Contemporary Care and Outcomes of Critically-ill Children With Clinically Diagnosed Myocarditis

Purpose: To describe contemporary management and outcomes in children with myocarditis who are admitted to a cardiac intensive care unit (CICU) and to identify the characteristics associated with mortality.

Methods: All patients in the Pediatric Cardiac Critical Care Consortium (PC⁴) registry between August 2014 and June 2021 who were diagnosed with myocarditis were included. Univariable analyses and multivariable logistic regression evaluated the factors associated with in-hospital mortality.

Results: There were 847 CICU admissions for myocarditis in 51 centers. The median age was 12 years (IQR 2.7-16). In-hospital mortality occurred in 53 patients (6.3%), and 60 (7.1%) had cardiac arrest during admission. Mechanical ventilation was required in 339 patients (40%), and mechanical circulatory support (MCS) in 177 (21%); extracorporeal membrane oxygenation (ECMO)-only in 142 (16.7%), ECMO-to-ventricular assist device (VAD) in 20 (2.4%), extracorporeal cardiac resuscitation in 43 (5%), and VAD-only in 15 (1.8%) patients. MCS was associated with in-hospital mortality; 20.3% receiving MCS died compared to 2.5% without MCS (P < 0.001). Mortality rates were similar in ECMO-only, ECMO-to-VAD and VAD-only groups. The median time from CICU admission to ECMO was 2.0 hours (IQR 0-9.4) and to VAD, it was 9.9 days (IQR 6.3-16.8). Time to MCS was not associated with mortality. In multivariable modeling of patients' characteristics, smaller body surface area (BSA) and low eGFR were independently associated with mortality, and after including critical therapies, mechanical ventilation and ECMO were independent predictors of mortality.

Conclusion: This contemporary cohort of children admitted to CICUs with myocarditis commonly received high-resource therapies; however, most patients survived to hospital discharge and rarely received VAD. Smaller patient size, acute kidney injury and receipt of mechanical ventilation or ECMO were independently associated with mortality.