Bryan H. Goldstein

Background In Fontan circulation, diastolic dysfunction portends a worse clinical outcome but may be concealed during routine assessment. Invasive evaluation with rapid volume expansion (RVE) can identify patients with occult diastolic dysfunction (ODD). We sought to evaluate the association between ODD and adverse clinical outcomes at medium‐term follow‐up. Methods and Results We conducted a single‐center observational study of patients with Fontan circulation who underwent clinical catheterization with RVE from 2012 to 2017. ODD was defined as post‐RVE end‐diastolic pressure ≥15 mm Hg. A composite adverse clinical outcome included mortality, cardiac transplant, ventricular assist device, plastic bronchitis, protein‐losing enteropathy, arrhythmia, stroke/thrombus, or cardiac‐related hospital admission. Proportional hazards regression was used to compare the ODD‐positive and ODD‐negative groups for risk of the composite adverse clinical outcome. Eighty‐nine patients with Fontan circulation (47% female patients) were included at a median age of 14 years. ODD was identified in 31%. Fontan duration was longer in the ODD group ( P =0.001). The composite adverse clinical outcome occurred more frequently in the ODD group (52 versus 26%, P =0.03) during a median follow‐up duration of 2.9 years after catheterization. ODD (hazard ratio [HR], 2.68 [95% CI, 1.28–5.66]; P =0.02) and Fontan duration (HR, 1.07 [95% CI, 1.02–1.12]; P =0.003) were associated with the composite adverse clinical outcome. When stratified by Fontan duration, ODD remained significantly associated with the hazard of adverse clinical outcomes in patients with a Fontan duration ≥10 years (HR, 2.57 [95% CI, 1.03–6.57]; P =0.04). Conclusions Cardiac catheterization with rapid volume expansion reveals a significant incidence of ODD, which relates to Fontan duration. ODD is associated with an increased hazard of adverse clinical outcomes during medium‐term follow‐up, especially in patients with longer Fontan duration. ODD may portend a worse prognosis in Fontan circulation.