Conclusions
In Fontan patients, cardiac magnetic resonance evidence of myocardial fibrosis is associated with diastolic dysfunction, increased liver stiffness and elevated circulating biomarkers of fibrosis. These findings suggest the presence of a profibrotic milieu, with end-organ implications, in some patients with Fontan circulation.
Methods
Prospective observational study of Fontan patients who had a cardiac catheterisation. Cardiac MRI with T1 mapping was obtained to measure extracellular volume (ECV), a marker of myocardial fibrosis. Hepatic magnetic resonance elastography was performed to assess liver shear stiffness. Serum biomarkers of fibrosis including matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) were measured. Very high ECV was defined as >30% and elevated serum biomarkers as >75th percentile for each biomarker.
Results
25 Fontan patients (52% female) with mean age of 16.3±6.8 years were included. Mean ECV was 28%±5%. There was a significant correlation between ECV and systemic ventricular end-diastolic pressure (r=0.42, p=0.03) and between ECV and liver stiffness (r=0.45, p=0.05). Patients with elevated ECV demonstrated elevations in MMPs and TIMPs. Similarly, patients with elevated MMPs and TIMPs had greater liver stiffness compared with patients with normal levels of these biomarkers. Conclusions: In Fontan patients, cardiac magnetic resonance evidence of myocardial fibrosis is associated with diastolic dysfunction, increased liver stiffness and elevated circulating biomarkers of fibrosis. These findings suggest the presence of a profibrotic milieu, with end-organ implications, in some patients with Fontan circulation.