The objective of this study was to determine the evolution of fibrosis over time and its association with clinical status.

Children with repaired tetralogy of Fallot who had undergone at least two cardiac magnetic resonance examinations including T1 mapping at least 1 year apart were included.

Thirty-seven patients (12.7 ± 2.6 years, 61% male) were included. Right ventricular free wall T1 increased (913 ± 208 versus 1023 ± 220 ms; p = 0.02). Baseline cardiac magnetic resonance parameters did not predict a change in imaging markers or exercise tolerance. The right ventricular free wall per cent change correlated with left ventricular T1% change (r = 0.51, p = 0.001) and right ventricular mass Z-score change (r = 0.51, p = 0.001). T1 in patients with late gadolinium enhancement did not differ from the rest.

Increasing right ventricular free wall T1 indicates possible progressive fibrotic remodelling in the right ventricular outflow tract in this pilot study in children and adolescents with repaired tetralogy of Fallot. The value of T1 mapping both at baseline and during serial assessments will need to be investigated in larger cohorts with longer follow-up.