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Transcatheter intervention modestly improves aortic flow, LV function in patients with mild coarctation
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Transcatheter intervention can effectively decrease the transcoarctation pressure gradient in patients with mild coarctation of the aorta, but this appears to yield only a modest improvement in aortic hemodynamics and does not equal a reduction in myocardial strain, according to recent findings.
In the retrospective clinical study, researchers evaluated 34 patients (mean age, 41 years; range, 22-61) with coarctation of the aorta (COA) who were referred for transcatheter intervention to Massachusetts General Hospital between 2006 and 2014.
The researchers used patient-specific hemodynamic input measures to formulate a computational fluid dynamics and lumped parameter modeling framework. This framework was validated with patient-specific outcomes predictive of left ventricular function and aortic hemodynamics in the patients before and after intervention.
Patients underwent catheterization to determine the morphology and pressure gradient of the COA, and imaging of the aorta and LV were conducted through Doppler echocardiography, cardiac catheterization, CT and MRI.
All 34 patients included in the study underwent percutaneous stent placement, according to the researchers.
They found that both Doppler and direct catheter assessments revealed a transcoarctation pressure gradient in all patients with mild COA, and these pressure gradients were significantly decreased by transcatheter intervention. A 75% decrease was seen in catheter peak-to-peak pressure gradient, and a 47.3% reduction was seen in Doppler echocardiography pressure gradient (P < .05).
However, these reductions had only a modest effect on aortic flow. Computed mean shear stress in the descending aorta was found to be reduced by 19.4%, and maximum time-averaged wall shear stress was reduced by 5.1% (P < .05), according to the findings. Additionally, the mean oscillatory shear index in the descending aorta was decreased by 13.3%, and the maximum oscillatory shear index was reduced by 10.1% (P < .05).
No patients achieved improvements in LV function, with a 4.48% decrease in stroke work, a 3.9% reduction in normalized stroke work and a 3.8% decrease in peak LV pressure (P < .05), the researchers wrote.
“Our findings suggest that the definition of ‘mild coarctation,’ based on [peak-to-peak transcoarctation pressure gradient] of 20 mm Hg, is an oversimplification and that more accurate assessments of this class of patients are required for deciding whether to perform a transcatheter intervention,” the researchers wrote. “Future studies must consider not only the upstream but also the downstream effects of coarctation repair when determining indication and assessing benefit of intervention.” – by Jennifer Byrne
Disclosure: The researchers report no relevant financial disclosures.
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