Histology of the explanted hearts of children transplanted for dilated cardiomyopathy

Paediatric dilated cardiomyopathy with and without endocardial fibroelastosis - a pathological analysis of 89 explants

Heart failure due to dilated cardiomyopathy is a major indication for paediatric cardiac transplantation. Endocardial fibroelastosis is a recognised pathological finding of unknown prognostic significance in paediatric dilated cardiomyopathy. To evaluate the nature of the association between left ventricular endocardial fibroelastosis and paediatric dilated cardiomyopathy, we reviewed surgical pathology reports of dilated cardiomyopathy explants (1986-2016) in order to characterise the pathological findings and to compare and contrast their frequency among four age groups: less than 1 year; 1-5 years; 6-10 years; and greater than 11 years. The 89 explants (47 males and 42 females) were all characterised by increased weight and left ventricular chamber dilatation without increased wall thickness. Ninety-five per cent of the specimens in the two youngest subsets had left ventricular endocardial fibroelastosis. Compared to the oldest age group, recipients aged 1-5 years had a 6-fold increase and those younger than 1 year a 19-fold increase in the odds of observing left ventricular endocardial fibroelastosis. Explants with and without endocardial fibroelastosis were otherwise phenotypically similar. In paediatric dilated cardiomyopathy endocardial fibroelastosis is a very common pathological finding, especially in infants and young children. We propose that the descriptive, clinico-pathological designation "Dilated Cardiomyopathy with Endocardial Fibroelastosis" should be adopted to facilitate future investigation into the potential prognostic/therapeutic significance of left ventricular endocardial fibroelastosis.

Endomyocardial Biopsy in Pediatric Myocarditis and Dilated Cardiomyopathy: A Tool in Search for a Role

Endomyocardial biopsy (EMB) is a well-known diagnostic tool for the investigation and treatment of myocardial diseases and remains the gold standard for the diagnosis of myocarditis. Due to its invasiveness, with a complication rate ranging from 1 to 15%, its role in the diagnostic work-up of pediatric heart failure is not well established. The aim of this review is to define the role of EMB as diagnostic technique in the work up of children presenting with severe left ventricular dysfunction with the support of our center experience.

Focal myocardial fibrosis assessed by late gadolinium enhancement cardiovascular magnetic resonance in children and adolescents with dilated cardiomyopathy

BACKGROUND

Different patterns of late gadolinium enhancement (LGE) including mid-wall fibrosis using cardiovascular magnetic resonance (CMR) have been reported in adult patients presenting with non-ischemic dilated cardiomyopathy (DCM). In these studies, LGE was associated with pronounced LV remodelling and predicted adverse cardiac outcomes. Accordingly, the purpose of our study was to determine the presence and patterns of LGE in children and adolescents with DCM.

METHODS

Patients <18 years of age presenting with severe congestive heart failure who were admitted for evaluation of heart transplantation at our centre underwent CMR examination which consisted of ventricular functional analysis and assessment of LGE for detection of myocardial fibrosis. Ischemic DCM was excluded by coronary angiography, and right ventricular endomyocardial biopsies ruled out acute myocarditis.

RESULTS

Thirty-one patients (mean age 2.1 ± 4.2 years) with severe LV dilatation (mean indexed LVEDV 136 ± 48 ml/m(2)) and LV dysfunction (mean LV-EF 23 ± 8%) were examined. LGE was detected in 5 of the 31 patients (16%) appearing in various patterns characterized as mid-wall (n = 1), focal patchy (n = 1), RV insertion site (n = 1) and transmural (n = 2). Based on histopathological analysis, 4 of the 5 LGE positive patients had lymphocytic myocarditis, whereas one patient was diagnosed with idiopathic DCM.

CONCLUSIONS

In children and adolescents with DCM, focal histologically proven myocardial fibrosis is rarely detected by LGE CMR despite marked LV dilatation and severely depressed LV function. LGE occurred in various patterns and mostly in patients with inflammatory cardiomyopathy. It remains unclear whether myocardial fibrosis in childhood DCM reflects different endogenous repair mechanisms that enable favourable reverse remodelling. Larger trials are needed to assess the prognostic implications of LGE in childhood DCM.

Role of endomyocardial biopsy for children presenting with acute systolic heart failure

Myocarditis, an inflammatory disease of the heart, frequently results from viral infections, postviral immune-mediated responses, or both. It is a common cause of acute-onset systolic heart failure in children. Endomyocardial biopsy (EMB) remains the gold standard for the diagnosis of myocarditis. However, EMB is not performed for most myocarditis cases involving children in the United States. Clinical scenarios in which EMB results added unique prognostic data and guidance to therapy have been defined recently. This review outlines the role of EMB in the diagnosis and management of myocarditis for children presenting with acute-onset systolic heart failure.

Routine performance of endomyocardial biopsy decreases the incidence of orthotopic heart transplant for myocarditis

BACKGROUND

In critically ill children presenting with dilated cardiomyopathy (DCM), the presence of myocarditis predicts an improved chance of myocardial recovery. Noninvasive differentiation of myocarditis from other causes of DCM is difficult. However, sensitivity of endomyocardial biopsy has been questioned.

METHODS

We reviewed clinical, echocardiographic, catheterization, and pathology data from all children admitted to the intensive care unit with DCM undergoing orthotopic heart transplantation since the inception of our transplant program in 1987 and all patients with definitively diagnosed myocarditis presenting since 1996.

RESULTS

Thirty-six patients with DCM underwent orthotopic heart transplantation. Cellular infiltrate was present in 3 of 36 (8.3%) explanted specimens. Pre-transplant biopsy was performed in 81%. No explanted heart demonstrated infiltrates after a negative biopsy. One biopsy was positive with negative explant histology after transplant 6 months later. No patient with biopsy-proven myocarditis died while listed for transplantation. Eleven additional patients with myocarditis did not undergo transplant. Ten have survived and experienced complete (n = 9) or near complete (n = 1) recovery of myocardial function. One patient died shortly after presentation from fulminant myocarditis. The 10 transplant-free survivors could not be easily distinguished from our transplant cohort by clinical features at presentation.

CONCLUSION

The incidence of cellular infiltrate in explanted hearts was significantly lower than that previously reported. Potentially, our aggressive myocarditis diagnostic protocol was useful in therapeutic stratification as a cohort of myocarditis patients avoided transplant and experienced complete recovery of myocardial function despite being difficult to distinguish clinically from our DCM transplant cohort at presentation.