BACKGROUND: The clinical spectrum of pediatric acute myocarditis ranges from minimal symptoms with intact hemodynamics to rapid cardiovascular collapse and death. We sought to identify factors on initial presentation associated with subsequent hemodynamic compromise. METHODS: We performed a retrospective cohort study of patients with acute myocarditis at a freestanding pediatric hospital from 2007 to 2016. We defined 2 cohorts: high-acuity patients with hemodynamic compromise defined as requiring inotropic or vasoactive medications, cardiopulmonary resuscitation, extracorporeal membrane oxygenation, ventricular assist devices, or transplant or who died and low-acuity patients without these interventions. We collected the first recorded set of vital signs, symptoms, laboratory values, and chest radiograph, electrocardiogram, and echocardiography results. Univariate analysis was performed, and 2 multivariable logistic regression models were created to discriminate between cohorts. RESULTS: A total of 74 patients were included: 33 high acuity and 41 low acuity. There were significant differences in demographics, symptoms, and physical examination, laboratory, electrocardiogram, and echocardiography findings between high- and low-acuity cohorts. Multivariable logistic regression models were highly discriminate in predicting those in the high-acuity cohort. The first model included presence of tachycardia, tachypnea, creatinine, and cardiomegaly on chest radiograph (area under the curve = 0.913). The second model added the presence of pericardial effusion to the above variables (area under the curve = 0.964). CONCLUSIONS: Models based on factors available at initial presentation with acute myocarditis are predictive of subsequent hemodynamic compromise. If our results can be validated in a multicenter study, these models may help disposition patients with suspected acute myocarditis (with those who meet model criteria being admitted to centers capable of rapidly providing extracorporeal membrane oxygenation, ventricular assist devices, and heart transplant evaluation).