Interpreting the MV / TV ratio in fetal transposition with coarctation: Implications for counseling

to 1.17, and the authors note that CoA in TGA is easily missed in late gestation.Does the cutoff hold for families first seen late? IN CREMENTAL VALUEEven in suspected isolated CoA, ventricular disproportion alone is only moderately accurate (MV/TV <0.71, i.e., TV/MV >1.4: sensitivity 72.6%, specificity 65.4%).3 In our experience, its degree and arch geometry, rather than a single threshold, shape what we tell families.In transposition physiology, aortic measurements have also predicted arch repair; 4 in the authors' series, the isthmus-todescending aorta ratio separated the groups (0.50 vs 0.80).A combined model, with interobserver reproducibility data, would show how they complement each other. CON CLUS IONThe authors rightly name prenatal counseling among the main beneficiaries of their finding, and themselves describe the cutoff as a supportive indicator rather than a definitive threshold.For parents already facing a TGA diagnosis, a suspected CoA means a more complex operation and a different expected course.The ratio should therefore be shared with them not as a second diagnosis, but as an uncertainty that birth may not fully resolve: in this series, three CoAs presented between the second and fourth month.I congratulate the authors on giving the fetal cardiology community a simple and promising marker, whose validation will require multicenter collaboration.