first-degree relatives pertaining to genetic testing, family planning, and the possibility of transplantation in affected individuals. This report provides an example of how familial genetic and phenotypic characterization should influence management in the setting of noncompaction cardiomyopathy.