Department of Radiology Ehime University Graduate School of Medicine, Japan

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1 Detection of Left Atrial Appendage Thrombus by Cardiac Computed Tomography in Patients with Atrial Fibrillation and Initial Report about Feasibility of Scanning with Left Lateral Decubitus Position Department of Radiology Ehime University Graduate School of Medicine, Japan Naoki Fukuyama, Yuki Tanabe, Takahiro Yokoi, Teruhito Kido, Rami Yokoyama, Takuya Matsuda, Masashi Nakamura, Yoshiko Nishiyama, Masao Miyagawa, Teruhito Mochizuki

2 The author has no conflict of interest to disclose with respect to this presentation.

3 Introduction Transesophageal echocardiogram (TEE) is considered the gold standard modality in detecting left atrial appendage (LAA) thrombi in patients with atrial fibrillation (AF). However, this is a semi-invasive procedure. Cardiac computed tomography (CCT) has been proposed as an alternative method.

4 Introduction Although the patients with AF who underwent CCT (early phase) often have the filling defect area with LAA, adding delayed phase is an useful method to deny the existence of thrombi. early phase (CCT) delayed phase

5 Purpose The purpose of this study was to evaluate the diagnostic accuracy of CCT assessing LAA thrombi in comparison with TEE.

6 Methods We retrospectively reviewed 120 patients with AF who underwent CCT (early phase) with dorsal position using 256-slice multidetector row CT between January 2006 to November If there were filling defect of contrast medium in LAA, delayed scan would be additionally performed. Almost all patients underwent TEE within one day from CCT. <early phase (CCT)> retrospective-gating CM <delayed phase> prospective-gating CM

7 Characteristics n=120 Age (years) 61.7±10.5 Male : Female 86 (71.6 %) : 34 (28.4%) Paroxysmal AF : Persistent AF 90 (75%) : 30 (25%) Introduced anticoagulant therapy 113 (94.1 %) Presence or absence of AF during CT imaging 39 (32.5 %) Interval of CT and TEE (day) 0.73±1.22 Left ventricular ejection fraction (%) 61.1±11.3 Left ventricular ejection fraction 50% 17 (14.1 %)

8 Result 遅延相 <early phase (CCT)> TEE n=120 thrombus thrombus (+) (-) defect(+) 2 25 CT defect(-) 0 93 Sensitivity =100% Specificity = 92% Accuracy = 92.6% PPV=50% NPV=100% n=27 Sensitivity =100% Specificity = 92% Accuracy = 92.6% <delayed phase> thrombus (+) TEE thrombus (-) CT defect(+) 2 2 defect(-) 0 23 PPV=50% NPV=100% There were 25 false positive (FP) cases in early phase. By adding delayed scan, filling defects in LAA were confirmed not to be thrombi in 23 of 25 FP cases. However, there were still only 2 FP cases.

9 Previous reports <early phase (n=2955)> Sensitivity = 96% Specificity= 92% Accuracy = 94% PPV = 41% NPV = 99% <delayed phase (n=753)> Sensitivity =100% Specificity= 92% Accuracy = 99% PPV = 92% NPV =100% Romero J, et al. Circ Cardiovasc Imaging The literature about comparing the detectability of CCT and TEE reports the utility of delayed phase. However adding delayed phase improve PPV from 41% to 92%, FP cases are not completely eliminated. (Accuracy=99%)

10 False positive in delayed scan False Positive in delayed phase : our case delayed phase : defect (+) TEE : thrombi (-) In spite of adding the delayed phase, there were some FP cases. Those cases were required the evaluation with TEE. However, TEE is a semi-invasive procedure. So we formulate the method that is different from the conventional.

11 left lateral decubitus position We thought that CCT with left lateral decubitus position may improve diagnosis performance of thrombi because contrast medium filled in LAA effectively due to gravity. 8 patients with AF underwent experimentally CCT with left lateral decubitus position. dorsal position left lateral decubitus position

12 Case: 70 years old, Male < left lateral decubitus position > early phase (CCT) delayed phase TEE In both early phase and delayed phase, contrast medium filled in LAA. It was suspected of thrombi in LAA. This case was proved the thrombi by TEE.

13 Summary By adding delayed scan, filling defects in LAA were confirmed not to be thrombi in the FP cases. However, FP cases were not completely eliminated. CCT with left lateral decubitus position may improve PPV because contrast medium filled in LAA effectively.

14 Conclusion CCT would be a reliable alternative to TEE for the detection of LAA thrombi, particularly if delayed scan were performed. CCT with left lateral decubitus position may be more useful for detection of LAA thrombi.