Prediction of coarctation of the aorta in fetuses with transposition of great arteries: Inverted ventricular discrepancy as a predictor of arch repair in TGA.

Abstract

Introduction: Transposition of great arteries (TGA) with coarctation of the aorta (CoA) is a rare association but increases surgical complexity and worsens outcomes. Despite improvements in prenatal diagnosis, CoA remains difficult to diagnose before birth. Fetal ventricular discrepancy is a predictor of CoA in normal cardiac anatomy, and the smaller the mitral valve/ tricuspid valve (MV/TV) annulus diameters ratio, the higher the probability of CoA after birth. The aim of this study was to describe the features of MV/TV ratio in fetuses with TGA and CoA and to explore its predictive value for CoA and aortic arch repair at birth.

Material and methods: This is a retrospective study at a tertiary center. We selected all cases of TGA from January 2011 to December 2024 excluding complex and/or associated anomalies. We reviewed all fetal echocardiograms available and, at the first diagnostic exam, we measured MV, TV, aortic valve (AV) and pulmonary valve (PV) annulus diameters, and MV/TV and AV/PV ratios were calculated. Transverse aortic arch, isthmus, descending aorta, and ductus arteriosus diameters were measured. We reviewed post-natal diagnosis and surgical reports. Follow-up was extended until the first year of age in terms of aortic re-coarctation, late diagnosis of CoA and reoperations.

Results: We identified 188 TGA, among which 19 (10%) had CoA. TGA/VSD were 34 (18%) and TGA/IVS 154 (82%). Among the 136 prenatally diagnosed, 11 had CoA (8%). MV/TV ratio was higher in TGA/CoA group than in isolated TGA group (p < 0.001) and AV/PV ratio was smaller in TGA/CoA compared to isolated TGA (p < 0.001). ROC analysis was performed for the MV/TV ratio discriminating fetuses with TGA/CoA. A cut off value of 1 yielded a sensitivity of 100% and a specificity of 91.5% (AUC 0.99, p < 0.001).

Conclusions: We confirmed that the RV is smaller in TGA/CoA than in TGA alone; thus, the ventricular discrepancy is in favor of the LV. MV/TV ratio is a good predictor of CoA in fetuses with TGA, and a cutoff of 1 can be used to discriminate neonates at need for arch repair after birth.