Expression of Lmna-R225X nonsense mutation results in dilated cardiomyopathy and conduction disorders (DCM-CD) in mice: Impact of exercise training.

•Despite high prevalence of LMNA-mutation related premature onset of heart block and/or dilated cardiomyopathy, the pathophysiogy the mutation to the arrhythmic manifestation have yet to be discovered.•In current study, a Lmna-R225X knockin mice model successfully served as a platform for the disease recapitulation and development of drug screening.•We understood that the presentation of heart block phenotype was accompanied by cardiac fibrosis, especially localized at AV node, which impeded electrical propagation.•Progression to DCM phenotype was observed after electrical modeling events from 18 months of age thereafter.•Surprisingly, endurance exercise by swimming seems to alleviate such phenotype.