Fontan conversion: guidelines from Down Under

Patients who have had an atriopulmonary Fontan may develop a dilated atrial connection that can lead to atrial arrhythmias and low cardiac output from inefficient venous flow. These patients are treated medically with anti-arrhythmic medications and transcatheter ablations, but still have declining exercise tolerance and progressive congestive heart failure. The surgical treatment for appropriate candidates is the Fontan conversion procedure with arrhythmia surgery. This operation successfully addresses these problems in a majority of patients and improves their quality of life and transplant-free survival [ 1 ]. The difficult decision for cardiologists caring for these patients is when to refer them for Fontan conversion. This is a major open heart operation with definite risks of morbidity and mortality; the Society of Thoracic Surgeons database operative mortality rate following Fontan conversion was 11% [ 2 ]. However, after a successful Fontan conversion, most patients have a marked improvement in their exercise capability, lifestyle, and transplant-free survival.

The recent paper from Down Under may help clinicians in making the decision about when to refer patients for Fontan conversion. Dr. Poh and colleagues performed a comparison between the outcomes at 6 centres in Australia and New Zealand which had two different treatment strategies, early vs late referral for Fontan conversion [ 3 ]. Thirty-nine patients underwent Fontan conversion at six centres. Early vs late referral was defined by the time from onset of arrhythmia to Fontan conversion. One centre had a lower (early) threshold to refer for Fontan conversion. The number of patients undergoing Fontan conversion at that centre was similar to those undergoing Fontan conversion at the other 5 centres combined. The early centre performed the Fontan conversion at a mean interval of 3 years after the first documented arrhythmia vs 4 years at the late conversion centres. The average New York Heart Association classification was II at the early centre vs III for the late referring centres. Finally, the mean number of preoperative anti-arrhythmic medications was 1 (early centre) vs 2 (late centre). Following the Fontan conversion, the incidence of major cardiac-related complications was 2/17 at the early centre vs 7/22 at the late centres ( P = 0.14). More importantly, the eight-year rate of freedom from death or heart transplantation was 86% in the early conversion group vs 51% in the late conversion group ( P = 0.007).

The message here is that early referral based on these criteria led to improved outcomes. However, it is also possible that the single centre that favoured early conversion had the institutional experience and expertise with a greater number of patients, which may have improved their outcomes. Whether the improved results reported in this study are actually attributable to earlier referral or increased centre experience is not totally clear. The other 5 centres may not have had the same depth of expertise as the single centre favouring early Fontan conversion. The sample size is insufficient to perform multivariate analysis to adjust for such factors. The authors have noted this as a potential limitation in their manuscript.

Our own single-centre series includes 146 Fontan conversions with an early mortality rate of 2%. The rate of freedom from late recurrence of atrial tachycardia was 77% at 10 years. Risk factors for transplant or death included dominant right ventricle or morphologically indeterminate ventricle, ascites, and protein-losing enteropathy [ 1 ]. The presence of ascites or protein-losing enteropathy reflects an advanced state of failing Fontan physiology, and our policy now is to refer these patients for consideration for heart transplantation. These patients would potentially have benefited from earlier referral. The multicentre data reported by Diller et al. also shows the profoundly negative transplant-free survival for adults with atriopulmonary Fontan operations with atrial arrhythmias and diuretic usage [ 4 ]. The challenge with atriopulmonary Fontan patients is to refer them prior to the development of ventricular dysfunction or multisystem organ failure. We agree that earlier referral will improve outcomes for Fontan conversion.

The number of patients surviving with an atriopulmonary Fontan who are without conversion or transplantation is decreasing rapidly as the years go by. The possibility of a randomized, multicentre study looking at the timing of referral is not feasible given the fact that this is a decreasing/dwindling patient population. The remaining patients need to be carefully evaluated for potential surgical referral before it is too late for Fontan conversion to be successful. Based on the experience reported from Down Under, they should be referred early! Equally important, they should be treated at an institution with the expertise to deal with this complex patient population. An analysis of our 146 cases would support their findings.

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