Is biventricular vascular coupling a better indicator of ventriculo-ventricular interaction in congenital heart disease?

Background: Ventriculo-ventricular interactions are known to exist, though not well quantified. We hypothesised that the ventricular-vascular coupling ratio assessed by cardiovascular MRI would provide insight into this relationship. We also sought to compare MRI-derived ventricular-vascular coupling ratio to echocardiography and patient outcomes.
Methods: Children with cardiac disease and biventricular physiology were included. Sanz's and Bullet methods were used to calculate ventricular-vascular coupling ratio by MRI and echocardiography, respectively. Subgroup analysis was performed for right and left heart diseases. Univariate and multivariate regressions were performed to determine associations with outcomes.
Results: A total of 55 patients (age 14.3 ± 2.5 years) were included. Biventricular ventricular-vascular coupling ratio by MRI correlated with each other (r = 0.41; p = 0.003), with respect to ventricle's ejection fraction (r = -0.76 to -0.88; p < 0.001) and other ventricle's ejection fraction (r = -0.42 to -0.47; p < 0.01). However, biventricular ejection fraction had only weak correlation with each other (r = 0.31; p = 0.02). Echo underestimated ventricular-vascular coupling ratio for the left ventricle (p < 0.001) with modest correlation to MRI-derived ventricular-vascular coupling ratio (r = 0.43; p = 0.002). There seems to be a weak correlation between uncoupled right ventricular-vascular coupling ratio with the need for intervention and performance on exercise testing (r = 0.33; p = 0.02).
Conclusion: MRI-derived biventricular ventricular-vascular coupling ratio provides a better estimate of ventriculo-ventricular interaction in children and adolescents with CHD. These associations are stronger than traditional parameters and applicable to right and left heart conditions.