Fulminant Myocarditis with VA-ECMO Support: Clinical Characteristics and Prognosis in a Cohort from a Tertiary Transplant Center

Background/Objectives: Fulminant myocarditis (FM) is an uncommon but potentially reversible form of myocardial inflammation that can rapidly progress to cardiogenic shock (CS). In patients who are refractory to conventional treatment, venoarterial extracorporeal membrane oxygenation (VA-ECMO) represents an effective life support strategy. However, the factors that determine functional recovery remain uncertain. The primary objective of this study was to characterize patients who recover ventricular function. Secondary objectives included analyzing VA-ECMO-related complications and overall patient survival. Methods: This was a retrospective, single-center, observational study including all consecutive patients diagnosed with FM between 2008 and 2025 who were supported with VA-ECMO (n = 22). Clinical, biochemical, echocardiographic, and imaging variables were collected. Patients were classified based on their outcomes as either recovery or death/transplantation. Differential factors potentially affecting myocardial recovery, survival, and complications were analyzed. Results: The mean age was 49.7 ± 11 years, with 36% being male. Severe cardiogenic shock was the most common initial presentation (86%), and the average time from symptom onset to hospital admission was 5.7 days. Regarding mechanical support, the non-recovery group required longer ECMO support (328 ± 225 h vs. 188 ± 103 h; p = 0.03). The presence of fibrosis on cardiac magnetic resonance imaging (MRI) was associated with a lower probability of recovery (100% vs. 44.4%; p = 0.03). Renal failure and vascular complications were more frequent in the non-recovery group, with a significantly higher rate of surgical reintervention (50% vs. 10%; p = 0.04). Echocardiography performed before discharge (recovery group) vs. before death/transplant (non-recovery group) showed significant differences in left ventricular ejection fraction (51.1% vs. 29.5%; p = 0.04), along with better levels of creatinine, N-terminal pro-B-type natriuretic peptide (NT-proBNP), leukocytes, and C-reactive protein (CRP) in the recovery group. In-hospital survival for the entire cohort was 63.6%, significantly higher in the recovery group (100% vs. 33.3%; p < 0.01). One-year survival was 59%, which was also greater among those who recovered (90% vs. 33.3%; p = 0.02). Conclusions: FM is associated with an acceptable in-hospital survival rate. The presence of myocardial fibrosis on MRI and longer ECMO support duration were observed to be associated with a lower likelihood of cardiac recovery. Patients who recovered showed better ventricular function at discharge, as well as reduced systemic inflammation and renal dysfunction. These findings highlight the importance of early identification of predictors of myocardial recovery to optimize management and therapeutic decision making in this high-risk population.