Prone‐position computed tomography in the late phase for detecting intracardiac thrombi in the left atrial appendage before catheter ablation for atrial fibrillation

Figure 1. Difference in the contrast defects (CDs) on computed tomography between the early and late phases A CD (arrow) was seen on top of the left atrial appendage in the early phase (A), which was replaced with contrast medium in the late phase (D, arrowhead)

Figure 2. Change in contrast defects (CDs) by altered oral anticoagulant therapy. Contrast computed tomography (CT) in the prone position was performed in the early (A) and late phases (B). Both images showed CDs. We changed the oral anticoagulant from edoxaban to rivaroxaban, and 3 months later, subsequent CT showed the disappearance of the CD, and residual contrast was observed along the margin of the left atrial appendage under the same CT conditions (C). Arrows show CDs, and arrowheads show residual contrast

Figure 3. Contrast defect (CD) after left atrial appendage (LAA) closure The patients had undergone clipping of LAA during coronary artery bypass graft surgery. There remained an LAA portion between the site of the LAA clipping and entrance of the LAA after the surgery. CDs were observed with contrast computed tomography (CT) in both the early (A) and late phases (B) at the left atrial side of the LAA closure. The anticoagulant was switched from rivaroxaban to dabigatran, and 38 days later, the subsequent late‐phase prone‐position contrast CT (late‐pCT) showed a much larger CD in the same area as the LAA (C). Then, we changed the agent to warfarin, and finally, the CD vanished on late‐pCT 58 days after second CT scanning (D). Arrows show CDs

Figure 4. Contrast defect (CD) changes in association with the CT position and scanning phase. This patient was administered apixaban for more than 3 months for persistent atrial fibrillation. Contrast computed tomography (CT) in the supine position was performed, and a CD was detected in both the early and late phases (A) and (B). The patient was intolerant to transesophageal echocardiogram due to difficulties in swallowing the echo probe. A week from CT performed in the supine position, CT in the prone position was performed under the same anticoagulant type and dose conditions. A CD was only detected using CT in the early phase (C), but not in the late phase (D). Arrows show CDs, and arrowheads show residual contrast

Figure 5. Receiver operating characteristic curve analysis of the left atrial appendage (LAA) blood velocity depending on the presence of residual contrast medium in the LAA. The cutoff value of residual contrast medium in the LAA during late‐phase contrast computed tomography in the prone position was 15.0 cm/s. The sensitivity and specificity were 0.900 and 0.621, respectively. AUC, area under the curve