Relation of left atrial appendage closure devices to topographic neighboring structures using standardized imaging by cardiac computed tomography angiography

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.

ST-Segment Elevation During Percutaneous Left Atrial Appendage Closure

A 70-year-old patient with paroxysmal atrial fibrillation underwent left atrial appendage closure. The patient experienced transient hypotension during device implantation. The procedure was abandoned because of ST-T-wave changes on electrocardiography and elevated coronary flow velocity on transesophageal echocardiography, which indicated that the device caused coronary artery compression.

Use of Computed Tomography for Left Atrial Appendage Occlusion Procedure Planning and Post-Procedure Assessment

Transcatheter left atrial appendage occlusion (LAAO) is an alternative to systemic anticoagulation in patients with non-valvular atrial fibrillation with increased risk for thromboembolic events. Pre- and post-procedural imaging is essential for technical success, allowing practitioners to identify contraindications, select appropriate devices, and recognize procedural complications. Although transesophageal echocardiography has traditionally served as the preeminent imaging modality in LAAO, cardiac computed tomography imaging has emerged as a noninvasive surrogate given its excellent isotropic spatial resolution, multiplanar reconstruction capability, rapid temporal resolution, and large field of view.

Incomplete neo-endothelialization of left atrial appendage closure devices is frequent after 6 months: a pilot imaging study

PURPOSE

To bridge neo-endothelialization (NE) of implanted left atrial appendage closure (LAA/LAAC) devices, dual antiplatelet therapy is prescribed. Cardiac computed tomography angiography (cCTA) has been proposed for the evaluation of interventional LAAC. This prospective longitudinal observational study applied a standardized imaging protocol to detect progression of NE of LAAC devices 6 months after implantation.

METHODS

Consecutive cCTA datasets of patients six months after LAAC were acquired and the standardized multi-planar reconstruction LAA occluder view for post-implantation evaluation (LOVE) algorithm was used. Residual flow of contrast agent inside the LAA without a peri-device leak (PDL) was defined as incomplete neo-endothelialization. Absence of residual flow was defined as complete neo-endothelialization. Since PDL allows residual flow in the LAA, irrespective of neoendothelialization, PDL were excluded from this study. Diabetes mellitus, liver disease, body-mass-index, age, device sizes and type will be assessed as predictors for incomplete NE.

RESULTS

53 consecutive patients were recruited for cCTA imaging. 36 (68%) showed no PDL and were included in the study (median age 77 years, 19% female). At median follow-up of 6 months (median 180 days, IQR 178-180), 44% of patients showed complete NE compared to 56% with NE still incomplete. Age, BMI, device type and size as well as prevalence of diabetes mellitus and liver disease did not show significant correlation with the completeness of NE.

CONCLUSION

This pilot study showed that neo-endothelialization is still incomplete in a majority of patients at mid-term follow-up of 6 months after successful LAAC therapy. Further investigation on the consequences of incomplete endothelialization is needed to guide antiplatelet therapy schedules.

Left atrial appendage occlusion device causing coronary obstruction: A word of caution

Closure of the left atrial appendage is a common procedure for patients with atrial fibrillation undergoing cardiac surgery. The technique of left atrial appendage occlusion (LAAO) by an extracardiac clip (AtriClip) is established as a reliable method. Acute coronary obstruction of the circumflex artery has already been described after minimally invasive LAAO. Here, we report a case of delayed circumflex artery obstruction after open-heart surgery. A patient who had mitral and tricuspid valve surgery in combination with AtriClip implantation suffered from myocardial infarction 24 h after clip implantation. Cardiac catheterization showed that the circumflex artery was obstructed on the level of the AtriClip device. The stenosis was treated by percutaneous coronary intervention with stent implantation. In conclusion, the surgeon should consider placing the AtriClip device slightly far away from the base of the left atrial appendage to avoid coronary obstruction.

Imaging risk features for device related pulmonary artery injury after left atrial appendage closure with Amplatzer™ Amulet™ device

OBJECTIVES

This study aimed to find imaging risk features for device related-pulmonary artery (PA) injury (DR-PAI) in patients after left atrial appendage closure (LAAC).

BACKGROUND

Cardiac tamponade resulting from DR-PAI is a rare but life-threatening complication of LAAC.

METHODS

In vitro analysis of Amplatzer™ Amulet™ (Abbott, MN) device was done. Measurements of the distance between PA and Amplatzer lobe at its middle part, distal part, and along the stabilizing wires' trajectory (wires-to-PA distance) were taken in 100 consecutive patients on post-LAAC computed tomography (CT) studies. Clinical outcomes were collected.

