Clinical implications of progressive systemic ventricular dysfunction in adults with Fontan palliation.

Background: The purpose of this study was to determine the clinical implications of progressive systemic ventricular (SV) systolic dysfunction in adults with Fontan palliation. Methods: Retrospective study of Fontan patients with ≥2 echocardiograms at Mayo Clinic. SV systolic function was assessed using echo-derived ejection fraction (Echo_EF) at baseline, and annually for 3 years. Temporal decline in SV systolic function was estimated as relative change (relative Δ_Echo_EF)/year. Exploratory analysis was performed to assess the effect of guideline-directed medical therapy (GDMT) on Echo_EF. Results: Of 414 patients (age 27 ± 9 years; males 228 [55 %]), 287 (69 %) and 127 (31 %) had dominant morphologic left ventricle (LV) and right ventricle (RV), respectively. Assessment of Echo_EF was feasible in 1464 of 1603 echocardiograms (91 %). The baseline Echo_EF was 54 % (48-58), and the relative Δ_Echo_EF was -3.9 % (95 %CI -6.3 to -2.5 %)/year. The predictors of progressive SV systolic dysfunction were older age, morphologic RV, ≥moderate atrioventricular valve regurgitation, cardiac implantable electronic devices, and atrial fibrillation. Progressive SV systolic dysfunction was associated with an approximately 2-fold increase in death/transplant (hazard ratio 1.92, p = 0.009), independent of baseline Echo_EF and comorbidities. GDMT was associated with improvement in Echo_EF in patients with morphologic LV. Conclusions: The current study underscores the importance of longitudinal echocardiographic monitoring of SV systolic function, and the potential clinical benefits of GDMT in patients with morphologic LV. Further studies are required to determine whether interventions such as valve surgery, rhythm control strategy, and physiologic pacing would prevent or reverse SV systolic dysfunction.