Isolated Foetal Cardiac Asymmetry as a Predictor of Postnatal Coarctation of the Aorta

Background: Foetal cardiac asymmetry with no other intra-cardiac abnormality may be an indicator of postnatal coarctation of the aorta (CoAo). Our aim was to assess the sensitivity and specificity of isolated foetal cardiac asymmetry as a predictor of CoAo. Method: This was a retrospective study of all foetal echocardiograms performed at the sole foetal cardiology service in Western Australia from 2001 to 2010 with the finding of isolated significant discrepancy between the size of the right and left heart chambers as defined by tricuspid:mitral valve dimension ratio (Tv:Mv) or pulmonary:aorta ratio (Pa:Ao) ≥1.2 excluding univentricular heart and other congenital intra-cardiac malformations except LSVC to coronary sinus. All findings were compared to postnatal echocardiography. Results: There were 21 cases identified between 19 and 37 weeks gestation, median 27. Of these Group 1 (n = 10) had CoAo confirmed on post-natal echocardiography, Group 2 (n = 11) did not have CoAo. Group 1 Tv:Mv range = 1.5–2.3, mean 1.7 compared to Group 2 Tv:Mv = 1.2–1.6, mean 1.4 (P < 0.002). Group 1 Pa:Ao range = 1.2–2.5 mean 1.6 was not significantly different to Group 2 range = 1.1–2.2 mean 1.5 (P = 0.53). The Tv:Mv of 1.6 or greater has present in 7 of 10 with CoAo and only 1 in Group 2 (sensitivity 70%, specificity 91%). Conclusion: Foetal cardiac asymmetry with the Tv:Mv of 1.6 or greater in the absence of other cardiac structural abnormalities by fetal echocardiography is a good predictor of post-natal CoAo.