Diffuse Myocardial Fibrosis in Children After Heart Transplantations: A Magnetic Resonance T1 Mapping Study
Eugénie Riesenkampff1, Ching Kit Chen, Paul F Kantor
11 Division of Cardiology, Department of Pediatrics, Labatt Family Heart Centre, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada. 2 Stollery Children's Hospital, Department of Pediatric Cardiology, Edmonton, Alberta, Canada. 3 Alberta Children's Hospital, Section of Cardiology, University of Calgary, Calgary, Alberta, Canada. 4 Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada. 5 Siemens AG Healthcare Sector, Erlangen, Germany.
Insights
Pediatric heart transplant recipients show evidence of diffuse myocardial fibrosis. This condition is linked to diastolic dysfunction, suggesting accelerated fibrotic remodeling post-transplant.
Area of Science:
- Cardiology
- Pediatric Cardiology
- Transplantation Medicine
Background:
- The long-term effects of heart transplantation (HTx) on myocardial remodeling in children are not well understood.
- Accelerated fibrotic remodeling is a potential concern after pediatric HTx.
Purpose of the Study:
- To investigate the presence and extent of diffuse myocardial fibrosis in children following heart transplantation.
- To assess the association between myocardial fibrosis and diastolic dysfunction in this population.
Main Methods:
- Prospective study comparing cardiac magnetic resonance (CMR) imaging in 17 pediatric HTx patients and 9 healthy controls.
- T1 measurements and calculation of the tissue-blood partition coefficient (TBPC) to quantify diffuse myocardial fibrosis.
- Correlation of CMR findings with echocardiographic parameters of diastolic function.
Main Results:
- Significantly higher native T1 times in HTx patients compared to controls across all myocardial regions.
- Elevated TBPC in the left ventricular free wall and entire LV myocardium of HTx patients.
- Native T1 times correlated with LV E/e', an echocardiographic marker of diastolic dysfunction.
Conclusions:
- Diffuse myocardial fibrosis is present in children after heart transplantation.
- This fibrosis appears to be associated with diastolic dysfunction, indicating potential accelerated fibrotic remodeling.
Background:
It is unclear whether the myocardium undergoes accelerated fibrotic remodeling in children after heart transplantation (HTx).
Methods:
In this prospective study, cardiac magnetic resonance (CMR) studies in 17 patients 1.3 years (median, range 0.03-12.6 years) after HTx (mean age, 9.8 ± 6.2 years; 8 girls) were compared to CMR studies in 9 healthy controls (mean age, 12.4 ± 2.4 years; 4 girls). T1 measurements were performed at a midventricular short axis slice before (ie, native T1 times) and after the application of 0.2 mmol/kg gadopentetate dimeglumine in the interventricular septum, left ventricular (LV) free wall and encompassing the entire LV myocardium. The tissue-blood partition coefficient (TBPC), reflecting the degree of diffuse myocardial fibrosis, was calculated as a function of the ratio of T1 change of myocardium compared to blood. Native T1 times and TBPC were correlated with echocardiographic parameters of diastolic function.
Results:
Native T1 times were significantly higher in HTx patients compared to controls in all regions assessed (LV free wall 973 ± 42 vs 923 ± 12 ms; P < 0.005; interventricular septum 1003 ± 31 vs 974 ± 21 ms, P < 0.05; entire LV myocardium 987 ± 33 vs 951 ± 16 ms; P < 0.005) and correlated with LV E/e' as an echocardiographic marker of diastolic dysfunction (r = 0.54, P < 0.05). The TBPC was elevated in the LV free wall (0.45 ± 0.06 vs 0.40 ± 0.03, P < 0.005) and the entire LV myocardium (0.47 ± 0.06 vs 0.43 ± 0.03, P < 0.05).
Conclusions:
Evidence of diffuse myocardial fibrosis and is already present in children after HTx. It appears to be associated with diastolic dysfunction.
