Abstract
BackgroundAdverse fibrotic remodeling is detrimental to myocardial health and a reliable method for monitoring the development of fibrotic remodeling may be desirable during the follow-up of patients after heart transplantation (HTx). Quantification of diffuse myocardial fibrosis with cardiovascular magnetic resonance (CMR) has been increasingly applied and validated histologically in adult patients with heart disease. However, comparisons of CMR findings with histological fibrosis burden in children are lacking. This study aimed to compare native T1 times and extracellular volume fraction (ECV) derived from CMR with the degree of collagen on endomyocardial biopsy (EmBx), and to investigate the association between myocardial fibrosis and clinical as well as functional markers in children after HTx.MethodsEmBx and CMR were performed on the same day. All specimens were stained with picrosirius red. The collagen volume fraction (CVF) was calculated as ratio of stained collagen area to total myocardial area on EmBx. Native T1 values and ECV were measured by CMR on a mid-ventricular short axis slice, using a modified look-locker inversion recovery approach.ResultsTwenty patients (9.9 ± 6.2 years of age; 9 girls) after HTx were prospectively enrolled, at a median of 1.3 years (0.02–12.6 years) post HTx, and compared to 24 controls (13.9 ± 2.6 years of age; 12 girls). The mean histological CVF was 10.0 ± 3.4%. Septal native T1 times and ECV were higher in HTx patients compared to controls (1008 ± 32 ms vs 979 ± 24 ms, p < 0.005 and 0.30 ± 0.03 vs 0.22 ± 0.03, p < 0.0001, respectively). CVF showed a moderate correlation with native T1 (r = 0.53, p < 0.05) as well as ECV (r = 0.46, p < 0.05). Native T1 time, but not ECV and CVF, correlated with ischemia time (r = 0.46, p < 0.05).ConclusionsCMR-derived fibrosis markers correlate with histological degree of fibrosis on EmBx in children after HTx. Further, native T1 times are associated with longer ischemia times.
Highlights
Adverse fibrotic remodeling is detrimental to myocardial health and a reliable method for monitoring the development of fibrotic remodeling may be desirable during the follow-up of patients after heart transplantation (HTx)
We hypothesized that native T1 and extracellular volume fraction (ECV) are associated with the histological degree of fibrosis within the myocardium of pediatric Heart transplantation (HTx) recipients
The organ age which was calculated as the sum of the donor age at demise and the time since HTx, was similar between the two groups. (Table 1) In terms of immunosuppressive medication, at the time of the cardiovascular magnetic resonance (CMR), 16 patients received tacrolimus and mycophenolate mofetil, two tacrolimus and mycophenolate mofetil in addition to prednisone, one tacrolimus monotherapy, and one sirolimus with mycophenolate mofetil
Summary
Adverse fibrotic remodeling is detrimental to myocardial health and a reliable method for monitoring the development of fibrotic remodeling may be desirable during the follow-up of patients after heart transplantation (HTx). Quantification of diffuse myocardial fibrosis with cardiovascular magnetic resonance (CMR) has been increasingly applied and validated histologically in adult patients with heart disease. This study aimed to compare native T1 times and extracellular volume fraction (ECV) derived from CMR with the degree of collagen on endomyocardial biopsy (EmBx), and to investigate the association between myocardial fibrosis and clinical as well as functional markers in children after HTx. In spite of substantially improved survival following paediatric heart transplantation (HTx) over the past two decades [1], significant morbidity still prevails, some of it limiting the survival of the graft organ [1, 2]. We hypothesized that native T1 and ECV are associated with the histological degree of fibrosis within the myocardium of pediatric HTx recipients
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