Naaraayan A, Meredith A, Nimkar A, et al. - Researchers conducted this retrospective cohort study to evaluate the prevalence of arrhythmia and its subtypes by age and gender in patients with polymyositis–dermatomyositis (PD) and to determine associations between arrhythmia and PD. Adults whose hospitalizations were documented in the National Inpatient Sample database in the United States between 2016 and 2018 were included in the study. Thirty-two thousand eighty-five adults with PD were matched to 320,850 controls from 107,001,355 hospitalizations. When compared with matched controls, young and middle-aged individuals with PD had a higher prevalence and risk of arrhythmias, particularly supraventricular arrhythmias. Arrhythmias were linked to a higher risk of death in PD patients.