Novel risk scoring model to assess the need for venoarterial-extracorporeal membrane oxygenation in patients with acute myocarditis

Abstract Background Some patients with acute myocarditis unpredictably deteriorate into a fulminant form and their prognosis is poor. However, it is uncertain which acute myocarditis patients are likely to exacerbate and even require venoarterial-extracorporeal membrane oxygenation (VA-ECMO). Objectives This study aimed to identify the risk factors associated with the need for VA-ECMO in patients with acute myocarditis and to develop a predictive model. Methods This retrospective study included 841 patients from seven hospitals in Korea with biopsy-proven or clinically suspected acute myocarditis. Logistic regression was performed to identify clinical characteristics of patients who required VA-ECMO and to construct a scoring system that can predict the need for VA-ECMO. Results 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 <65mmHg, cardiac arrest, Glasgow Coma Scale ≤12, platelet <100×103/mL, pulmonary congestion on chest X-ray, QRS interval ≥120ms, 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. The VA-ECMO insertion rate increased with increasing KAM score (odds ratio 1.683, 95% confidence interval 1.529-1.853, P<0.001). 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). Furthermore, at a KAM score of 8 or higher, which was the cut-off KAM score to predict the need for VA-ECMO, patients without VA-ECMO tended to have higher in-hospital mortality than patients who needed VA-ECMO. Conclusions A risk scoring system based on simple clinical and laboratory parameters at initial presentation could predict the need for VA-ECMO and clinical course in patients with acute myocarditis.Graphic Abstract