Temporary mechanical support in fulminant myocarditis: prognostic factors and clinical implications from the FULLMOON study

Intensive Care Medicine | Published: 12 January 2026

Background

Temporary mechanical circulatory support (t-MCS) is increasingly used in fulminant myocarditis (FM), yet long-term outcomes and risk factors remain poorly defined.

Methods

From the FULLMOON international cohort (419 adults with suspected FM across 36 centers in 15 countries), 295 patients treated with venoarterial extracorporeal membrane oxygenation (V-A ECMO) and/or Impella were analyzed. The primary endpoint was mortality at 1 year, heart transplantation (HTx), or left-ventricular assist device (LVAD). Multivariate Cox regression identified predictors of adverse outcomes. A propensity score-weighted analysis assessed outcomes based on timing of endomyocardial biopsy (EMB): early (≤ 2 days), delayed (> 2 days), or none.

Results

The median age was 39 years (IQR 28–60), and 55% were female. Myocarditis was confirmed in 204 (69%) of the patients via histology or cardiac MRI. Histological data were available for 151 (51%) of the cohort. One-year mortality was 36%, while 44% died or had an HTx or LVAD. Predictors of worse outcomes were giant cell myocarditis, older age, cardiac arrest at ECMO initiation, and delayed EMB. Delayed EMB was consistently associated with higher mortality, HTx, or LVAD compared to early (HR = 1.55; 95% CI 1.23–1.96; p < 0.01) or no EMB (HR = 1.59; 95% CI 1.26–2.01; p < 0.01). However, event-free survival did not differ significantly between early EMB and no EMB (HR = 1.03; 95% CI 0.80–1.32; p = 0.85).

Conclusions

Despite a relatively young cohort, FM requiring t-MCS is associated with a high 1-year mortality rate. Timely recognition and early referral to specialized ECMO centers before cardiac arrest are critical.

 

Diagnostic yield, safety and therapeutic consequences of myocardial biopsy in clinically suspected fulminant myocarditis unweanable from mechanical circulatory support

 

by Yann Marquet, Guillaume Hékimian, Guillaume Lebreton, Mathieu Kerneis, Philippe Rouvier, Pierre Bay, Alexis Mathian, Nicolas Bréchot, Juliette Chommeloux, Matthieu Petit, Melchior Gautier, Lucie Lefevre, Ouriel Saura, David Levy, Paul Quentric, Quentin Moyon…

 

Annals of Intensive Care volume 13, Article number: 78 (2023)

 

Background

Fulminant myocarditis is a rare and severe disease whose definite and etiological diagnoses rely on pathological examination. Albeit, myocardial biopsy can be associated with significant morbidity and mortality, its therapeutic consequences are unclear. We conducted a study to determine the diagnostic yield, the safety and the therapeutic consequences of myocardial biopsy in patients with fulminant clinically suspected myocarditis unweanable from mechanical circulatory support (MCS).

Methods

Monocenter, retrospective, observational cohort study in a 26-bed French tertiary ICU between January 2002 and February 2019. Inclusion of all fulminant clinically suspected myocarditis patients undergoing in-ICU myocardial biopsy while being on MCS. The primary endpoint was the proportion of patients classified as definite myocarditis using Bonaca criteria before and after including myocardial biopsy results.

Results

Forty-seven patients (median age 41 [30–47], female 53%) were included: 55% died before hospital discharge, 34% could be bridged-to-recovery and 15% bridged-to-transplant. Myocardial biopsy was endomyocardial or surgical in 36% and 64% cases respectively. Tamponade requiring emergency pericardiocentesis occurred in 29% patients after endomyocardial biopsy. After adding the biopsy results in the Bonaca classification algorithm the percentage of definite myocarditis raised from 13 to 55% (p < 0.0001). The rate of biopsy-related treatments modifications was 13%, leading to patients’ recovery in only 4% patients.

Conclusions

In clinically suspected myocarditis unweanable from MCS, myocardial biopsy increased the rate of definite myocarditis but was associated with a low rate of treatment modification and a significant proportion of adverse events. We believe the benefit/risk ratio of myocardial biopsy should be more carefully weighted in these frail and selected patients than suggested by actual guidelines. Further prospective studies are now needed to determine its value in patients under MCS.