Heterotaxy is not a risk factor for adverse long-term outcomes following Fontan completion.

Heterotaxy is considered to be a risk factor for poor outcomes after the Fontan operation. However, long-term data to support this notion are lacking. The aim of our study was to ascertain the long-term outcomes of patients with heterotaxy following hospital discharge after Fontan completion and compare them with a contemporary non-heterotaxy cohort.A bi-national Fontan Registry (n =1,540) was analysed to identify heterotaxy patients and compare with non-heterotaxy patients. The primary composite end point was 'Fontan failure' encompassing death, heart transplantation, Fontan takedown or conversion, protein-losing enteropathy, plastic bronchitis, or New York Heart Association functional class III or IV.One hundred and nine heterotaxy patients were identified which were compared with 1,431 non-heterotaxy Fontans following Fontan completion. There was no difference in unadjusted 15-year freedom from Fontan failure (heterotaxy: 78% vs non-heterotaxy: 85%, p=0.2). Patients in the heterotaxy group had a significantly higher cumulative incidence of post-Fontan arrhythmias (p<0.001). Propensity-score matching for confounders yielded 73 heterotaxy patients matched with 439 non-heterotaxy patients, in which 15-year freedom from Fontan failure was also not different (heterotaxy: 76% vs non-heterotaxy: 81%, p=0.2). There was no difference in 15-year freedom from Fontan failure in patients with right vs left isomerism (right isomerism: 80% vs left isomerism: 76%, p=0.7).Whilst heterotaxy may complicate the pre-Fontan course, once the Fontan is successfully completed it does not appear to be an important risk factor for Fontan failure. Heterotaxy patients are at a higher risk of post Fontan arrhythmias compared to non-heterotaxy patients.