Ventricular Morphology and Outcomes in Fontan Circulation without Hypoplastic Left Heart Syndrome: A Single-Center's Experience

Background: The impact of dominant ventricular morphology on Fontan patient outcomes remain controversial. This study evaluates long-term results of right ventricle (RV) dominance versus left ventricle (LV) dominance in Fontan circulation without hypoplastic left heart syndrome (HLHS).

Methods: We retrospectively examined 323 Fontan operations from our center. To minimize pre- and intra-Fontan heterogeneity, 42 dominant RV patients were matched with 42 dominant LV patients using propensity score matching, allowing for a comparative analysis of outcomes between groups.

Results: The mean follow-up was 8.0 $\pm$ 4.6 years for matched RV dominant and 6.5 $\pm$ 4.7 years for matched LV dominant group (p $>$ 0.05), showing no significant difference. The cumulative incidence of moderate or greater atrioventricular valve regurgitation was also comparable between the two groups (p $>$ 0.05). Similarly, 10-year freedom from death or transplantation following the Fontan operation was 84% $\pm$ 7% in the matched dominant RV group, similar to 81% $\pm$ 7% in the matched dominant LV group (p $>$ 0.05). The 10-year freedom from Fontan failure was 78% $\pm$ 8% in the matched dominant RV group, also similar to 75% $\pm$ 8% in the matched dominant LV group (p $>$ 0.05). Multivariate analysis did not identify RV dominance as a risk factor for Fontan failure (p $>$ 0.05).

Conclusions: In the pre- and intra-Fontan context, RV dominance demonstrated similar and comparable long-term outcomes compared to LV dominance in non-HLHS Fontan circulation.