Toward Improving the Fetal Diagnosis of Coarctation of the Aorta

Coarctation of the aorta (CoA) is the most common ductal-dependent lesion missed on neonatal exam screening. Prenatal diagnosis of CoA improves outcomes through early initiation of prostaglandin. Fetal echocardiographic parameters including 2D and Doppler findings have been studied as predictive measures for fetal diagnosis of CoA, but diagnosis rates remain variable. A comprehensive set of predictor variables was applied to fetuses suspected of CoA to analyze which parameters were associated with postnatal CoA. UCSF Fetal Cardiovascular Program databases were queried for fetuses suspected of CoA (2008-2014). Retrospective measurements of aorta/pulmonary artery ratio (AoPA), LV/RV ratio, ascending aorta Z-score (AscAo), isthmus Z-score, isthmus/duct ratio (I/D), posterior "shelf" of descending aorta, and diastolic flow persistence at the isthmus were recorded. ROC analysis identified the parameters most predictive of postnatal CoA. Among 97 fetuses with probable CoA, 62 had complete follow-up. Of these fetuses, 45 (72.5%) had postnatal confirmation of CoA and 17 did not have CoA. The parameters most predictive of postnatal CoA included AscAo, isthmus Z-score, and I/D, with respective AUC of 0.80, 0.89, and 0.90. Diastolic flow persistence was seen more often in fetuses with postnatal CoA, but did not reach statistical significance. Combining 2D and Doppler criteria (AoPA < 0.65 or diastolic flow persistence) improved sensitivity to 87%, but introduced several false positives. Isthmus imaging and AoPA ratio are useful predictors of CoA. Doppler information was most helpful when 2D imaging was equivocal; its addition resulted in high sensitivity in an enriched cohort referred for fetal echocardiography.