LMNA and sick sinus syndrome: In summary, this study describes a novel cardiac phenotype caused by a newly identified pathogenic variant in LMNA gene (c.1526del p.P509Lfs*39) in a large family, where affected family members were clinically characterized by a giant right atrium, sick sinus syndrome, atrial/ventricular arrhythmia with progressive loss of atrial electric activity to atrial standstill, and potential accompanying bicuspid aortic valve malformation.