Extracardiac Conduit Fontan – Outcome Data in Early Adulthood

Background

To describe the survival and health outcome status of young adults with an extracardiac Fontan procedure performed either as a primary or conversion (secondary) Fontan surgery.

Methods

The database of the Adult Congenital Heart disease service at the Royal Melbourne Hospital was interrogated to identify all adults who had undergone a primary extracardiac conduit Fontan (n = 29) or a Fontan conversion with this procedure (n = 8). We then determined vital status, age, original anatomy and functional status in early adulthood in both groups.

Results

Adults with an ECC Fontan procedure report reasonable NYHA functional class (84% NYHA I or II) though, objectively, exercise testing demonstrates a reduced exercise capacity, and desaturation on exertion is frequent. The majority (86%) have completed secondary education. Most (78%) are managed on warfarin and there is a preponderance of ACE inhibition use (62%). Atrial arrhythmias have been documented in 5 of the 29 primary ECC groups (17%); in 3 patients this preceded primary ECC and 2 patients developed post primary ECC (between 6 and 14 years postoperatively). At a lesser time of follow-up [median 4.5 years (IQR 3.3–6)], conversion to an ECC as a secondary Fontan procedure has successfully treated atrial arrhythmias in the 7 (of 8) patients where this was the surgical indication for conversion.

Conclusions

Though long-term data will require decades to establish, in young adulthood the functional outcomes of a primary ECC Fontan operation are encouraging. Secondary ECC conversion successfully mitigates atrial arrhythmias in the short to medium term.

Introduction

A Fontan circulation is the final destination surgery for children with cardiac anatomy not suitable for a two-ventricle repair. The most recent version of the surgically created Fontan circulation is the extra cardiac conduit (ECC) [1], with surgical innovation driven by recognition of the propensity for clot formation, atrial arrhythmias and energy loss within the original atriopulmonary Fontan connection.

The time required to ascertain long-term sequelae of refinements in surgical approach, makes determination of outcomes an ongoing priority in adults with congenital heart disease. Additionally, in patients with earlier Fontan surgery, conversion to an ECC may occur in adulthood, with the commonest indication being atrial arrhythmias. How, and whether, this Fontan conversion will impact long-term outcomes remains unclear. Recent publication of local data from the Australia and New Zealand Fontan Registry (ANZ Registry) shows significant early mortality with this approach, though postoperative outcomes are better in those who undergo conversion earlier in life [2].

Available literature suggests that individuals with an ECC Fontan may have less arrhythmia over the short term [3], [4]. Medium-term follow-up in more recent studies has not determined any difference in arrhythmia incidence [5], [6]. ANZ Registry data is encouraging, but again limited in only showing data to approximately 15 years post Fontan surgery in the ECC cohort [7]. Questions remain about the long-term benefit of this approach with respect to arrhythmia incidence and, particularly, the challenges of subsequent treatment, if required, with this circuit [8], [9]. Locally, surgical adoption of the ECC Fontan connection commenced in 1998 and became the exclusive Fontan procedure in 2006 [10].

To date, within the population of Fontan circulation patients, worse outcomes have been demonstrated for those with hypoplastic left hearts (HLHS) [7]. There is little long-term data on this particular subgroup of Fontan patients. Proportionally, they are over-represented within the ECC cohort as compared with other Fontan operations, as they have become eligible for a Fontan procedure more recently than individuals with other anatomical diagnoses.

In view of the questions that remain about longer-term outcomes of patients with ECC Fontan circulation, those with an anatomical diagnosis of HLHS and adults who have undergone ECC conversion, we sought to ascertain the outcomes in our cohort of patients in early adulthood. Ethics approval was granted by the Human Research and Ethics Committee of the Royal Melbourne Hospital (QA2015015).