Abstract
Mutations in filamin-C (FLNC) are involved in the pathogenesis of arrhythmogenic cardiomyopathy (ACM) and dilated cardiomyopathy (DCM), and have been associated with a left ventricular (LV) phenotype, characterized by nonischemic LV fibrosis, ventricular arrhythmias, and sudden cardiac death (SCD). The purpose of this study was to investigate the prevalence of FLNC variants in a gene-negative ACM population and to evaluate the clinical phenotype and SCD risk factors in FLNC-associated cardiomyopathies. ACM probands who tested negative for mutations in ACM-related genes underwent FLNC genetic screening. Clinical and genetic data were collected and pooled together with those of previously published FLNC-ACM and FLNC-DCM patients. In a cohort of 270 gene-elusive ACM probands, 12 (4.4%) had FLNC variants, and 13 additional family members carried the same mutation. Eighteen FLNC variant carriers (72%) had a diagnosis of ACM (72% male; mean age 45 years). On pooled analysis, 145 patients with FLNC-associated cardiomyopathies were included. Electrocardiographic (ECG) low QRS voltages were detected in 37%, and T-wave inversion (TWI) in inferolateral/lateral leads in 24%. Among 67 patients who had cardiac magnetic resonance (CMR), LV nonischemic late gadolinium enhancement (LGE) was found in 75%. SCD occurred in 28 patients (19%), 15 of whom showed LV nonischemic LGE/fibrosis. Compared with patients with no SCD, those who experienced SCD more frequently had inferolateral/lateral TWI (P = .013) and LV LGE/fibrosis (P = .033). Clinical phenotype of FLNC cardiomyopathies is characterized by late-onset presentation and typical ECG and CMR features. SCD is associated with the presence of LV LGE/fibrosis but not with severe LV systolic dysfunction.
Highlights
Arrhythmogenic cardiomyopathy (ACM) is a rare inherited heart muscle disease characterized by myocardial scar, systolic right ventricular (RV) and/or left ventricular (LV)dysfunction, and malignant ventricular arrhythmias (VAs).[1,2,3] The hallmark of ACM is the replacement of ventricular myocardium by fibrofatty tissue, which progresses over time.[1,2,3] Approximately one-half of ACM patients harbor genetic variants in genes encoding major components of the cardiac desmosomes, mutations in nondesmosomal genes have been described in association with ACM.[3,4] Among them, mutations in gene
Two hundred seventy gene-elusive ACM index cases with genetic testing detected 12 FLNC rare variants (4.4%) (Table 1), including 7 “radical” variants (4 deletions/ insertions, 2 nonsense and 1 splice site variants) classified as pathogenic/likely pathogenic (P/LP), and 5 missense variants classified as variants of unknown significance according to American College of Medical Genetics and Genomics recommendations
(3) The clinical phenotype of patients with FLNC-associated cardiomyopathy was characterized by ECG abnormalities such as low QRS voltages and inferolateral/lateral T-wave inversion (TWI), frequent and complex VAs, and extensive nonischemic LV late gadolinium enhancement (LGE)/myocardial fibrosis on cardiac magnetic resonance (CMR) or postmortem analysis
Summary
Arrhythmogenic cardiomyopathy (ACM) is a rare inherited heart muscle disease characterized by myocardial scar, systolic right ventricular (RV) and/or left ventricular (LV). Dysfunction, and malignant ventricular arrhythmias (VAs).[1,2,3] The hallmark of ACM is the replacement of ventricular myocardium by fibrofatty tissue, which progresses over time.[1,2,3] Approximately one-half of ACM patients harbor genetic variants in genes encoding major components of the cardiac desmosomes, mutations in nondesmosomal genes have been described in association with ACM.[3,4] Among them, mutations in gene. Mutations in filamin-C (FLNC) are involved in the pathogenesis of arrhythmogenic cardiomyopathy (ACM) and dilated cardiomyopathy (DCM), and have been associated with a left ventricular (LV) phenotype, characterized by nonischemic LV fibrosis, ventricular arrhythmias, and sudden cardiac death (SCD)
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