Pre- and Postprocedural CT of Transcatheter Left Atrial Appendage Closure Devices

Utility of CT and MRI in Cardiac Electrophysiology

Cardiac electrophysiology involves the diagnosis and management of arrhythmias. CT and MRI play an increasingly important role in cardiac electrophysiology, primarily in preprocedural planning of ablation procedures but also in procedural guidance and postprocedural follow-up. The most common applications include ablation for atrial fibrillation (AF), ablation for ventricular tachycardia (VT), and for planning cardiac resynchronization therapy (CRT). For AF ablation, preprocedural evaluation includes anatomic evaluation and planning using CT or MRI as well as evaluation for left atrial fibrosis using MRI, a marker of poor outcomes following ablation. Procedural guidance during AF ablation is achieved by fusing anatomic data from CT or MRI with electroanatomic mapping to guide the procedure. Postprocedural imaging with CT following AF ablation is commonly used to evaluate for complications such as pulmonary vein stenosis and atrioesophageal fistula. For VT ablation, both MRI and CT are used to identify scar, representing the arrhythmogenic substrate targeted for ablation, and to plan the optimal approach for ablation. CT or MR images may be fused with electroanatomic maps for intraprocedural guidance during VT ablation and may also be used to assess for complications following ablation. Finally, functional information from MRI may be used to identify patients who may benefit from CRT, and cardiac vein mapping with CT or MRI may assist in planning access. ©RSNA, 2024 Supplemental material is available for this article.

CAR and CSTR Cardiac Computed Tomography (CT) Practice Guidelines: Part 2-Non-Coronary Imaging

The cardiac computed tomography (CT) practice guidelines provide an updated review of the technological improvements since the publication of the first Canadian Association of Radiologists (CAR) cardiac CT practice guidelines in 2009. An overview of the current evidence supporting the use of cardiac CT in the most common clinical scenarios, standards of practice to optimize patient preparation and safety as well as image quality are described. Coronary CT angiography (CCTA) is the focus of Part I. In Part II, an overview of cardiac CT for non-coronary indications that include valvular and pericardial imaging, tumour and mass evaluation, pulmonary vein imaging, and imaging of congenital heart disease for diagnosis and treatment monitoring are discussed. The guidelines are intended to be relevant for community hospitals and large academic centres with established cardiac CT imaging programs.

A Comprehensive Review of Percutaneous and Surgical Left Atrial Appendage Occlusion

Atrial fibrillation (AF) is the most common arrhythmia worldwide, and is associated with a significant risk of thromboembolic events. Left atrial appendage occlusion (LAAO) has emerged as a promising alternative for patients with contraindications or intolerance to anticoagulant therapy. This review summarises the current evidence, indications, and technical advancements in surgical and percutaneous LAAO. Preprocedural planning relies on various imaging techniques, each with unique advantages and limitations. The existing randomised clinical trials and meta-analyses demonstrate favourable results for both percutaneous and surgical LAAO. Postprocedural management emphasises personalised anticoagulation strategies and comprehensive imaging surveillance to ensure device stability and detect complications. Future focus should be put on antithrombotic regimens, investigating predictors of device-related complications, and simplifying procedural aspects to enhance patient outcomes. In summary, LAAO is presented as a valuable therapeutic option for preventing AF-related thromboembolic events, with ongoing research aimed at refining techniques and improving patient care.

Cardiothoracic Medical Devices - A Pictorial Review

The rapid advancement of medical technology has introduced a plethora of innovative devices designed for use within the thoracic cavity. Familiarity with the characteristic imaging features of these devices, their purpose and desired positioning is crucial for radiologists to identify them promptly and accurately assess any associated complications. This pictorial review provides a comprehensive overview of the radiologic findings associated with various new chest devices, aiming to equip radiologists with the knowledge required for effective clinical management.

A Comparative Study of Thoracoscopic Left Atrial Appendage Clipping vs Stapled Resection

BACKGROUND

The left atrial appendage (LAA) is the predominant site of thrombus formation in atrial fibrillation (AF), which is associated with ischemic stroke. This study comparatively evaluated the complete LAA closure rates between LAA clipping and stapled resections.

METHODS

The study included 333 patients who underwent thoracoscopic operation with both preoperative and postoperative computed tomographic scans. Propensity score matching (4:1 ratio) was applied, matching 90 LAA clipping patients with 206 stapled resection patients. The primary end point was complete LAA closure, defined as a residual LAA depth of <1 cm on computed tomographic images obtained 1 year postoperatively.

