Impact of conotruncal anomalies on outcomes following total cavopulmonary connection

Abstract Objectives: The impact of conotruncal anomalies on long-term outcomes after total cavopulmonary connection remains unclear, particularly regarding haemodynamic performance and dominant ventricular morphology. Methods: All patients who underwent total cavopulmonary connection between 1994 and 2023 at a single centre were reviewed. Conotruncal anomalies were defined as transposition of the great arteries, double outlet right ventricle, tetralogy of Fallot, truncus arteriosus, and interrupted aortic arch type B. Four endpoints were analysed: transplant-free survival, Fontan failure, tachyarrhythmia, and ventricular dysfunction. Multivariable Cox regression, inverse probability of treatment weighting, and subgroup analyses were performed to disentangle conotruncal anomaly effects from dominant ventricular morphology. Results: Among the 650 patients, 291 (44.8%) were identified with conotruncal anomalies. During a median follow-up of 6.3 years, no differences were observed in transplant-free survival (log-rank p = 0.136) or Fontan failure ( p = 0.717) between groups. Dominant right ventricular morphology was independently associated with Fontan failure (hazard ratio: 2.20; p = 0.006) and tachyarrhythmia (hazard ratio: 3.22; p = 0.004). These findings were confirmed across all sensitivity analyses. No differences were detected in filling pressures, cardiac index, or peak oxygen uptake on post-operative catheterisation ( n = 226) and cardiopulmonary exercise testing ( n = 161). When stratified into four groups by conotruncal status and dominant ventricular morphology, freedom from Fontan failure clustered by morphology rather than diagnostic category (4-way log-rank p < 0.001). Conclusions: Conotruncal anomalies are not independently associated with adverse outcomes following total cavopulmonary connection. Dominant right ventricular morphology, not diagnostic category, is the principal determinant of long-term Fontan outcomes.