Abstract 4146764: Arrhythmia and Left Ventricular Functional Recovery in Arrhythmic Myocarditis Following Immunosuppressive Therapy

Introduction: Treatment of myocarditis often revolves around symptomatic management until recovery. Immunosuppressive therapy (IST) is an option in a select group of patients but is poorly understood. Research Questions: Is there a benefit to IST in myocarditis? Goals: To evaluate the role of IST on ventricular arrhythmia burden and left ventricular ejection fraction (LVEF). Methods: The MAVERIC registry is a prospective, single-center, observational study of patients with a high burden of cardiac arrhythmias and suspected myocarditis. All enrolled patients underwent 18-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging. If positive, patients were managed with IST and guideline-directed therapy. IST consisted of 3 months of Methotrexate and Prednisone, and Folic Acid. A repeat FDG-PET was performed after IST. If persistent inflammation was seen, IST was repeated. We analyzed select baseline characteristics and outcomes. Results: Out of 431 total, 31% had evidence of active myocarditis on FDG-PET and underwent at least one cycle of IST. A further 33.8% underwent a second, 18.8% a third, and 12.0% a fourth cycle of IST for persistent symptoms or FDG-PET. Myocarditis resolved in 64% after one cycle, but 31% of all cases had a relapse requiring further IST. Though incidence of ventricular arrhythmias and LVEF was no different, those with four cycles had significantly higher PVC burden (9.5% vs. 7.0%, p<0.001). LVEF recovery was significant in all groups and greatest in those with multiple cycles of IST (Figure 1). There was no difference in arrhythmia recurrence or implantable cardioverter defibrillator (ICD) needs after treatment. Conclusions: Relapses of myocarditis are common. IST is an important adjunctive strategy in treating arrhythmic, FDG-PET-positive myocarditis and assist LVEF recovery and result in no difference in arrhythmias or ICD needs afterward.