Utility of Single Ventricle Longitudinal Strain and Evaluation of its Clinical Implications in Patients with Fontan Circulation

While numerous risk factors for poor outcomes in Fontan patients have been investigated, much remains unknown about potential predictors of clinical well-being or long-term morbidity. Additionally, accurate non-invasive assessment of single ventricle (SV) systolic and diastolic function has remained elusive, making it even more difficult to evaluate cardiac performance as a determinant of patient outcome. Our study aimed to evaluate the relationship between SV longitudinal strain (SV-LS) measured via speckle-tracking echocardiography and several markers of clinical status. This was a retrospective study of Fontan patients with an echocardiogram at the Medical University of South Carolina from August 2022 to July 2023. SV-LS and other echocardiographic parameters were obtained and evaluated along with laboratory values, exercise test measures, cardiac catheterization data, and clinical outcomes. Bivariate tests of association were used to determine statistically significant relationships. 105 patients were included. SV-LS was associated with percent predicted VO2 max (p = 0.034). ROC analysis identified an SV-LS cutoff of –17.5% (AUC = 0.67, sensitivity 75%, specificity 62%) for detecting reduced exercise capacity. Echocardiographic indices of ventricular function including ejection fraction (r= –0.49) and fractional area change (r= –0.48) (p < 0.0001) correlated with SV-LS. There were no significant associations between SV-LS and laboratory measures of end-organ function, cardiac catheterization data, or adverse clinical events including transplant listing or protein-losing enteropathy. SV-LS is a non-invasive echocardiographic measure that may be associated with exercise capacity and has the potential to be a useful tool for primary cardiologists caring for this growing cohort of patients.