Age at onset and clinical course of RBM20-mediated cardiomyopathy

Disease-causative variants in RBM20-encoded RNA-binding motif protein 20 cause a severe arrhythmogenic dilated cardiomyopathy (DCM). We aimed to characterize the clinical course of RBM20-mediated DCM in comparison to other familial and non-familial forms of DCM. The Mayo Clinic Genetic Arrhythmogenic Cardiomyopathy (ACM) Registry was used to identify RBM20- and TTNtv-positive individuals. Additionally, patients with idiopathic non-ischemic DCM were included in this study. Ventricular arrhythmic (VA) events were defined as sustained ventricular arrhythmia, sudden cardiac arrest (SCA), or ventricular tachycardia (VT)/ventricular fibrillation (VF)-terminating implantable cardioverter defibrillator (ICD) therapy and advanced heart failure (AHF) events defined as ventricular assist device implantation or heart transplantation. Overall, we identified 43 RBM20- (49% female) and 108 TTNtv- positive individuals (44% female). RBM20 variant-positive individuals were younger at time of diagnosis at 31 years vs. 45 years old for TTNtv-positive individuals (p < 0.0001). Additionally, RBM20 variant-positive individuals were more likely to have a family history of SCA (67% vs. 30%; p < 0.0001) and cardiomyopathy (88% vs. 61%; p = 0.0008). Interestingly, the prevalence of AHF (14% vs. 5%) events was higher in RBM20 variant-positive patients. RBM20 variant-positive individuals had earlier times to both VA (p = 0.007) and AHF (p = 0.0008) events. Findings were similar in comparison to idiopathic DCM. In this single center study, RBM20 patients had an earlier progressing disease with a higher prevalence of advanced heart failure compared with TTNtv patients. RBM20 patients progressed to VA and AHF endpoints earlier.