Abstract 16260: Children With Increased Native T1, Extracellular Volume and T2 Values on Initial Cardiac Magnetic Resonance Imaging for Acute Myocarditis Have Less Improvement in Late Gadolinium Enhancement on Follow Up Imaging: Risk Factor for Adver

Introduction: Late gadolinium enhancement (LGE) in pediatric patients with acute myocarditis has been shown to be a risk factor for adverse events. On follow up cardiac magnetic resonance imaging (CMR), some patients show improvement and/or resolution of LGE but others do not. Factors associated with residual LGE have not been described.

Hypothesis: Measurements on initial CMR would be associated with degree of improvement of LGE on follow up CMR.

Methods: We conducted a retrospective cohort study of patients <21 years with acute myocarditis who underwent initial CMR within 14 days of presentation and returned for follow up CMR. Those who suffered cardiac arrest or with autoimmune disease, known cardiomyopathy or congenital heart disease were excluded. LGE was defined as tissue with signal intensity 5 standard deviations above mean signal intensity of unaffected myocardium on viability imaging; this mass was measured and indexed to total left ventricular mass. Strain was measured using CMR feature tracking. Spearman’s correlation was used to determine associations between change in indexed LGE mass on follow up CMR to values from initial CMR.

Results: We enrolled 36 patients aged 16.4 years (IQR 14.9-17.2 years) with median time to follow up CMR 229 days (IQR 171, 407). Native T1 (Figure 1), T2, peak T2 relaxation times and ECV on initial CMR inversely correlated with

in indexed LGE mass on follow up CMR while indexed right ventricular end diastolic volume (RVEDVi) on initial CMR positively correlated. (Table 1) Strain and ventricular function did not correlate with change in LGE mass on follow up CMR.

Conclusions: Elevated T1 and T2 values and ECV on initial CMR in patients with acute myocarditis are associated with less improvement of LGE on follow up CMR; increased RVEDVi was associated with greater improvement. Further work is needed to determine which are the most useful predictors of residual LGE following myocarditis in children.