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 vision, weakness, fatigue, nausea, palpitations, and headache) with a systolic blood pressure <100 mmHg at screening, or asymptomatic <90 mmHg at screening eGFR <30 mL/min/1.73 m2 Reduction in eGFR >35% from screening to randomization Potassium >5.2 mmol/L at screening or >5.4 mmol/L at randomization Known history of angioedema related to previous ACEI or ARB therapy or patients with a history of hereditary or idiopathic angioedema. Patients who require concomitant treatment with an angiotensin converting enzyme inhibitor (ACEI) or an angiotensin receptor blocker (ARB) or a renin inhibitor for other indication than heart failure Evidence of hepatic disease as determined by any one of the following: serum glutamate oxaloacetate transaminase (SGOT) or serum glutamate pyruvate transaminase (SGPT) values exceeding 3x upper limit of normal, bilirubin >1.5 mg/dl at screening. Unacceptable side effects with ACE-inhibitors or ARBs Patient known with bilateral renal artery stenosis Cyanosis; substantial left-to-right shunting (Qp/Qs >1.5); severe mitral, aortic, or pulmonary regurgitation; systemic or pulmonary inflow obstruction with a peak velocity >1.5 m/s by transthoracic echocardiography; and severe outflow tract obstruction with a peak systolic gradient >80 mm Hg. Inability to provide informed consent Unable to exercice Pregnant or planned pregnancy during the study Breastfeeding Severe pulmonary hypertension defined as pulmonary pressure egal or superior to systemic pressure