Defining Diastolic Dysfunction Post-Fontan: Threshold, Risk Factors, and Associations with Outcomes

Abstract

BACKGROUND: Following the Fontan procedure, patients with single ventricle physiology are at high risk of diastolic dysfunction (DD) and elevated end-diastolic pressure (EDP). OBJECTIVE: This study aims to determine (1) the optimal EDP threshold correlated with adverse outcomes post-Fontan and (2) the clinical and imaging predictors of DD. METHODS: The study included patients from the Fontan Outcome Registry using CMR Examinations (FORCE) who underwent cardiac catheterization and cardiac magnetic resonance (CMR) within a two-year window. The composite outcome was defined as all-cause mortality, sustained atrial or ventricular arrhythmia, plastic bronchitis, protein-losing enteropathy, or listing for transplantation. The EDP cutoff was determined using the lowest Brier score from Cox proportional hazard models. RESULTS: The study included 861 patients (mean age 16.4 ± 9.3 years). Mean EDP was 9.0 ± 3.5 mm Hg, with DD defined at an optimal EDP threshold \u3e13 mm Hg. Patients were followed for a median of 3.6 years after catheterization. By univariable analysis patients with DD were more likely to have Fontan associated liver disease (40% vs 29%, p=0.03) and kidney disease (19% vs 6%, p\u3c0.001). In multivariable analyses, DD was associated with the composite outcome (HR 3.37, 95% CI: 2.03-5.59, p\u3c0.001). Ninety-seven patients (11.3%) had DD. Multivariable analysis demonstrated that older age at catheterization, greater body mass index (BMI), non-left ventricular morphology, and higher ventricular end-diastolic volume (EDV) were associated with DD. CONCLUSION: DD, defined as an EDP \u3e13 mm Hg, is linked to over threefold higher risk of adverse outcomes. Risk factors for DD include older age, higher BMI, non-left ventricular morphology, and larger EDV. The presence of risk factors may warrant screening catheterization to identify DD and modify care accordingly