Novel Risk Scoring Model to Predict the Implementation of Veno-Arterial Extracorporeal Membrane Oxygenation in Patients With Acute Myocarditis

Background: This study aimed to identify risk factors associated with the implementation of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) in patients with acute myocarditis and to develop a predictive model. Methods and Results: This retrospective study included 841 patients from 7 hospitals in Korea with biopsy-proven or clinically suspected acute myocarditis. Logistic regression analysis was used to identify the clinical characteristics of patients who required VA-ECMO and to construct a scoring system to predict the implementation of VA-ECMO. Among the study population, 217 (25.8%) patients underwent VA-ECMO. The study population was divided into training (n=621) and testing (n=220) cohorts according to participating center. The final predictive model of VA-ECMO insertion derived from the training cohort included the following: initial mean blood pressure <65 mmHg, cardiac arrest, Glasgow Coma Scale score ≤12, platelet count <100×10³/mL, pulmonary congestion on chest X-ray, QRS interval ≥120 ms, left or right bundle branch block, and left ventricular ejection fraction <40%. Using this predictive model, a β coefficient-weighted Korean Acute Myocarditis (KAM) score was developed. External validation of the predictive model and KAM score using the testing cohort showed excellent discriminant ability (areas under the curve of 0.945 and 0.921, respectively). Conclusions: A risk scoring system based on simple clinical and laboratory parameters at initial presentation could predict the implementation of VA-ECMO and clinical course in patients with acute myocarditis.