RESULTS

No 30-day death was observed. Complete LAA closure was achieved in 85.9% (286 of 333) of patients. After propensity score matching, the clipping group demonstrated a significantly higher complete LAA closure rate than the stapled resection group (95.6% vs 83.0%, P = .003). The residual LAA stump depth was also shorter in the clipping group compared with the stapled resection group (2.9 vs 5.3 mm, P = .001). Two patients with a residual LAA stump exhibited an association with ischemic stroke during follow-up.

CONCLUSIONS

The clipping group demonstrated a higher rate of complete LAA closure compared with the stapled resection group. Close monitoring of patients with residual LAA stumps is essential. Further research with larger cohorts is needed to elucidate impact of the residual LAA stump on thromboembolic events.

ACR Appropriateness Criteria® Preprocedural Planning for Left Atrial Procedures in Atrial Fibrillation

This document summarizes the relevant literature for the selection of preprocedural imaging in three clinical scenarios in patients needing endovascular treatment or cardioversion of atrial fibrillation. These clinical scenarios include preprocedural imaging prior to radiofrequency ablation; prior to left atrial appendage occlusion; and prior to cardioversion. The appropriateness of imaging modalities as they apply to each clinical scenario is rated as usually appropriate, may be appropriate, and usually not appropriate to assist the selection of the most appropriate imaging modality in the corresponding clinical scenarios. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Role of Computed Tomography in Cardiac Electrophysiology

With the increasing prevalence of arrhythmias, the use of electrophysiology (EP) procedures has increased. Recent advancements in computed tomography (CT) technology have expanded its use in pre-assessments and post-assessments of EP procedures. CT provides high-resolution images, is noninvasive, and is widely available. This article highlights the strengths and weaknesses of cardiac CT in EP.

Validation study of new left atrial appendage closure device measurement by two-dimensional and three-dimensional transesophageal echocardiography

BACKGROUND

In left atrial appendage closure using WATCHMAN FLX, accurate device measurement by transesophageal echocardiography (TEE) is important. We aimed to experimentally validate appropriate methods of device measurement with two-dimensional (2D) and three-dimensional (3D) TEE compared with actual size.

METHODS

We prepared a full range of device sizes (20, 24, 27, 31, 35 mm), each with five different compression rates. Each device was measured by 2D and 3D TEE at depths of 2, 4, and 6 cm in vitro using inner, outer, and middle line methods. We compared the difference between the actual size by caliper and measurements at each compression rate and depth by the three methods in 2D and 3D TEE.

RESULTS

A total of 450 patterns of measurements were analyzed. The differences using the middle line method were much less than those using the inner and outer line methods in 2D and 3D TEE (2D TEE: 0.45 ± 0.36 vs. 2.55 ± 0.99 vs. 2.59 ± 0.72 mm, p < 0.01; 3D TEE: 0.34 ± 0.27 vs. 2.38 ± 0.69 vs. 1.86 ± 0.77 mm, p < 0.01). Moreover, the differences in measurements by 3D TEE were more accurate than those of 2D TEE in the inner (2.47 ± 1.86 vs. 1.86 ± 0.77 mm, p < 0.01) and middle (0.58 ± 0.37 vs. 0.34 ± 0.27 mm, p < 0.01) line methods.

CONCLUSIONS

Middle line method by 3D TEE is the most reliable approach for device measurement at left atrial appendage closure using WATCHMAN FLX device.

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.

Midterm follow-up after computed tomography angiography planned left atrial appendage closure

BACKGROUND

While studies have shown the advantages of computed tomography angiography (CTA) over transesophageal echocardiography (TEE) in left atrial appendage closure (LAAC) preprocedural planning for WATCHMAN™ legacy and FLX devices, there has been no reported long-term data for this approach.

OBJECTIVES

We sought to evaluate long-term outcomes using CTA-based preprocedural planning for LAAC using the WATCHMAN™ device.

METHODS

A prospective analysis of 231 consecutive patients who underwent LAAC in a single, large academic hospital in the United States was conducted over a 5-year period. CTA-guided preprocedural planning was performed in all. Procedural success, adverse events, length of procedure, number of devices used, and length of stay were evaluated. Rates of death, cerebral embolism, systemic embolism, and major and minor bleeding were recorded. Adjusted predicted stroke and major bleeding rates were derived from CHA2DS2-Vasc and HAS-BLED scores, respectively.

