Ventricular Dominance and Cardiac Morphology as Independent Predictors of the Outcome of Fontan Procedures—A Single-Center Experience

Objectives: Varying diagnoses lead to surgical palliation with the Fontan procedure. However, it is unclear, whether the underlying diagnoses determine short- and long-term outcomes or if ventricular dominance influences outcome, independent of the surgical approach.

Methods: A total of 801 patients undergoing Fontan procedures at Boston Children’s Hospital from January 2000 to December 2017 were included in this retrospective analysis. Patients were categorized based on diagnosis leading to a Fontan procedure as well as on their ventricular dominance (left or right dominant). Intraoperative (total bypass time and cross-clamp time), early postoperative (intensive care unit stay, hospital stay, ventilation time, chest tube effusion time, and early mortality), and late postoperative outcomes (revision and exercise/stress testing) were used for analysis. Major complications such as mortality, Fontan failure, thrombosis, and pacemaker implantations were observed using Cox regression time-to-event models. Other complications (arrhythmias, protein-losing enteropathy, baffle leaks, volume overload, and plastic bronchitis) were noted.

Results: Around half (51%) of all Fontan patients were diagnosed with hypoplastic left heart syndrome, the rest of the patients had the following diagnoses: 17% pulmonary atresia, 10% tricuspid atresia, 10% double inlet left ventricle, 10% unbalanced AV canal, double outlet right ventricle, 1% transposition of the great arteries, and 1% others; 59% were categorized as right dominant (RD) and 41% as left dominant ventricles. For underlying diagnosis, patients with unbalanced AV canal had a significant higher early (6%) and late (34%) mortalities and a higher rate of Fontan failures (18%) than any other diagnosis group. Comparing RD and LD, early hospital mortality was similar, although total mortality was significantly higher in RD group (8 vs. 4%, p = 0.04) and the rate of pacemaker implantations was also higher in the RD compared with LD (9 vs. 5%, p = 0.02).

Conclusion: Independently of the surgical approach, patients with unbalanced AV canal or RD ventricles have worse short- and long-term outcomes. These data suggest that a RD ventricle is an independent risk factor for morbidity in this patient cohort.