Usefulness of Pulmonary Arterial End-Diastolic Forward Flow Late After Tetralogy of Fallot Repair to Predict a “Restrictive” Right Ventricle

The functional significance of pulmonary arterial end-diastolic forward flow (EDFF) in patients with repaired tetralogy of Fallot (rTOF) is not fully understood with conflicting reports regarding its associations with pulmonary regurgitation (PR), right ventricular (RV) size and function, and so-called ‘restrictive’ RV physiology. To examine these associations, we retrospectively analyzed 399 patients with rTOF who had contemporaneous echocardiography (Echo) and cardiovascular magnetic resonance (CMR) studies. The median age at TOF repair was 0.7 years [0.21, 2.66], age at CMR was 19.8 years [13.0, 29.4], and interval between Echo and CMR was 48 days [0, 182]. Doppler identified EDFF in 122 (31%) patients and CMR in 113 patients (28%). Compared with those without EDFF, patients with EDFF were younger, had greater PR, and higher RV end-diastolic volume (EDV), stroke volume, and ejection fraction. Markers of RV restriction such as right atrial size did not differ between groups. On multivariable regression, EDFF was associated with higher RV stroke volume and lower LV EDV. The association between Echo and CMR measurements of EDFF was modest (area under the ROC curve = 0.684, r = 0.374, p <0.001). In conclusion, EDFF was common in this large cohort of rTOF patients, but its presence and extent varied between Echo and CMR. EDFF was associated with greater PR and larger RV size but not with markers of poor RV compliance such as right atrial enlargement. Mechanisms beyond RV noncompliance may contribute to the presence of EDFF.