RESULTS

From January 26, 2017, to November 23, 2021, 231 patients underwent LAAC with CTA preprocedural planning by two operating physicians. The mean age of patients was 76.5 ± 8.4. 59.7% of patients were male. Mean CHA2DS2VASc and HAS-BLED scores were 4.5 ± 1.4 and 3.9 ± 0.9, respectively. All procedures were performed with intracardiac echo (100%). The procedural success rate was 99.1%. The CTA sizing strategy accurately predicted the implant size in 93.5% of patients. Mean number of devices used was 1.10 ± 0.3. Peri-procedural complication rate was 2.2%. 6 patients were lost to follow-up. Mean follow-up was 608.94 days with a total of 377.04 patient years. Median follow-up period of 368 days (interquartile range: 209-1067 days). There were 51 deaths from all causes (13.52 per 100 patient-years), 10 cases of cerebral embolism (2.65 per 100 patient-years), 2 cases of systemic embolism (0.53 per 100 patient-years), 17 cases of major bleeding (4.50 per 100 patient-years), and 31 cases of minor bleeding (8.2 per 100 patient-years). All-cause mortality at 1, 2, and 3 years was 12.7%, 20.9%, and 29.2%, respectively. CV event rates at 1, 2, and 3 years were 2.1%, 6.6%, and 10.5%, respectively.

CONCLUSIONS

CTA-based preprocedural planning is accurate in predicting device size for LAAC and associated with excellent clinical outcomes at 5 years.

Device-Related Thrombus After Left Atrial Appendage Occlusion: Clinical Impact, Predictors, Classification, and Management

Despite the unprecedented advances in the left atrial appendage occlusion field, device-related thrombus (DRT) remains an unresolved issue with the therapy. This paper aims to provide a state-of-the-art review of the literature on the incidence, clinical impact, predictors and management of DRT and propose a novel classification of DRT and hypoattenuated thickening.

The Left Atrial Appendage and Atrial Fibrillation-A Contemporary Review

In patients with atrial fibrillation, the left atrial appendage may serve as the site of thrombus formation due to stasis that occurs within the appendage because of its shape and trabeculations. Although thrombus formation can be reduced by using anticoagulants, this may be contraindicated in some patients. The need for a better alternative treatment prompted the study of left atrial appendage occlusion for thromboembolism prophylaxis. Due to this, procedures that excise or occlude the left atrial appendage have gained attention because of their ability to prevent thromboembolic events. This article provides a comprehensive review of the left atrial appendage and its associated procedures' clinical utility.

The CT derived angle between the transseptal puncture site and the left atrial appendage as a predictor for complex interventional occlusion procedures

OBJECTIVE

To evaluate the role of the CT-derived angle between the intra-atrial septum (IAS) and the left atrial appendage (LAA) on procedural complexity and clinical outcomes in left atrial appendage occlusion (LAAO) procedures.

BACKGROUND

Given the broad variations in anatomy, LAAO remains one of the most challenging interventional procedures in structural heart disease. In recent years, preprocedural cardiac tomography (CT) has evolved as a valuable tool; however, prediction of procedural complexity remains cumbersome.

METHODS

We retrospectively analyzed 47 patients that underwent LAAO at our center in whom pre-procedural cardiac CT-scans were available. Among other baseline parameters, we measured the angle between the LAA ostium and the preferred transseptal puncture site at the IAS. We compared patients with an angle above and below the median regarding procedural characteristics and procedural outcome.

RESULTS

The median angle between the LAA and the IAS was 127.3° (IQR: 120.9-141.3). LAAO took longer in patients with a measured angle below the median (55.0 ± 22.7 min vs. 41.3 ± 17.5 min; p = .04), resulting in longer radiation times (13.0 ± 5.3 min vs. 9.8 ± 5.7 min; p = .04) and more contrast use (61.1 ± 47.5 mL vs. 33.6 ± 24.7 mL; p = .05). Moreover, the necessity for a sheath exchange was significantly higher (30.4% vs. 4.2%, p = .02) and device repositioning or device resizing trended to be more frequent (26.1% vs. 8.3%; p = .1 and 21.7% vs. 8.3%; p = .2). There were no differences in procedural outcome, device-position and peri-device leak (PDL).

