Measuring Atrioventricular Valve Regurgitation in Fontan Patients Using Cardiac MRI and the Association with Clinical...

Atrioventricular valve regurgitation (AVVR) predicts long-term post-Fontan adverse outcomes. Literature on the measurement and prognostic value of quantitative AVVR assessment using cardiac magnetic resonance imaging (CMR) is limited. This study compared echocardiographic AVVR measurements with measurements by CMR, and investigated their association with clinical outcomes using the multi-center Fontan Outcome Registry using CMR Examination (FORCE).

Patients with an examiner-reported AVVR severity category from CMR (AVVR_Report-Cat) and an AVVR from matched echocardiography (AVVR_Echo) were included. Three quantitative CMR AVVR regurgitant fraction were used: (1) stroke volume and antegrade aortic flow (AVVR_Standard), (2) atrioventricular valve flow and antegrade aortic flow (AVVR_AVV-AO), and (3) examiner-reported regurgitation fraction (AVVR_Report-RF). Moderate AVVR was defined as regurgitant fraction of 20-40% and severe >40%. The concordance across methods was calculated using Kappa statistics, and associations with outcomes of mortality or listing for/receiving heart transplantation were analyzed using Cox proportional hazard models. C-statistic was used to compare model performance.

2,309 Fontan patients were included, with a median age at CMR of 15.7 years and 42.1% female. Categorical AVVR severity reported by CMR was significantly associated with adverse outcomes (adjusted HR 2.10, 95% CI [1.38, 3.19] for moderate and 4.61 [2.80, 7.58] for severe AVVR), comparable to AVVR reported by echocardiography. AVVR_AVV-AO showed stronger concordance with AVVR_Report-Cat (Kappa=0.58) and higher hazards of the adverse outcome than AVVR_Standard. The subset of patients with examiner-reported regurgitation fraction (AVVR_Report-RF) showed the highest hazard associated with AVVR and the highest C-statistic among all methods including echocardiography.

This is the first study evaluating different CMR measurements of AVVR in a large cohort of Fontan patients. Compared with AVVR_Standard, AVVR_AVV-AO had higher concordance with the reported categorical AVVR using CMR. Moderate and severe AVVR determined by both CMR and echocardiography were associated with comparably increased hazards of adverse clinical outcomes.