Effects Branch PA Stenting d-TGA, ToF and TA

Rationale: Postoperative survival of patients with dextro transposition of the great arteries (d-TGA), Tetralogy of Fallot (ToF) and Truncus Arteriosus (TA) has increased over the last decades due to advances in operative techniques and perioperative care. Despite postoperative survival has increased, morbidity of these patients increases during long-term follow-up with a high need for reinterventions. Right ventricular outflow tract (RVOT) obstructions are the most common indication for a reintervention and percutaneous branch pulmonary artery (PA) interventions account for a significant number of these reinterventions. However, the effects of percutaneous branch PA interventions on exercise capacity, RV function and RV adaptation of patients with d-TGA, ToF and TA remains largely unknown. In addition, there is no consensus about the optimal timing for percutaneous interventions for branch PA stenosis in international guidelines.

Objective: The primary study objective is to identify the effects of percutaneous interventions for branch PA stenosis on exercise capacity in patients with d-TGA, ToF and TA. The secondary objectives are 1) to assess the effects of percutaneous interventions for branch PA stenosis on RV function and 2) to define early markers for RV function and adaptation to improve timing of these interventions.

Study design: This is a multicenter randomized controlled trial. Patients will be included from the following Dutch interventional centers for congenital heart disease: UMC Utrecht/WKZ (sponsor), LUMC/AUMC and Erasmus MC. During this trial there will be two groups: 1. a group of patients with d-TGA, ToF and TA who will undergo a percutaneous intervention for a branch PA stenosis according to standard care (intervention group) and 2. a group of patients with d-TGA, ToF and TA with a similar degree of pulmonary stenosis as group 1 (class IIa indication) who will undergo conservative management for a branch PA stenosis according to standard care (control group). If necessary, the control group will be able to undergo a percutaneous intervention for branch PA stenosis after the examinations at approximately 6 months follow-up, or sooner in case of symptoms. Patients from both groups will undergo the same series of examinations at baseline and approximately 6 months follow-up (within 6 week time-range) as part of standard care: conventional transthoracic echocardiogram (TTE), cardiopulmonary exercise testing (CPET) and conventional Cardiac Magnetic Resonance (CMR) including a low dose dobutamine stress MRI to assess RV functional reserve. The low dose dobutamine stress MRI will be performed in the interventional group from the UMC Utrecht/WKZ and Erasmus MC because the LUMC and AUMC do not have a suitable infrastructure for the low dose dobutamine stress MRI and this cannot be achieved throughout the duration of this study. The baseline CMR in the interventional group will be performed as close as possible prior to the intervention but maximal 4 weeks prior to the intervention. In addition, the intervention group will undergo standard RV pressure measurements during the intervention. Quality of life (QoL) questionnaires will be obtained at baseline and 2 weeks post intervention (intervention group) or a similar time range in the control group, which is based on experts opinion. TTE, CPET and conventional CMR will be performed within 2-4 years follow-up to assess the long-term effects of percutaneous PA interventions.

Study population: d-TGA post ASO, ToF or TA patients ≥8 years old will be included if they have a class IIa indication for a percutaneous intervention for branch PA stenosis according to the international guidelines. Patients will be excluded if they contraindications for one of the examinations.

Main study parameters/endpoints: the difference in VO2 max (% predicted) as parameter for exercise capacity between the interventional and control group.

• Technical success using invasive right ventricular and pulmonary artery pressures and gradients [Time frame: after the intervention, an average of 1 month after baseline]
• Peak workload (W) [Time frame: at baseline, 6 months follow-up and 2-4 years follow-up]
• Peak workload (% predicted) [Time frame: at baseline, 6 months follow-up and 2-4 years follow-up]
• O2 pulse (ml) [Time frame: at baseline, 6 months follow-up and 2-4 years follow-up]
• O2 pulse (% predicted) [Time frame: at baseline, 6 months follow-up and 2-4 years follow-up]
• VE/VCO2 slope [Time frame: at baseline, 6 months follow-up and 2-4 years follow-up]
• Right ventricular ejection fraction (%) [Time frame: at baseline, 6 months follow-up and 2-4 years follow-up]
• RV strain (%) [Time frame: at baseline, 6 months follow-up and 2-4 years follow-up]
• RV fractional area change (%) [Time frame: at baseline, 6 months follow-up and 2-4 years follow-up]
• RV pressure (mmHg) [Time frame: at baseline, 6 months follow-up and 2-4 years follow-up]
• RV end-systolic elastance [Time frame: before and after the intervention, an average of 1 month after baseline]
• RV end systolic volume (ml and ml/m2) [Time frame: at baseline, 6 months follow-up and 2-4 years follow-up]