Fetal RFOF Mimics CoA: The Predictive and Differential Value of Cardiac Output and Left Heart Morphological...

Studies have confirmed that a RFOF (redundant foramen ovale flap) can mimic CoA (coarctation of the aorta) in terms of traditional indicators; however, there is currently no more comprehensive and feasible indicator to differentiate between the two. This study aims to investigate the effect of RFOF on cardiac output, and explore the ability of multiple left cardiac parameters to differentiate RFOF from CoA.

This prospective diagnostic cohort study consecutively enrolled fetuses with suspected CoA and normal controls. Comprehensive echocardiographic measurements, including cardiac output and novel morphological parameters-including RCO/LCO (right cardiac output/left cardiac output), the FOFd/LAd (foramen ovale flap/left atrial diameter ratio), aortic arch angle, and LIOA (left ventricular inflow-outflow tract angle)-were performed by operators blinded to the postnatal outcome. ROC (Receiver operating characteristic) curve analysis was performed to evaluate the predictive ability of all indicators for pregnancy outcomes.

Analysis revealed that in the RFOF Group, FOFd/LAd had the highest AUC (area under the curve), followed by RCO/LCO. In the CoA Group, the aortic isthmus/ductus arteriosus diameter (Aoi/DA) and aortic arch angle showed the highest AUC values.

RFOF can mimic the ultrasonic manifestations of CoA in terms of traditional indicators. FOFd/LAd > 0.65 (AUC = 1.000) is identified as a specific marker for RFOF, while RCO/LCO > 1.60 (AUC = 0.966) provides strong supportive evidence. Conversely, an aortic arch angle > 75.84° receiver operating characteristic (AUC = 0.995) combined with Aoi/DA < 0.75 (AUC = 0.999), suggests a higher probability of CoA. FOFd/LAd, aortic arch angle, and LIOA can help distinguish between RFOF and CoA.

What's already known about this topic? The established consensus indicates that RFOF can mimic the sonographic features of CoA prenatally by causing imbalances in traditional parameters of cardiac chamber dimensions and great vessel diameter ratios. However, reliable tools for prenatally distinguishing between these two conditions based on hemodynamic and left heart morphological characteristics remain unavailable. What does this study add? This study adds a new, multiparameter approach that combines hemynamic (RCO/LCO) and novel morphological (FOFd/LAd, Aortic Arch Angle, LIOA) assessments. This approach moves beyond the limitations of traditional ratios and provides clinicians with practical tools to reduce the false positive diagnosis of CoA in fetuses with RFOF.