Validation of predictors of successful weaning from mechanical circulatory support and histological features in lymphocytic fulminant myocarditis

OBJECTIVE: To validate the prognostic utility of peak creatine kinase-myocardial band isoenzyme (CK-MB) level, left ventricular posterior wall diameter (LVPWD), and a score model for successful weaning from mechanical circulatory support (MCS) in fulminant myocarditis (FM). Furthermore, the severity of the histological data was stratified, and its relationship with the clinical findings was investigated. METHODS: This retrospective single-centre cohort study included 20 patients with FM treated with MCS between 2013 and 2023. The primary outcome was successful weaning from MCS (MCS decannulation and survival to discharge). Two validations were conducted: Validation A, to evaluate the predictive value of peak CK-MB and LVPWD, and validation B, to evaluate the performance of the prediction model for successful MCS weaning derived from the CHANGE PUMP Study. The histological findings of 21 specimens were used for additional analyses. The pathological severity of myocardial inflammation, necrosis and oedema was stratified, and their relationship with clinical data was assessed. RESULTS: 14 patients were successfully weaned from MCS. In validation A, the weaning success rate was significantly higher in patients with peak CK-MB≤185 IU/L than in those with peak CK-MB>185 IU/L. Similar findings were observed in patients with LVPWD≤11 mm compared with those with LVPWD>11 mm. In Validation B, the median predictive MCS weaning success rate for the entire cohort was 80%. Compared with patients who underwent MCS decannulation successfully, those who did not had a significantly lower predictive success rate. The C-statistic of the model was 0.845. The histological severity at admission was not associated with the primary outcome. However, the CK-MB levels and left ventricular ejection fraction (LVEF) obtained simultaneously were correlated with histological severity. CONCLUSIONS: Previously reported predictors of successful weaning from MCS in FM demonstrated reasonable discrimination. The severity of FM evaluated by histological findings was associated with CK-MB levels and LVEF.