With the crucial caveat of donor organ availability, orthotopic heart transplant is an effective treatment for end stage heart failure of many causes, including congenital heart disease1. Specific considerations are required for Fontan patients, who are heterogeneous in every aspect and whose clinical decline and mechanisms of failure often embroil organ systems beyond the heart.

With contemporary management, Fontan failure in childhood has become relatively rare. Analysis of the 500 children who underwent Fontan completion at Toronto’s SickKids Hospital between 1985 and 2012, found those operated on after 1999 had improved outcomes as compared the cohort with Fontan completion prior to 1999. ² Freedom from death or transplant in the modern era was 97%, 96% and 96% at 5 years, 10 years and 15 years.² This is not to say that that children with a Fontan circulation can now all anticipate reaching adulthood complication-free, but rather that the epidemiology of Fontan failure is shifting and along with other advanced management options, transplant in this population is increasingly becoming the purview of adult congenital heart disease (ACHD) specialists and adult transplant programs.

Although heart transplant after a Fontan procedure can be achieved with excellent outcomes³, registry data consistently demonstrate decreased early survival in adult Fontan heart transplant recipients as compared those transplanted for either biventricular congenital heart disease or cardiomyopathy. A 2019 analysis of all adults who underwent heart transplant in United States hospitals 2004-2014 included 93 Fontan patients and found their in-hospital, post-transplant mortality that was five times that of non- Fontan recipients (26% vs 5%, p <0.001)⁴. Concern over such discrepant outcomes understandably raises a barrier and is likely at least part of the reason that most adults dying from a failing Fontan circulation are not referred for or offered transplant.⁵ However, inclusive of highly variable transplant assessment, surgical and postoperative management practices, this type of data tells only part of the story.

With such potential variety and complexity (different types of Fontan surgery, residual anatomical concerns, degrees of liver, lymphatic and renal involvement, levels of HLA sensitization and other issues) some centres, regions and even countries have evolved a highly-specialized approach to adult Fontan transplant. Establishing dedicated multidisciplinary teams who pay close attention and apply their unique skill-sets to every aspect of the process: transplant assessment and listing, clinical optimization pre-transplant, donor organ selection and transport, recipient anesthesia, surgical technique and postoperative care^6,7. The intent is to produce incremental improvements in outcome that mirror the experience of paediatric Fontan transplant.^8,9 Data from the Paediatric Heart Transplant Study database for Fontan patients shows improvement in 1-year survival from 77% (1993-2006) to 89% (2007-2014)8 with no survival difference between children transplanted for Fontan and those transplanted for other congenital heart disease10. Others report similar paediatric progress^9,11. While adult Fontan transplant likely has additional challenges, following a more structured approach, at least one group has demonstrated era on era improvement¹² such that their adult Fontan/ single ventricle heart transplant results have become equivalent to their adult biventricular congenital transplant outcomes¹³. Supplementary advantages are: (1) some Fontan patients initially referred for transplant may be found to have non-transplant, surgical or transcatheter options that are within the risk tolerance of sub-specialty centres and (2) consolidating accelerates the learning curve and establishes a rich clinical resource for future training and research.

The necessity of highly specialist and multidisciplinary expertise together with a likelihood of better outcomes from higher volume centres, should encourage provincial and national decision-making about the development and optimization of clinical services for the growing number of adult Canadians facing Fontan failure both now and in the future^7,14. Given that a small percentage of failing Fontan patients will require combined heart and liver transplant and that all those being considered for heart transplant also need specialist hepatic assessment, it would seem sensible to have both heart and liver transplant services on-site. We should recognize that Canadian geography, societal demographics and the psychosocial issues affecting ACHD patients are all additive to the technical and political challenges of transplant in the Fontan population. Investigators in Australia and New Zealand found such issues created important regional differences in the rates of Fontan heart transplant, suggesting that systemic obstacles and biases can limit access⁵. This situation might be mitigated if considered from the outset when planning the structure of Canadian Fontan transplant referral and management pathways.

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