RESULTS

In vitro analysis indicated that both middle and distal lobe had to be in close PA proximity (<1.5 mm) for the stabilizing wires to cause risk for DR-PAI, configuration called ''cuddling lobe orientation''. On CT measurements middle lobe-PA distance was 4.7 mm (IQR = 2.7-9.5), with close proximity in 4 (4%) patients, and distal lobe-PA distance was 3.2 mm (IQR = 1.8-7.2 mm), with close proximity in 17 (17%) patients. Stabilizing wires were pointing toward PA in 47 patients (47%) with median wire-to-PA distance 5.7 mm (IQR = 3.6-8.5 mm). ''Cuddling'' was found in 2 (2%) patients and resulted in shorter wires-to-PA distance vs no ''cuddling'' group (2.3 vs 5.8 mm p <.01). At 2.9 ± 1.0 yrs of follow-up, the two patients with ''cuddling lobe orientation'' on post-LAAC CT scan developed late cardiac tamponades (p <.001). One of those required surgery, which confirmed DR-PAI.

CONCLUSIONS

''Cuddling lobe orientation'' of Amulet device with the PA was associated with short wires-to-PA distance and late pericardial effusions, including DR-PAI. Hence, such device-to-PA configuration should be avoided.

Systematic Review of Contiguous Vessel and Valve Injury Associated with Endocardial Left Atrial Appendage Occlusion Devices

Endocardial LAAO has been increasingly utilized in atrial fibrillation (AF) patients who are not suitable for long term oral anticoagulation. While overall procedural complications have decreased, rare complications like contiguous vessel and valve injury may be more frequently seen in the future with increase in the procedure volume. We performed a systematic search using predefined terms which reviewed all cases published in literature of contiguous vessel (pulmonary artery, pulmonary vein and left circumflex artery) and mitral valve injury caused by LAAO devices. Our results showed that Amplatzer Cardiac Plug (ACP) and Amplatzer Amulet devices were the most commonly used devices. Pulmonary artery perforation was the most commonly seen collateral vessel injury associated with LAAO. Close proximity of left atrial appendage to pulmonary artery was noted in all cases of pulmonary artery injury. Pulmonary artery injury commonly manifests as pericardial tamponade with hemodynamic collapse and is often fatal. Most common denominator of all the reviewed cases was the presence of an oversized LAAO device. In conclusion, collateral vessels and valve injury can be seen after LAAO mostly with double lobe devices such as ACP or Amulet. Increased awareness by the operators along with proper imaging and investigations could potentially mitigate such rare complications associated with LAAO.

Relation of left atrial appendage closure devices to topographic neighboring structures using standardized imaging by cardiac computed tomography angiography

Background

Although left atrial appendage (LAA) anatomy and topographic relations are well understood, little is known about the impairment of neighboring structures (NBS) by an implanted left atrial appendage closure (LAAC) device. This prospective longitudinal observational study for the first time describes distances of implanted LAA closure (LAAC) devices to NBS using a standardized imaging protocol of cardiac computed tomography angiography (cCTA).

Hypothesis

cCTA imaging is an eligible tool for post‐implantation evaluation of LAAC devices and their relation to neighboring structures.

Methods

cCTA data sets of consecutive patients 6 months after successful LAAC were acquired on a third generation dual‐source CT system and reconstructed with a slice thickness of 0.5 mm. The standardized multi‐planar reconstruction LAA occluder view for post‐implantation evaluation (LOVE) algorithm was used to measure the distances to NBS in relation to LAA morphology and implanted LAAC devices.

Results

A total of 48 patients (median age 80 years, 25% female) were included. Left upper pulmonary vein and circumflex artery were generally closest to occlusion devices (median 2.9 and 2.8 mm, respectively). AMPLATZER AMULET devices were closer to the mitral valve annulus than WATCHMAN devices (6.6 mm (inter quartile range [IQR] 4.9‐8.6) vs 10.9 mm (IQR 7.4‐14.0), P = 0.001). Distances to the left upper pulmonary vein were affected by LAA morphology, with cauliflower type having the closest proximity (1.7 mm [IQR 1.0‐3.4], P = 0.048).

Conclusion

A standardized cCTA imaging protocol is an eligible tool to accurately measure distances to NBS. Left upper pulmonary vein and circumflex artery are closest to LAAC devices and could thus be most prone to impairment.