Atrioventricular Block in the Setting of Immune Myocarditis: A Pragmatic Approach to Diagnosis and Treatment

Immunotherapy has revolutionized cancer treatment in the last decade and has significantly improved patient survival. However, immunotherapy is associated with serious cardiac adverse events including myocarditis and conduction disturbances. In the literature, the mortality rate in patients with immunotherapy-associated myocarditis and complete AV block is reported to be approximately 60%. Current cardio-oncology guidelines provide a series of recommendations for the management of immune myocarditis (IM). However, there is no recommendation on whether or when pacemaker implantation should be performed in the setting of complete AV block associated with myocarditis. This gap in the literature has led to a trend in cardio-oncology practice to implant permanent pacemakers (PPMs) in a significant proportion of patients without waiting for a response to immunosuppressive therapy. However, in a significant proportion of patients undergoing PPM implantation, complete AV block resolves after immunosuppressive therapy. This suggests that in cases of complete AV block in the setting of IM, more robust clues are needed for PPM implantation. This review aims to present algorithms for the management of myocarditis and complete AV block, one of the most lethal complications of immunotherapy, to help fill this gap in the literature.