Cardiac CT angiography after percutaneous left atrial appendage closure: early versus delayed scanning after contrast administration

Position Statement on Cardiac Computed Tomography Following Left Atrial Appendage Occlusion

Left atrial appendage occlusion (LAAO) is rapidly growing as valid stroke prevention therapy in atrial fibrillation. Cardiac imaging plays an instrumental role in preprocedural planning, procedural execution, and postprocedural follow-up. Recently, cardiac computed tomography (CCT) has made significant advancements, resulting in increasing use both preprocedurally and in outpatient follow-up. It provides a noninvasive, high-resolution alternative to the current standard, transesophageal echocardiography, and may display advantages in both the detection and characterization of device-specific complications, such as peridevice leak and device-related thrombosis. The implementation of CCT in the follow-up after LAAO has identified new findings such as hypoattenuated thickening on the atrial device surface and left atrial appendage contrast patency, which are not readily assessable on transesophageal echocardiography. Currently, there is a lack of standardization for acquisition and interpretation of images and consensus on definitions of essential findings on CCT in the postprocedural phase. This paper intends to provide a practical and standardized approach to both acquisition and interpretation of CCT after LAAO based on a comprehensive review of the literature and expert consensus among European and North American interventional and imaging specialists.

A preliminary study of minimal left atrial appendage occlusion using Watchman under the guidance of fluoroscopy

BACKGROUND

Left atrial appendage occlusion (LAAO) has been considered an alternative treatment to prevent embolic stroke in patients with nonvalvular atrial fibrillation (NVAF). However, it carries a risk of general anesthesia or esophageal injury if guided by transesophageal echocardiography (TEE).

AIMS

We aimed to investigate the feasibility and safety of minimal LAAO (MLAAO) using Watchman under fluoroscopy guidance alone in patients with NVAF.

METHODS

A total of 249 consecutive patients with NVAF who underwent LAAO using the WATCHMAN device were divided into two groups: the Standard LAAO (SLAAO) group and the MLAAO group. Procedural characteristics and follow-up results were compared between the two groups.

RESULTS

There was no statistically significant difference in the rate of successful device implantation (p > 0.05). Fluoroscopy time, radiation exposure dose, and contrast medium usage in the MLAAO group were higher than those in the SLAAO group (p < 0.001). The procedure time and hospitalization duration were significantly lower in the MLAAO group than those in the SLAAO group (p < 0.001). The occluder compression ratio, measured with fluoroscopy, was lower than that measured with TEE (17.63 ± 3.75% vs. 21.69 ± 4.26%, p < 0.001). Significant differences were observed between the SLAAO group and the MLAAO group (p < 0.05) in terms of oropharyngeal/esophageal injury, hypotension, and dysphagia. At 3 months after LAAO, the MLAAO group had a higher incidence of residual flow within 1-5 mm compared to the SLAAO group, although the difference was not statistically significant.

CONCLUSION

MLAAO guided by fluoroscopy, instead of TEE, without general anesthesia simplifies the operational process and may be considered safe, effective, and feasible, especially for individuals who are unable to tolerate or unwilling to undergo TEE or general anesthesia.

The effect of two different methods of planning landing zone for left atrial appendage closure by cardiac computed tomography angiography: a comparative study

Background

To explore the value of 2 different methods for planning landing zone for left atrial appendage closure (LAAC) by cardiac computed tomography angiography (CCTA).

Methods

A retrospective analysis was performed on the clinical data of patients who successfully underwent LAAC with the Watchman device at The Affiliated Taizhou People's Hospital of Nanjing Medical University from August 2020 to February 2022. Two different methods were used to plan the landing zone and measure the longest diameter, average diameter, depth, and perimeter of the landing zone. The difference between the 2 methods and the correlation between their measurements and occluder size were analyzed.

Results

A total of 66 patients undergoing LAAC were included, with an average age of 69.35±7.1 years, of whom 30 (45.5%) were women. The mean error between the longest diameter measured by the traditional method and the actual value was 2.90±2.83 mm, and the mean absolute error (MAE) was 2.71 (1.17, 4.38) mm. The mean error between the longest diameter measured by the new method and the actual value was 0.9 (-0.13, 2.50) mm, and its MAE was 1.4 (0.40, 2.53) mm. The error of the longest diameter measured by the traditional method was larger than that measured by the new method (P<0.001). The mean error between the depth measured by the traditional method and the actual value was 1.40±3.45 mm, and the MAE was 2.36 (0.74, 4.58) mm. The mean error between the depth measured by the new method and the actual value was 0.10 (-1.33, 1.95) mm, and the MAE was 1.55 (0.60, 3.10) mm. Likewise, the depth error measured by the traditional method was larger than that measured by the new method (P<0.05). The correlation between the perimeter and the size of the occluder was the strongest (r=0.919, P<0.001).

Conclusions

With CCTA, the new method is more accurate in planning landing zone than the traditional method. It is particularly important to select the occluder size for the patients with flat oval landing zone ostium.

Comparison of different quantitative evaluation protocols for peri-device leak detection using cardiac computed tomography angiography after left atrial appendage closure

This study seeks to propose and compare different quantitative evaluation methods for identifying patients with peri-device leak (PDL) using cardiac computed tomography angiography (CCTA). Patients who had undergone left atrial appendage (LAA) closure and both transesophageal echocardiography (TEE) and CCTA were enrolled. Hounsfield units (HU) were measured in the proximal and distal regions of the left atrial appendage (p-LAA, d-LAA) on the CCTA, and the average of the two was determined (a-LAA). The relative HU ratios of the LAA to the center of the left atrium (LA) were calculated (p-LAA/c-LA, d-LAA/c-LA, a-LAA/c-LA). The area under the curve (AUC) for the LAA HU and the LAA/LA HU ratio were analyzed and compared. Fifty-one patients were included in this study. Pairwise comparisons showed a statistically significant difference (p = 0.029) in diagnostic performance between the d-LAA (AUC = 0.868) and a-LAA (AUC = 0.972). There were no significant differences between the a-LAA and p-LAA (p = 0.549) or between the d-LAA and p-LAA (p = 0.053). At the optimal cutoff for a-LAA of 115.5 HU, the sensitivity was 100%, the specificity was 88%. At the optimal cutoff for p-LAA of 109 HU, the sensitivity was 100%, the specificity was 84%. The LAA/LA HU ratio did not exhibit better diagnostic performance than HU attenuation in the LAA (p > 0.05). The a-LAA > 115.5 is useful in identifying PDL. Due to its convenience and intuitiveness, p-LAA > 109.0 can also be used as an alternative protocol for a-LAA.