Abstract 2556: A Comparative Analysis of Outcomes for Pediatric Patients with Biopsy-Proven Myocarditis, Clinically-Diagnosed Myocarditis and Idiopathic Dilated Cardiomyopathy.
Background: Data on outcomes in children with myocarditis is sparse and challenging to interpret given no ``gold standard” for diagnosis. The NHLBI Pediatric Cardiomyopathy Registry provides a large, multi-center cohort with clinical and echocardiographic follow-up of up to 16 years.
Methods/Results: We compared cases of biopsy-confirmed myocarditis (BCM, N=119) and clinically-diagnosed myocarditis (CDM, N=253), with idiopathic dilated cardiomyopathy (IDCM, N=1123). BCM and CDM patients were older at diagnosis than those with IDCM (median age 1.6, 1.9, 1.2 yr, respectively). For BCM, heart failure symptoms (86%) and admission (97%) at diagnosis were more common (p<0.05 compared to either CDM/IDCM). LV end-diastolic dimension (EDD) Z-score was abnormal (>2) in 71% with myocarditis and 86% with IDCM. Systolic function was impaired in all groups, with a median fractional shortening (FS) Z score of -9 for myocarditis and -10 for IDCM; 23% of myocarditis patients had impaired function without dilation. Two-year death/transplant rates were 24% (BCM), 24% (CDM), and 47% (IDCM). Of myocarditis survivors, 46% had normalization of both EDD and FS Z-scores at 2 years vs. 25% for IDCM (p<.0001). Baseline echo status was strongly associated with later echo status for IDCM pts. Recovery from myocarditis at 2 years was not strongly associated with baseline echocardiographic characteristics, but transplant-free survival was lower in myocarditis patients when both baseline FS and EDD were abnormal (logrank p=.03). When therapeutic data were available, the BCM group received IVIG/steroids most often (44% vs. 23% CDM, 6% IDCM); this was not significantly associated with 2-year echo recovery or transplant-free survival, but power was limited.
Conclusions: In this dataset, children with BCM and CDM have similar profiles and a better outcome than those with IDCM, with 76% surviving without transplant at 2 years. Nearly 1/2 have normalization of LV size and function, but the presence of both dilation and poor function at presentation is associated with increased risk for death or transplant. Echocardiographic normalization occurs in 25% of IDCM survivors by 2 years. This study is limited by being an analysis of available information in a database collected for other purposes.