Hypoplastic Left Heart Syndrome Is Not a Predictor of Worse Intermediate Mortality Post Fontan.

Background: An increasing proportion of those living with single ventricle physiology have hypoplastic left heart syndrome (HLHS). Our objective was to assess the association between HLHS and outcomes post Fontan operation.

Methods: All pediatric patients who underwent a Fontan procedure at the University of Alberta between 1996 and 2016 were included. Follow-up clinical data collected included early and late surgical or catheter reintervention, echocardiography, and long-term transplant-free survival. Characteristics were compared between those with and without HLHS, and the association between outcomes and HLHS were assessed.

Results: A total of 320 children (median age 3.3 years, interquartile range 2.8 to 3.9 years; 121 [43.4%] female) underwent a Fontan procedure over the course of the study. Nearly one third of subjects had HLHS (107, 33.4%). Patients with HLHS were more likely to have abnormal ventricular function (19.6% versus 7.0%, p = 0.003) and worse than mild atrioventricular valve (AVV) regurgitation (23.4 versus 9.2%, p = 0.001) preoperatively. HLHS was not predictive of in-hospital Fontan failure (odds ratio 0.82, 95% CI 0.28, 2.39), late reintervention (hazard ratio [HR] 1.08, 95% CI 0.66, 1.76), or transplant-free survival (HR 1.58, 95% CI 0.72, 3.44). Subjects with HLHS were more likely to have more than mild AVV regurgitation (31.6% versus 13.3%, p = 0.028) and abnormal ventricular function (29.8% versus 10.7%, p < 0.0001) at late follow-up.

Conclusions: Patients with HLHS who survive to the Fontan procedure do no worse with the operation than those with other anatomy. Given worse late ventricular function and AVV regurgitation, equivalent survival may not persist throughout a patient's life course.