Diagnostic accuracy of bicuspid aortic valve by echocardiography

Background: Echocardiography is regarded as the gold standard for diagnosis of bicuspid aortic valve (BAV), yet diagnostic accuracy has been evaluated previously only in single-center studies. We systematically evaluated the accuracy of BAV diagnosis in a large healthcare system of multiple echocardiography laboratories. Methods and Results: Aurora Health Care is a multihospital, multi-clinic system across the state of Wisconsin encompassing 33 inpatient and outpatient echocardiography laboratories with 39 cardiologist readers and 72 sonographers. As all laboratories store echocardiograms in one database, we queried all patients with "bicuspid aortic valve" diagnosis on echocardiography. Echocardiograms were classified as "BAV" or "possible BAV" based on initial reader confidence. An expert review panel categorized each as BAV, no BAV, or Indeterminate. Of the 745 cases identified, 589 (79.1%, initial reader interpretation: n = 494 "BAV," n = 95 "possible") were BAV. A high level of agreement (84%) was present in BAV diagnosis. There were 156 (20.9%) echocardiograms that were no BAV (8.4%) or Indeterminate (12.4%). We identified three common reasons for misdiagnosis: poor image quality (n = 70, 44.9%), leaflet calcium (n = 44, 28.2%), and oblique axis imaging (n = 33, 21.1%). A clear reason for misclassification was not elucidated in nine cases (n = 9, 5.7%). Conclusions: This is the first study to evaluate BAV accuracy across a community health system with multiple echocardiography laboratories and a heterogeneous group of readers and sonographers. We establish a high degree of accuracy of echo-cardiography in BAV diagnosis and draw attention to common echocardiographic pitfalls that lead to BAV misclassification, highlighting opportunities for education and quality improvement.