ADRB2 and myocarditis: Our small number of myocarditis sera limits the study, and further investigation of larger cohorts will be important to broadly assess the prognostic value of CM/βAR AAbs for poor outcomes, and if the mechanism of CM/βAR autoantibody pathogenesis is direct induction of fibrosis in the heart via stimulation of fibroblasts as suggested in our present report, or other mechanisms.