Abstract Background Patients with RBM20 cardiomyopathy commonly experience malignant arrhythmias, sudden cardiac death (SCD), and progressive heart failure (HF). Objective The aim of this study is to investigate genotype-phenotype correlations, clinical outcomes and causes of death in patients with RBM20-associated cardiomyopathy in a multicenter cohort, combined with an overview of the current literature. Methods This international, multicenter cohort included all patients with cardiomyopathy who had a pathogenic (P) or likely pathogenic (LP) RBM20 variant. For survival and regression analysis, we matched a control group based on sex, age, and presence of left ventricular dysfunction. Additionally, we conducted a literature search on studies investigating RBM20-associated cardiomyopathy. Results Sixty-two patients (45% male) were included in the study, with a mean age of 42 ± 15 years at presentation. Of the LP/P RBM20 variants identified, 9 were novel. Eleven variants were truncating, while the remaining variants consisted of missense and splice-site variants. Patients with a truncating variant who developed HF were on average older at the time of diagnosis compared to patients with missense variants (mean age 62 ± 9 vs. 45 ± 14; p=0.01). After a median follow-up duration of 5.0 [1.0 – 10.5] years, 21 (34%) patients reached the composite endpoint of ventricular arrhythmias (VA), implantable cardioverter-defibrillator therapy, heart transplantation (HTx), left ventricular assist device (LVAD) implantation, or cardiovascular death. Of these, 19 (31%) patients experienced malignant VA (mean age 45 ± 15 years, 63% males). Males were at higher risk for the composite endpoint (log-rank p= 0.02), particularly for VA (log-rank p=0.007). The literature review analyzed 34 studies with a total of 678 patients, of whom 53% were male. In these studies, 123 (24%) patients experienced a VA, 58 (12%) underwent HTx or were treated with LVAD, and 52 (11%) died. Conclusion In this multicenter study the patients carrying a LP/P variant in RBM20 variants had a severe phenotype, with a high incidence of VA, particularly in males. Additionally, this study presents 9 novel DNA variants, of which 8 were truncating, and were mainly observed in older individuals. Finally, we report a lower mortality rate compared to the literature, possibly due to a higher number of heart transplantations performed in our patient cohort.Survival composite endpoint for sex
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