How Aortic Arch Views Sharpen Prenatal Coarctation Care

How Aortic Arch Views Sharpen Prenatal Coarctation Care

Indeed, fetal cardiologists frequently face clinical uncertainty when evaluating suspected aortic coarctation. Consequently, achieving an accurate prenatal coarctation diagnosis remains one of fetal echocardiography's greatest challenges. In particular, traditional screening often yields high false-positive rates because the patent ductus arteriosus masks arch narrowing before birth. However, a new multicenter cohort study now provides practical clarity. Specifically, the study evaluates ten published sagittal aortic-arch parameters and validates an improved multivariable predictive model.

Improving Prenatal Coarctation Diagnosis with Sagittal Imaging

Prenatal detection allows planned delivery at specialized tertiary centers where neonatologists can initiate early prostaglandin infusions. However, false-positive findings cause substantial maternal anxiety and unnecessary transfers. Therefore, investigators at two tertiary referral centers in Thailand conducted a retrospective diagnostic study across an 11-year period.

The team reviewed offline sagittal aortic-arch videoclips from 154 fetuses with suspected coarctation. A single expert blinded to the final postnatal outcomes re-examined ten published echocardiographic parameters. Overall, postnatal follow-up confirmed neonatal coarctation of the aorta in 82 infants (53.2%).

Key Echocardiographic Markers and Diagnostic Performance

Univariate analysis revealed several notable anatomical distinctions between true-positive and false-positive cases. First, fetuses with confirmed coarctation demonstrated a significantly longer distance between the left common carotid artery and left subclavian artery. The median distance reached 3.12 mm in confirmed cases compared with 2.14 mm in unaffected fetuses. Furthermore, the characteristic shelf sign appeared far more frequently in affected neonates, presenting in 74.4% versus 50.0% of cases.

Among individual parameters, the carotid-subclavian artery index achieved the highest discriminatory accuracy with an area under the curve of 0.684. However, single markers offered insufficient precision for definitive counseling. Consequently, the researchers developed a parsimonious multivariable logistic regression model. This refined model incorporated four parameters: the interarterial distance, subclavian diameter, descending aortic diameter, and the shelf sign.

Clinical Impact and Practical Application for Specialists

The combined predictive model demonstrated superior discriminatory capability, reaching an area under the curve of 0.749. Moreover, applying a predicted probability threshold of 0.45 achieved a clinical sensitivity of 84.1% and a specificity of 54.2%. Thus, this multiparametric approach effectively filters out nearly half of false-positive referrals while capturing over four-fifths of critical cases.

For obstetricians and pediatric cardiologists, adopting these sagittal metrics can substantially refine risk stratification. Specifically, when clinicians identify an elongated carotid-subclavian space, an increased subclavian diameter, and an aortic shelf sign, vigilance must increase. Conversely, borderline isolated findings warrant careful serial assessment rather than immediate aggressive intervention.

Frequently Asked Questions

Q1: Why is prenatal detection of coarctation of the aorta challenging?

In utero, the widely open ductus arteriosus diverts blood flow away from the aortic isthmus, which conceals anatomical narrowing and results in frequent false positives.

Q2: Which single parameter showed the best diagnostic accuracy in this study?

The carotid-subclavian artery index showed the highest individual accuracy, achieving an area under the receiver operating characteristic curve of 0.684.

Q3: What variables form the new multivariable predictive model?

The final predictive model combines the left common carotid-to-left subclavian artery distance, left subclavian artery diameter, descending aortic diameter, and presence of the shelf sign.

References

1. Chonnak U et al. Sagittal aortic-arch assessment for prenatal diagnosis of coarctation of the aorta: comparative evaluation of 10 published methods and a new predictive model. Ultrasound Obstet Gynecol. 2026 Sep 19. doi: 10.1002/uog.70321. PMID: 42762540.
2. Tuo G, Paladini D, Marasini L, et al. Fetal aortic coarctation: A combination of third-trimester echocardiographic parameters to improve the prediction of postnatal outcome. Front Pediatr. 2022;10:866994.
3. Ming H, Zhao B, Shi H, et al. Accurate prenatal diagnosis of coarctation of the aorta by 3-step echocardiographic diagnostic protocol. BMC Pediatr. 2024;24(1):545.