Usefulness of Dual-Phase Snapshot 320-Detector Computed Tomography for the Detection of a Left Atrial Appendage Thrombus

The diagnostic performance of 320-detector cardiac computed tomography (CCT) for the detection of thrombi in the left atrial appendage (LAA), relative to transesophageal echocardiography (TEE) as the gold standard, has not yet been evaluated. A total of 91 consecutive patients who were scheduled to undergo pulmonary vein isolation and underwent TEE and CCT were enrolled in this study. Delayed scanning on CCT was performed following early scanning, at 60 seconds after the start of the contrast injection. The radiation dose was estimated for both scans. The early scans showed a contrast medium filling defect (FD) in the LAA in 27 patients, whereas the delayed scans showed an FD in the LAA in six patients. Of these, five patients were confirmed to have a thrombus in the LAA by TEE. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 100, 74.4, 18.5, 100, and 75.8% for early scanning and 100, 98.8, 83.3, 100, and 98.9% for delayed scanning, respectively. The area under the curve for the detection of a thrombus in the LAA on the delayed scans was significantly larger than that for the detection on the early scans (0.99 versus 0.87, P < 0.001). The estimated median radiation doses for the early and delayed scans were 2.86 and 0.42 mSv, respectively. Addition of delayed scanning to early scanning improved the diagnostic performance for the detection of a thrombus in the LAA and may obviate unnecessary TEE, with minimal additional radiation exposure.