Abstract 20985: The Aortic Isthmus-Ductal Angle, a Novel Predictor of Coarctation of the Aorta in the Fetus
Background: Neonatal coarctation of the aorta is common. Reducing false positive rates in the fetus has been difficult and remains an important challenge in prenatal diagnosis. We studied diagnostic accuracy of a novel ultrasound-derived angle as predictor of coarctation in the fetus.
Methods: Prenatal cardiac scans from 36 fetuses with suspected coarctation (20 had, 16 did not; 78 images) were reviewed retrospectively. Scan data were obtained from 353 normal fetuses. In all, the aorta was imaged in sagittal view using power Doppler, e-Flow or high-definition colour flow. The ‘Aortic Isthmus-Ductal Angle' (AIDA) was measured in all 431 images, at the expected site of coarctation. Three observers, one blinded to outcome, measured AIDA in the diagnostic population (36 suspected cases, 78 controls; 156 images). The diagnostic accuracy of AIDA was estimated and receiver-operating characteristic (ROC) curves obtained (for blinded observer). Regression models were used to determine its relationship with gestational age. Sensitivity and specificity of various thresholds of AIDA were calculated. Intra and inter-observer reliability was assessed.
Results: AIDA was narrower in fetuses with coarctation (mean ± SD 137° ± 24°) than in cases without (‘asymmety group', mean ± SD 183° ± 13°) and in controls (mean ± SD 187° ± 10°) (P < 0.001). Using a threshold of 150°, sensitivity was 85% (95% CI 62-97%) and specificity was 100% (95% CI 79-100%). The area under the ROC curve was 0.9344. In normals, there was a statistically significant (but small) relationship between gestational age and AIDA. The figure shows a scatterplot in the diagnostic population with line of best fit. Average intra-observer differences and differences between each pair of observers was <5° in all cases.
Conclusion: AIDA predicted coarctation with reasonable sensitivity and excellent specificity in this study. Measuring AIDA during fetal echocardiography could substantially reduce false positive rates.
- © 2010 by American Heart Association, Inc.