Fulminant acute myocarditis in the cardiac intensive care unit. A long but successful road to recovery

Background and Aim Fulminant myocarditis leading to cardiogenic shock (CS) is a life-threatening condition arising from various inflammatory etiologies. This study aims to describe the clinical characteristics, management and outcomes of patients with myocarditis-related CS treated at a tertiary center with mechanical circulatory support (MCS) capabilities. Methods Retrospective, observational single-center study of consecutive patients (pts) admitted to Cardiac Intensive Care Unit for CS-related myocarditis, between 2018 and 2024. Diagnostic confirmation was made through cardiac magnetic resonance imaging (CMR) or endomyocardial biopsy (EMB), while a presumed diagnosis was considered based on clinical, laboratorial and TTE features in the absence of coronary artery disease. Results Fourteen pts (mean age 45 ± 14 years, 64% male) were included. The majority (93%, n = 13) experienced their first myocarditis episode. The most common symptom at admission was chest pain (57%, n = 8), while 29% (n=4) immediately presented in CS. The median time from initial symptom onset to CS was 5 days (IQR 4–6). Median LVEF at admission was 25 (IQR 20 – 34)%, and biventricular dysfunction was present in 57% (n=8). Diagnosis was confirmed by EMB (diagnostic yield 80%) or CMR in 13 pts, while 1 was diagnosed presumptively. SCAI class at admission was C in 9 pts (64%), D in 4 (29%) and E in1 pt (7%), with 5 pts deteriorating over the first 24 hours. All pts required vasoactive pharmacological support, and 71% (n = 10) required MCS, mostly VA-ECMO (n=9). Other interventions included non-invasive and invasive mechanical ventilation (71%, n=10) and renal replacement therapy (21%, n = 3). Complete AV block occurred in 14% (n = 2) of patients, 21% (n = 3) had ventricular arrythmias and 1 patient (7%) had cardiac tamponade requiring pericardiocentesis. ICU length-of-stay was 12 days (IQR 7 – 21), and total hospital admission was 32 days (IQR 20–47). In-hospital mortality was 14% (n = 2): one due to refractory shock and another for surgical LVAD-related complications. One patient underwent transplantation for unrecovered biventricular failure. Among survivors (n = 11), LVEF improvement was observed at discharge (51 (IQR 41 – 56)%; p < 0.001), with 64% (n = 7) normalizing LVEF (>50%). During a median follow-up of 20 months (IQR 5–35), one patient died of non-cardiovascular causes, and another underwent transplantation for persistent heart failure. The remaining patients (n = 8) were in NYHA class I or II, and all maintaining LVEF >50%. Conclusions Fulminant myocarditis carries significant acute morbidity and mortality and often requires MCS as a bridge-to-recovery. However, survivors demonstrate favorable long-term outcomes, including functional recovery and LVEF normalization. Further studies are needed to optimize support strategies and improve outcomes in this high-risk population.