MYTHS-MR Trial (MYocarditis THerapy With Steroids in Patients With Mildly Reduced Ejection Fraction)

The goal of this clinical trial is to demonstrate the efficacy of pulsed intravenous methylprednisolone in a single-blind randomized controlled trial versus standard therapy in patients with acute myocarditis and a mildly reduced LVEF. The main question\[s\] it aims to answer are: * is there an increase in LVEF (≥55% or an absolute increase in LVEF ≥ 10%) on echocardiogram after 5 days from randomization in patients treated with pulsed corticosteroid therapy vs. standard therapy? * is there a reduction in the proportion of patients with LVEF \< 55% AND/OR LV dilation on a 6-month CMRI in patients treated pulsed corticosteroid therapy vs. standard therapy? * To assess the effect of corticosteroids on the occurrence of the combined endpoint(1) all-cause death or (2) HTx or (3) long-term LVAD implant or (4) first rehospitalization due to HF or ventricular arrhythmias, or advanced AV block. Participants will be randomized in two arms in a 1:1 ratio. The experimental group will receive pulsed corticosteroid therapy on top of the standard therapy and patients in the placebo group will be treated with a saline solution on top of their standard therapy. All other tests are executed according to standard of care.