Suboptimal Interrater Reliability Limits Predictive Value of Fetal Echocardiography for Neonatal Balloon Atrial Septostomy in Fetuses With Dextro-Transposition of the Great Arteries.

Introduction: Neonates with dextro-transposition of the great arteries (d-TGA) require adequate mixing at the atrial level. Without this, they experience severe cyanosis, necessitating balloon atrial septostomy (BAS). Multiple studies have identified various fetal echocardiogram (FE) findings as risk factors for postnatal BAS. The predictive value of these findings remains poor in clinical use.

Hypothesis: We aimed to determine the relationship between interrater reliability (IRR) of FE BAS predictors and postnatal BAS, as well as postnatal markers of hypoxia/hypoxemia. We hypothesized that poor IRR may contribute to limited FE predictive value.

Methods: We identified d-TGA pregnancies followed at our institution between 2012 and 2022, excluding fetuses with large ventricular septal defects and pregnancies terminated or lost to follow-up. Two groups of 3 independent readers blinded to BAS outcome assessed 7 FE predictors: peak pulmonary vein Doppler velocity >41 cm/sec, reverse flow in patent ductus arteriosus (PDA), restrictive PDA, restrictive patent foramen ovale (PFO), bidirectional PFO flow, flat septum primum, and hypermobile septum primum. Interrater reliability was determined with the S metric. Clinical information before BAS was collected to evaluate postnatal physiology. A multivariable logistic regression was used to determine significant associations between FE findings and postnatal BAS. Multivariable linear regressions were also used to determine significant associations between FE findings and indicators of hypoxia/hypoxemia.

Results: Fifty-two fetuses were included, of whom 25 (48%) underwent BAS. Fetal echocardiograms were performed at a mean gestational age of 34.02 weeks (SD = 2.14 weeks). Interrater reliability was lowest for PFO flow direction and highest for restrictive PDA, likely due to its rarity. The remainder of FE predictors had either moderate or substantial IRR. Five FE characteristics could be included in the regression analysis, and none were significantly associated with odds of BAS, postnatal pH, or postnatal oxygen saturation. Reverse PDA flow was statistically significantly associated with lower postnatal pre-BAS paO.

Conclusions: Our results demonstrate substantial but not excellent IRR for current FE BAS predictors. There was no significant association between these predictors and postnatal BAS or postnatal hypoxia/hypoxemia in d-TGA patients, except for reverse PDA flow and lower postnatal paO. Additional work is needed to identify more reliable FE predictors of postnatal d-TGA physiology.