ARNI Versus plAcebo in Patients With Congenital sYStemic Right Ventricle Heart Failure

Inclusion Criteria: * Age \> or egal18 years with clinical follow-up at the Montreal Heart Institute Adult Congenital Heart Center * Systemic right ventricle (transposition of great vessels and atrial switch or congenitally corrected transposition of great vessels) * Moderate to severe systemic right ventricle dysfunction by transthoracic echocardiography (TTE) or right ventricle ejection fraction (RVEF) \<40% by MRI * NYHA Functional class II-III symptoms or peak exercise capacity \<80% of predicted on a previous standard treadmill exercise stress test (usually done every two years in our congenital clinic). * Ability to provide informed consent to the study * Access or own a telephone and/or access to internet connection for teleconference call * Own a mailing address to receive the medication by post (FedEx or Dicom) * Able to perform self-measurement of the blood pressure using Upper Arm Digital Blood Pressure Monitor as recommended by Hypertension Canada. Exclusion Criteria: * Participation in a clinical trial of an investigational drug, concurrently, or within the last 30 days prior enrolment * Planned cardiac surgery (e.g., severe tricuspid regurgitation with planned tricuspid valve replacement or repair) * Previous cardiac transplantation, or on heart transplant wait list * Myocardial infarction, stroke, or open-heart surgery in the previous 4 weeks * NYHA Functional class I or IV symptoms * Symptomatic hypotension (fainting, dizziness, lightheadedness, blurred vis…