Angiotensin-Converting Enzyme (ACE) inhibitor cessation in the setting of well-functioning Fontan hearts

This study will look at the impact of angiotensin receptor inhibitors (ACEI) cessation in children and adults with a Fontan circulation and normal heart contraction. Many children born with a single cardiac pumping chamber undergo a Fontan operation. Due to concerns about potential late heart failure, many are prescribed ACEI although they have good heart function, possibly exposing them to unnecessary risk of adverse drug reactions and the burden of lifelong medication. Evidence has shown ACEI are of benefit in a failing 2-ventricle heart, but there is no literature to suggest they are of benefit in the Fontan circulation. This project aims to demonstrate that cessation of ACEI, or closely related angiotensin receptor blockers (ARB), is safe and non-inferior to ACEI/ARB continuation in children and adults with a Fontan circulation with good cardiac systolic function and without other indications for continuation such as moderate or greater valvar regurgitation and/or hypertension. We hypothesise that: 1. Cessation of ACEI or ARB does not result in a significant decline in peak exercise capacity or cardiac function over a 12-month follow-up period. 2. Cessation of ACEI or ARB results in improved quality of life and reduced medical expenses over 12 months. If the hypotheses hold true it will dispel a historical concern that will relieve a large number of Fontan patients and their families of an unnecessary burden, improving quality of life and sense of well-being. It will improve the futures and the lives of people affected by childhood heart disease. Lifelong medication carries with it an important psychological burden because of the effects on one’s sense of well-being and “normalness”. This can be especially burdensome for children and their families. Medications also impose a risk of adverse reactions, and may also be costly, for example an adult on a standard dose of ACEI without a Healthcare Card could expect to pay $265 per year. Although, in this current era, we strive for evidence-based medical practice, there is little evidence to guide us in many areas of congenital heart medicine. Some practices, that have been routine for many years, may actually be useless or even cause harm. The implementation of ACEI as a routine for people with the unique single-ventricle Fontan circulation is practiced in many centres, although there is virtually no evidence to support their use. Future implications of this trial would include reduced morbidity related to unnecessary medication administration, insight into the disease processes that may or may not contribute to late Fontan failure, a better understanding of the consequences of ACEI use including the social and psychological impact, improved quality of life, and streamlined and improved management strategies for people living with a Fontan heart.