Sinus venosus defect (SVD) accounts for 10% of atrial septal defects and is characterized by an anomalous pulmonary venous return in the superior vena cava associated with a high situated atrial septal defect. Since 2013, transcatheter correction of this congenital heart disease has emerged as a new treatment option. The procedure involves placement of a covered stent in the superior vena cava that tunnels the anomalous pulmonary venous return to the left atrium. Preliminary results are limited but promising. The devices to be used depend on anatomic considerations. XXL stents than 70mm are often required. Today, the availability of CE marked stents is limited. There have been recent reports of successful corrections with the specifically developed Optimus XXL 100mm covered stent (ANDRATEC) with compassionate approval from the Agence Nationale de Sûreté du Médicament in France. Setting up a feasibility study to investigate the use of medical devices in this indication was required. The objective of this project is to study the feasibility, efficacy and safety of the Optimus stent in this newly developed transcatheter procedure, in comparison with the gold-standard surgical method. A French national multicenter comparative cohort study including all eligible patients referred for transcatheter correction of SVD was designed. The feasibility of the transcatheter procedures will be investigated beforehand by virtual digital simulation and simulation on a 3D printed model. The procedures will then be performed in centers of the M3C network for complex congenital heart diseases (CARDIOGEN). The primary endpoint will be a composite of efficacy, defined as complete occlusion of the shunt, and safety, defined as the absence of major events at 6 months. The secondary endpoints will be anatomical, functional and psychosocial (quality of life). It is expected that transcatheter treatment gives comparable results to surgery on the primary endpoint. This could justify the further development of this procedure as an alternative to surgery and facilitate the validation of dedicated equipment.