Patients with repaired tetralogy of Fallot (RTOF) develop chronic pulmonary regurgitation and require monitoring for right ventricular dilatation. Pulmonary valve replacement can prevent irreversible right ventricular (RV) dilatation and dysfunction and cardiac magnetic resonance (CMR) is used to facilitate its optimal timing. The investigators sought to determine whether the choice of myocardial contouring technique affects preoperative RV volumetric thresholds for intervention.

Participants with repaired tetralogy of Fallot (RTOF) will be identified using existing patient electronic records who have developed chronic pulmonary regurgitation and are undergoing monitoring for right ventricular dilatation. Cardiac magnetic resonance (CMR) is used to facilitate its optimal timing. Pulmonary valve replacement can prevent irreversible right ventricular (RV) dilatation and dysfunction and cardiac magnetic resonance (CMR) is used to facilitate its optimal timing. There are different post-processing techniques published for measuring RV volumes on cardiac magnetic resonance imaging (detailed vs. smoothed and manual vs. automated). The primary aim of this study is to identify whether the choice of myocardial contouring technique affects the preoperative RV volumetric thresholds for intervention. As a secondary aim, the investigators will determine the reproducibility of different contouring methods.

Inclusion Criteria:

• Consecutive patients with repaired Tetralogy of Fallot undergoing routine clinical surveillance at a Level 1 ACHD surgical referral centre.

Exclusion Criteria:

• None

Patients with repaired tetralogy of Fallot (RTOF) with chronic pulmonary regurgitation who require monitoring for right ventricular dilatation.