Genetic Spectrum of Arrhythmogenic Cardiomyopathy

Multidisciplinary approach in cardiomyopathies: From genetics to advanced imaging

Cardiomyopathies are myocardial diseases characterized by mechanical and electrical dysfunction of the heart muscle which could lead to heart failure and life-threatening arrhythmias. Certainly, an accurate anamnesis, a meticulous physical examination, and an ECG are cornerstones in raising the diagnostic suspicion. However, cardiovascular imaging techniques are indispensable to diagnose a specific cardiomyopathy, to stratify the risk related to the disease and even to track the response to the therapy. Echocardiography is often the first exam that the patient undergoes, because of its non-invasiveness, wide availability, and cost-effectiveness. Cardiac magnetic resonance imaging allows to integrate and implement the information obtained with the echography. Furthermore, cardiomyopathies' genetic basis has been investigated over the years and the list of genetic mutations deemed potentially pathogenic is expected to grow further. The aim of this review is to show echocardiographic, cardiac magnetic resonance imaging, and genetic features of several cardiomyopathies: dilated cardiomyopathy (DMC), hypertrophic cardiomyopathy (HCM), arrhythmogenic cardiomyopathy (ACM), left ventricular noncompaction cardiomyopathy (LVNC), myocarditis, and takotsubo cardiomyopathy.

Recent Non-Invasive Parameters to Identify Subjects at High Risk of Sudden Cardiac Death

Cardiovascular diseases remain among the leading causes of death worldwide and sudden cardiac death (SCD) accounts for ~25% of these deaths. Despite its epidemiologic relevance, there are very few diagnostic strategies available useful to prevent SCD mainly focused on patients already affected by specific cardiovascular diseases. Unfortunately, most of these parameters exhibit poor positive predictive accuracy. Moreover, there is also a need to identify parameters to stratify the risk of SCD among otherwise healthy subjects. This review aims to provide an update on the most relevant non-invasive diagnostic features to identify patients at higher risk of developing malignant ventricular arrhythmias and SCD.

Malignant Arrhythmogenic Role Associated with RBM20: A Comprehensive Interpretation Focused on a Personalized Approach

The RBM20 gene encodes the muscle-specific splicing factor RNA-binding motif 20, a regulator of heart-specific alternative splicing. Nearly 40 potentially deleterious variants in RBM20 have been reported in the last ten years, being found to be associated with highly arrhythmogenic events in familial dilated cardiomyopathy. Frequently, malignant arrhythmias can be a primary manifestation of disease. The early recognition of arrhythmic genotypes is crucial in avoiding lethal episodes, as it may have an impact on the adoption of personalized preventive measures. Our study performs a comprehensive update of data concerning rare variants in RBM20 that are associated with malignant arrhythmogenic phenotypes with a focus on personalized medicine.

Dysregulated ribonucleoprotein granules promote cardiomyopathy in RBM20 gene-edited pigs

Ribonucleoprotein (RNP) granules are biomolecular condensates-liquid-liquid phase-separated droplets that organize and manage messenger RNA metabolism, cell signaling, biopolymer assembly, biochemical reactions and stress granule responses to cellular adversity. Dysregulated RNP granules drive neuromuscular degenerative disease but have not previously been linked to heart failure. By exploring the molecular basis of congenital dilated cardiomyopathy (DCM) in genome-edited pigs homozygous for an RBM20 allele encoding the pathogenic R636S variant of human RNA-binding motif protein-20 (RBM20), we discovered that RNP granules accumulated abnormally in the sarcoplasm, and we confirmed this finding in myocardium and reprogrammed cardiomyocytes from patients with DCM carrying the R636S allele. Dysregulated sarcoplasmic RBM20 RNP granules displayed liquid-like material properties, docked at precisely spaced intervals along cytoskeletal elements, promoted phase partitioning of cardiac biomolecules and fused with stress granules. Our results link dysregulated RNP granules to myocardial cellular pathobiology and heart failure in gene-edited pigs and patients with DCM caused by RBM20 mutation.