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Cardiac Magnetic Resonance Imaging Is More Diagnostic Than 2-Dimensional Echocardiography in Determining the Presence of Bicuspid Aortic Valve
Study Questions:
Is cardiac magnetic resonance imaging (CMRI) more accurate than transthoracic echocardiography (TTE) to identify bicuspid aortic valves?
Methods:
This retrospective study examined 218 individuals who had both TTE and CMRI prior to aortic valve surgery, and compared the accuracy of these techniques to identify a bicuspid aortic valve using surgical inspection as a reference standard. This study examined a population of individuals in which 56% had bicuspid aortic valves by surgical inspection.
Results:
For assessment of aortic valve morphology, TTE was graded as diagnostic in 71% of individuals, whereas CMRI was graded as diagnostic in 97% of patients (p < 0.001). When limited to studies graded as diagnostic by the readers, the sensitivity was 86% and 96% for TTE and CMRI, respectively; and the specificity was 96% for both modalities. Of the 123 patients with bicuspid aortic valve confirmed at surgery, TTE correctly identified 62% preoperatively as having a bicuspid aortic valve, 10% were misidentified with a trileaflet aortic valve, and 28% were nondiagnostic for valve morphology using TTE. In this same cohort, CMRI correctly identified 93% with bicuspid aortic valve, 4% were misidentified with a trileaflet aortic valve, and 2% were nondiagnostic. The difference between TTE and CMRI to determine the presence of a bicuspid aortic valve was statistically significant (p < 0.001).
Conclusions:
CMRI is more likely to adequately visualize aortic valve morphology amongst individuals undergoing aortic valve surgery. Amongst studies graded as diagnostic, CMRI has a higher sensitivity to identify a bicuspid aortic valve. CMRI may be a useful test to characterize aortic valve morphology in combination with TTE.
Perspective:
Accurate identification of bicuspid aortic valves is important for surgical planning, presurgical management, ascertainment of individuals at risk of other abnormalities such as aortic aneurysms, and for potential consideration of alternative procedures such as transcatheter aortic valve implantation. This study demonstrates that TTE frequently cannot adequately visualize aortic valve morphology. Further, even in TTE studies graded as diagnostic, TTE misclassifies a number of bicuspid aortic valves. In comparison, CMRI has substantially higher rates of diagnostic image quality, and has somewhat higher sensitivity to detect bicuspid aortic valves. Based on the study findings, CMRI may be a reasonable method to characterize aortic valve morphology when TTE studies are nondiagnostic, other testing such as transesophageal echocardiography are not planned, or when highly accurate characterization of the aortic valve is clinically important.
Keywords: Heart Defects, Congenital, Heart Valve Diseases, Magnetic Resonance Imaging, Echocardiography, Transesophageal
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