Abstract Body (Do not enter title and authors here): Background: In patients with Fontan palliation, ejection fraction (EF) and global longitudinal strain (GLS) are associated with exercise capacity and survival. We investigated the associations between EF and GLS on echo and 4-dimensional phase contrast (4DF) cardiac MRI (CMR) parameters, including percent collateral flow (%CF).
Methods: Single-center, retrospective review of patients post-Fontan who underwent CMR in 2023 and echocardiogram within 1 year. GLS was measured on echo in the apical 4-chamber view. %CF and regurgitant fractions were measured using 4DF. Indexed ventricular end-diastolic (iEDV) and end-systolic (iESV) volumes and EF were also measured. Descriptive data are presented as median (Q1 – Q3). Spearman correlation was used to compare continuous variables. Linear regression analysis was performed to quantify the relationship between GLS and predictor variables.
Results: Thirty-two patients met inclusion and exclusion criteria. Of the 32 patients in the study cohort, 40.6% were females and 75% had a systemic right ventricle. Median age at CMR was 16.6 (12.1 – 20.0) years, median duration between echo and CMR was 49.5 (2 – 95) days. There was moderate to high correlation between GLS and iEDV, GLS and iESV, and GLS and EF. There was no significant association between %CF and GLS, and %CF and EF (table). Moderate or severe valve regurgitation was present in 12 (38%) patients. When excluding these patients, GLS had a moderate correlation with %CF, EF, iEDV, and iESV (table). Multivariable linear regression analysis was performed to test if a combination of CMR parameters could best predict GLS. EF and %CF, remained associated with GLS. The overall regression was statistically significant (R2 = 0.5, F(2, 17) = 8.75, p = .002).
Conclusion: In this pilot cohort of Fontan patients, worse (less negative) GLS% was associated with larger iEDV and iESV. There was also an association between GLS and higher %CF when excluding patients with more than mild valve regurgitation. This relationship may be mediated by volume load of collateral flow on the heart. These data may provide evidence of an early impact of %CF burden and resultant volume overload on ventricular contractility.