Author + information
- Kazuhiro Osawa,
- Rine Nakanishi,
- Dong Li,
- Eranthi Jayawardena,
- Nicholas Kim,
- Sina Rahmani,
- Negin Nezarat,
- Hong Qi and
- Matthew Budoff
Background: Atrial fibrillation (AF) increases the risk of thromboembolic events by promoting thrombus formation in the left atrial appendage (LAA). Delayed enhancement by cardiac computed tomography angiography (CCTA) is a reliable method in evaluating LAA thrombus. Previously, studies using CCTA have demonstrated an optimal value of LAA Hounsfield unit (HU) and the ratio of LAA/ascending aorta (AA) HU and showed an excellent diagnostic accuracy for detecting LAA thrombus compared to TEE as a reference standard. The purpose of this study was to determine the optimal cutoff value of LAA HU and the ratio of LAA/AA HU in detecting LAA thrombus compared with delayed enhancement by CCTA as a reference standard.
Methods: In this study, 102 AF participants treated with warfarin who underwent CCTA were enrolled. All CT examination was performed with delayed enhancement. LAA thrombus was evaluated visually using delayed enhancement images. In the initial scanning images, the value of LAA HU and the ratio of LAA/AA HU was measured in a 1 cm area of interest in the LAA and AA in the same axial plane.
Results: Of the 102 patients (65 male, mean age 60±11 years old), 11 (11%) had LAA thrombus. The LAA HU in the initial scanning was significantly lower in patients with LAA thrombus than without LAA thrombus (65±15 HU vs.256±90HU, p<0.01). The receiver operating characteristics curve (ROC) analysis of the LAA HU in the initial scanning showed an optimal cutoff value of 91.6 for identification of LAA thrombus, with sensitivity of 100%, specificity of 95.6%, and area under the curve (AUC) of 0.976 (95% CI 0.924, 0.996, P <0.001). Moreover, the ROC analysis of the ratio of LAA/LA HU in the initial scanning showed an optimal cutoff value of 0.240 for identification of LAA thrombus, with sensitivity of 100%, specificity of 91.2%, and AUC of 0.969 (95% CI 0.914,0.993, P <0.001 at Area=0.5).
Conclusions: The CT value of 91.6 HU in LAA and the ratio of LAA/AA HU (0.240) in the initial scanning can predict LAA thrombus detected by delayed enhancement as a reference standard. Thus, evaluating the CT value in LAA and the ratio of LAA/AA HU by initial scanning could be of value when assessing the risk of thromboembolic in AF patients.
Poster Hall, Hall C
Friday, March 17, 2017, 3:45 p.m.-4:30 p.m.
Session Title: Non Invasive Imaging: Expanding Clinical Applications
Abstract Category: 27. Non Invasive Imaging: CT/Multimodality, Angiography, and Non-CT Angiography
Presentation Number: 1161-227
- 2017 American College of Cardiology Foundation