Scar and Edema Imaging by CMR in Pediatric Myocarditis—Preliminary Results from the MYKKE-Registry

Background: CMR provides important diagnostic information in adult acute myocarditis while data in children are scarce. In this study, we sought to determine the prevalence of both late gadolinium enhancement (LGE) of myocardial scar and T2-based detection of myocardial edema (T2) in suspected acute myocarditis.

Method: From the multicenter registry for suspected pediatric myocarditis “MYKKE,” CMR images from 16 centers were analyzed using core-laboratory consensus image reading. Investigations were based on the centers’ own discretion using a standardized protocol enabling volumetric, LGE, and T2 evaluations. Patterns of myocardial scar (LGE) and edema (T2) were assessed from three ventricular short axis slices, as well as four-chamber and two-chamber long-axis views and plotted using a 16-segment AHA model. CMR data were correlated with LGE/T2 presence and outcome parameters.

Results: CMR studies were available in 229 children with suspected myocarditis with a median age of 15 years (25/75% interquartile range, 9–16 years). Severe arrhythmia occurred in 32 patients (14%). Twenty-one patients needed mechanical circulatory support (MCS, 9%), five patients (<1%) received heart transplantation (HTx), and five patients (<1%) died. CMR was performed after a median of 7 days (3–17) after onset of symptoms. The median left ventricular ejection fraction (LVEF) was 61.2% (52.8–67.0) with an indexed median LV end-diastolic diameter (LVEDVi) of 81.8 mL/m² (71.7–94.4). LGE was present in 130/229 patients (57%). In terms of scar load, 86% of these had LGE in >2 segments and 40% in >5 segments. Edema was observed in 73/229 patients (32%). Edema together with LGE was detected in 58 patients (44%). There was no correlation between LVEF/LVEDVi and the number of segments affected by scar (LGE). Correlating age and LVEF/LVEDVi, younger patients showed lower values for both (r = 0.32/0.291). Neither existence nor severity of LGE correlated with the rate of severe arrhythmia, MCS, HTx, or death.

Conclusion: In this ongoing registry, CMR was predominantly available from school-aged/adolescent patients. Although LGE and edema were seen in a large part of the cohort, neither correlated with LVEF or hard outcome criteria, given the mostly preserved LVEF and the overall good outcome in this sample. Future work will need to extend into the younger age group and correlate CMR with myocardial biopsy results, to better define the predictive power of CMR in pediatric acute myocarditis.

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Artikel online veröffentlicht:
12. Februar 2022