Atrial Right-to-Left Shunting After Tetralogy of Fallot Repair Is Associated With Improved Atrial Function and Shorter Hospital Length of Stay: An Echocardiographic Cohort Study.

Background: Atrial right-to-left (aRL) shunting is often identified on echocardiography in the early postoperative period following repair of tetralogy of Fallot (TOF) and is thought to reflect poor right ventricular (RV) compliance but to be possibly beneficial in serving as a "pop-off" for the right ventricle. The aim of this study was to investigate the relationship between aRL shunting and echocardiographic diastolic function and early postoperative outcomes, hypothesizing that aRL shunting would be associated with worse diastolic function and with postoperative length of stay (LOS).

Methods: A single-center cohort study was conducted among patients who underwent repair of TOF. Echocardiograms were obtained 2 to 5 days after repair. Patients were grouped as "elective" if repaired after 30 days of age without prior palliation, "staged" if they underwent neonatal palliation before repair, or "neonatal" if repaired at <30 days age. aRL shunting was compared with all others: bidirectional, left-to-right shunt, and no atrial shunt detected. Linear regression tested the relationship of aRL shunting with right atrial volumes and right atrial emptying fraction (RAEF), RV inflow and tissue Doppler velocities, and RA peak longitudinal strain and early strain rate. Multivariable negative binomial regression was conducted to test the association between aRL shunting and LOS, stratified by repair group.

Results: There were 197 patients with TOF (60% male, 74% white): (127 [64%]) underwent elective repair, 41 (21%) staged repair, and 29 (15%) neonatal repair. aRL shunting was present in 68 patients (35%). In the overall cohort, aRL shunting was associated with lower right atrial end-diastolic volume, higher RAEF, higher A-wave peak velocity, and higher right atrial peak longitudinal strain. In the subgroup analysis, aRL shunting was associated with higher RAEF and peak longitudinal strain in the elective repair group only, in which aRL shunting was also associated with shorter LOS.

Conclusions: aRL shunting after TOF repair is associated with better atrial function and possibly with a combination of robust atrial function in the presence of RV noncompliance and shorter LOS in patients undergoing elective TOF repair, but not in those undergoing neonatal intervention.