Prognostic Value of Cardiac MRI-derived Left Atrial and Biventricular Function in Children with Repaired Tetralogy of Fallot.

Purpose To evaluate whether left atrial (LA) function assessed with cardiac MRI provides incremental prognostic value beyond biventricular function in children with repaired tetralogy of Fallot (rTOF). Materials and Methods In this prospective study, pediatric participants with rTOF were consecutively recruited between August 2019 and December 2021 and healthy controls from July 2017 to August 2018. All participants underwent cardiac MRI. Measurements included LA size, ejection fraction (EF), strain, and strain rate across reservoir, conduit, and pump phases, and biventricular volumes, mass, and global longitudinal strain (GLS). Late gadolinium enhancement was assessed in rTOF. End point events were heart failure hospitalization and reoperation. Cox regression analysis was performed. Model performance was assessed using Harrell concordance index, integrated discrimination improvement, and net reclassification improvement. Results Seventy-eight participants with rTOF (mean age, 10.73 years ± 3.66 [SD]; 47 male) and 30 controls (mean age, 11.06 years ± 2.97; 21 male) were included. Compared with controls, participants with rTOF demonstrated LA dysfunction, with lower reservoir EF, strain, and strain rate, lower conduit EF and strain, and higher pump EF, while biventricular GLS remained normal. Over a median follow-up of 2 years, impaired LA conduit strain (<15.83%), impaired right ventricular (RV) GLS (<22.66%), and higher end-systolic volume index were independently associated with end point events (hazard ratio = 4.72, 2.75, and 1.02, respectively). Adding impaired LA conduit strain into the RV GLS model increased the concordance index from 0.74 to 0.82 (P < .001) with an integrated discrimination improvement of 0.13 (P = .006) and net reclassification improvement of 0.89 (P < .001). Conclusion In pediatric rTOF with preserved ventricular EF and GLS, LA dysfunction at cardiac MRI was evident. Incorporating LA conduit strain alongside established RV functional parameters improved prognostic assessment during follow-up. Keywords: Pediatrics, MR Imaging, Cardiac, Left Atrium, Right Ventricle, Congenital, Outcomes Analysis, Cardiac MRI, Congenital Heart Disease, Tetralogy of Fallot, Left Atrial Function Supplemental material is available for this article. © RSNA, 2026.