Quantification of tricuspid valve regurgitation with 4D flow MRI: evaluation of different methods in patients with Ebstein's anomaly

Abstract Objectives Ebstein's anomaly (EA) is a congenital heart disease involving a dysplasia of the tricuspid valve, the right atrium and the right ventricle. Its imaging hallmark is the apical displacement of the septal leaflet of the tricuspid valve. A severe tricuspid regurgitation (TR) is common in this population and the surgical correction of this condition aims to minimize the regurgitation. Several methods are used to quantify the regurgitant volume (RVol) and fraction (RF). 4D-flow MRI is now part of the daily clinical practice in congenital heart disease, with applications in shunt quantification, assessment of pulmonary or aortic valve regurgitation. However, data on the evaluation of TR in patients with EA is scarce. Our aim was to evaluate different methodology in 4D-flow MRI to quantify TR in adult with EA. Methods Clinical data and imaging data of cardiac magnetic resonance including 4D-flow of 31 patients with EA where retrospectively analysed. The tricuspid RVol was assessed with 3 different methods (Figure 1a): First, the 2D-indirect method consisted in the subtraction of the systolic forward volume through the main pulmonary artery acquired with 2D-phase contrast from the right ventricular stroke volume (RVSV) calculated with the systolic and diastolic difference of ventricle volume with Simpson’s method on short axis steady-state free-precession 2D-images stack. Second the 4D-indirect method consisted in the subtraction of the of the systolic forward volume through the main pulmonary artery acquired with 4D flow- from the diastolic forward volume through the tricuspid valve tracked along the cycle with 4D-flow. Third, the RVol was directly measured in the systolic regurgitant jet in right atrium using 4D flow. The reference was defined as the mean value of those 3 methods. Correlation was performed for each of the 3 methods with the reference method. Results Baseline characteristics, including BNP values and VO2 max can be found in the fig. 1b. Pearson correlation coefficient (r) and p-value were found for the linear regression of the following combination: 4D-direct vs 4D-indirect: r=0.82, p=0.001; 4D-direct vs 2D method: r=0.87, p=0.001; 4D-indirect vs 2D method: r=0.79, p=0.001; 2D method vs mean 3 methods: r=0.93, p=0.001; 4D indirect method vs mean 3 methods: r=0.93, p=0.001; 4D indirect method vs mean 3 methods, r:0.95, p=0.001; Bland altman and linear regression can be found in fig. 2. Conclusion The best agreement with the reference method was found for the 4D-direct method. The assessment of the RVol through the direct measurement the regurgitant jet seems to be promising and paves the way to its evaluation in larger cohort with long-term follow-up Bland Altman