Background: Left atrial appendage (LAA) occlusion using the Amplatzer Cardiac Plug (ACP) aims to reduce the risk of stroke in patients with atrial fibrillation. The ACP comprises a lobe positioned at landing zone (LZ) 1cm deep of the ostium, and a disc placed across the ostium. Initial sizing recommendations of the ACP were 1.5-3mm larger than the measured LZ. With increasing experience a more aggressive upsizing protocol (3-8mm) was adopted. We aimed to assess the impact of device size on post implantation LAA size and geometry.
Methods: Offline measurements were performed on intraprocedural TEE images of 63 patients undergoing LAA occlusion with ACP. Using three principal angulations (0,45 and 90°) measures were performed on the LAA LZ and ostium prior to device deployment and of the insitu lobe (stretched LZ) and disc post deployment.
Results: The selected lobe size was 5.8+2.6mm p+2.6mm p° and 90° respectively. This resulted in a stretched increase in the LZ of 4.8+3.1 p+3.3 p° and 90° respectively. The eccentricity index was the same for both LZ and ostium (1.05+0.04 p=0.598). Strong correlations (Spearman R 0.8-0.9) were found between device size and post-implantation measurements. The selected disc size was larger than intra-procedure ostium by 5.8+5.8 mm, 6.9+4.1 mm and 7.4+4.0 mm for angulations of 0°,45° and 90° respectively. Shortening of the deployed disc due to convexity was found in a single plane only with the convexity index calculated at 6%[(1.9 (-0.1 - 3.3 mm) p=0.039], 3% [(0.7 (-0.6 - 2.5 mm) p=0.006] and 0.6% [(0.5 (-1.4 - 2.4 mm) p=0.546] for the 3 views.
Conclusions: The LAA landing zone appears to accommodate well to significant device upsizing. The difference between intra-procedure and post-implantation measurements remained constant regardless of oversizing. Interestingly disc shortening due to convexity appears to be limited to a single plane.
