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OBJECTIVES The purpose of this study was to assess the phenotype of Filamin C (FLNC) truncating variants in dilated cardiomyopathy (DCM) and understand the mechanism leading to an arrhythmogenic phenotype. BACKGROUND Mutations in FLNC are known to lead to skeletal myopathies, which may have an associated cardiac component. Recently, the clinical spectrum of FLNC mutations has been recognized to include a cardiac-restricted presentation in the absence of skeletal muscle involvement. METHODS A population of 319 U.S. and European DCM cardiomyopathy families was evaluated using whole-exome and targeted next-generation sequencing. FLNC truncation probands were identified and evaluated by clinical examination, histology, transmission electron microscopy, and immunohistochemistry. RESULTS A total of 13 individuals in 7 families (2.2%) were found to harbor 6 different FLNC truncation variants (2 stopgain, 1 frameshift, and 3 splicing). Of the 13 FLNC truncation carriers, 11 (85%) had either ventricular arrhythmias or sudden cardiac death, and 5 (38%) presented with evidence of right ventricular dilation. Pathology analysis of 2 explanted hearts from affected FLNC truncation carriers showed interstitial fibrosis in the right ventricle and epicardial fibrofatty infiltration in the left ventricle. Ultrastructural findings included occasional disarray of Z-discs within the sarcomere. Immunohistochemistry showed normal plakoglobin signal at cell–cell junctions, but decreased signals for desmoplakin and synapse-associated protein 97 in the myocardium and buccal mucosa. CONCLUSIONS We found FLNC truncating variants, present in 2.2% of DCM families, to be associated with a cardiac-restricted arrhythmogenic DCM phenotype characterized by a high risk of life-threatening ventricular arrhythmias and a pathological cellular phenotype partially overlapping with arrhythmogenic right ventricular cardiomyopathy.

In 'super-responders' to CRT long-term outcome is excellent. However, cardiac events, mainly CRT-D appropriate interventions, can occur despite the persistence of LVEF > 0.50. Early identification of these patients is still an unsolved issue.

BackgroundThe long‐term progression of idiopathic dilated cardiomyopathy (DCM) in pediatric patients compared with adult patients has not been previously characterized. In this study, we compared outcome and long‐term progression of pediatric and adult DCM populations.Methods and ResultsBetween 1988 and 2014, 927 DCM patients were consecutively enrolled. The pediatric population (aged <18 years at enrollment) included 47 participants (5.1%). At presentation, the pediatric population compared with adult patients had a significantly increased occurrence of familial forms (P=0.03), shorter duration of heart failure (P=0.04), lower systolic blood pressure (P=0.01), decreased presence of left bundle‐branch block (P=0.001), and increased left ventricular ejection fraction (P=0.03). Despite these baseline differences, long‐term longitudinal trends of New York Heart Association class III to IV, left ventricular dimensions, left ventricular ejection fraction, and restrictive filling pattern were similar between the 2 populations. Regarding survival analysis, because of the size difference between the 2 populations, we compared the pediatric population with a sample of adult patients randomly matched using the above‐mentioned baseline differences in a 3:1 ratio (141 adult versus 47 pediatric patients). During a median follow‐up of 110 months, survival free from heart transplantation was significantly lower among pediatric patients compared with adults (P<0.001). Furthermore, pediatric age (ie, <18 years) was found to be associated with an increasing risk of both death from pump failure and life‐threatening arrhythmias.ConclusionsDespite the pediatric DCM population having higher baseline left ventricular ejection fraction and similar long‐term echocardiographic progression compared with the adult DCM population, the pediatric DCM patients had worse cardiovascular prognosis.