CONCLUSIONS

The angle between the transseptal puncture site and the LAA ostium may serve as a predictor for more demanding LAAO interventions. In our study a steeper angle led to a prolonged procedure resulting in higher doses of contrast and radiation, but was not associated with a worse procedural outcome.

Cardiac magnetic resonance imaging for preprocedural planning of percutaneous left atrial appendage closure

Introduction

Percutaneous closure of the left atrial appendage (LAA) facilitates stroke prevention in patients with atrial fibrillation. Optimal device selection and positioning are often challenging due to highly variable LAA shape and dimension and thus require accurate assessment of the respective anatomy. Transesophageal echocardiography (TEE) and x-ray fluoroscopy (XR) represent the gold standard imaging techniques. However, device underestimation has frequently been observed. Assessment based on 3-dimensional computer tomography (CTA) has been reported as more accurate but increases radiation and contrast agent burden. In this study, the use of non-contrast-enhanced cardiac magnetic resonance imaging (CMR) to support preprocedural planning for LAA closure (LAAc) was investigated.

Methods

CMR was performed in thirteen patients prior to LAAc. Based on the 3-dimensional CMR image data, the dimensions of the LAA were quantified and optimal C-arm angulations were determined and compared to periprocedural data. Quantitative figures used for evaluation of the technique comprised the maximum diameter, the diameter derived from perimeter and the area of the landing zone of the LAA.

Results

Perimeter- and area-based diameters derived from preprocedural CMR showed excellent congruency compared to those measured periprocedurally by XR, whereas the respective maximum diameter resulted in significant overestimation (p < 0.05). Compared to TEE assessment, CMR-derived diameters resulted in significantly larger dimensions (p < 0.05). The deviation of the maximum diameter to the diameters measured by XR and TEE correlated well with the ovality of the LAA. C-arm angulations used during the procedures were in agreement with those determined by CMR in case of circular LAA.

Discussion

This small pilot study demonstrates the potential of non-contrast-enhanced CMR to support preprocedural planning of LAAc. Diameter measurements based on LAA area and perimeter correlated well with the actual device selection parameters. CMR-derived determination of landing zones facilitated accurate C-arm angulation for optimal device positioning.

Impact of Preprocedure Imaging for Left Atrial Appendage Occlusion: Insights From the NCDR LAAO Registry

BACKGROUND

The impact of preprocedure imaging on the safety and effectiveness of left atrial appendage occlusion (LAAO) remains unclear.

OBJECTIVES

This study sought to determine the rates of use of preprocedure computed tomography (CT)/cardiac magnetic resonance (CMR) and its association with safety and effectiveness of LAAO procedures.

METHODS

The National Cardiovascular Data Registry LAAO Registry was used to evaluate patients who underwent attempted LAAO with the WATCHMAN and WATCHMAN FLX devices between January 1, 2016, and June 30, 2021. Safety and effectiveness of LAAO procedures was compared by use vs nonuse of preprocedural CT/CMR. Outcomes of interest included implantation success (deployment and release of device), device success (device released with peridevice leak <5 mm), and procedure success (device released with peridevice leak <5 mm and no in-hospital major adverse events [MAE]). Multivariable logistic regression was used to assess the relationship between preprocedure imaging and outcomes.

RESULTS

Preprocedure CT/CMR was used for 18.2% (n = 20,851) of the 114,384 procedures in this study. CT/CMR use was more common among government and university hospitals and hospitals in the Midwest and South; it was less common among patients with uncontrolled hypertension, with abnormal renal function, and without prior thromboembolism. Overall rates of implantation success, device success, and procedure success were 93.4%, 91.2%, and 89.4%, respectively. Preprocedure CT/CMR was independently associated with an increased likelihood of implantation success (OR: 1.08; 95% CI: 1.00-1.17), device success (OR: 1.10; 95% CI: 1.04-1.16), and procedural success (OR: 1.07; 95% CI: 1.02-1.13). MAE were uncommon (2.3%) and not associated with use of preprocedure CT/CMR (OR: 1.02; 95% CI: 0.92-1.12).

CONCLUSIONS

Preprocedure CT/CMR was associated with an increased likelihood of successful LAAO implantation; however, the magnitude of benefit appears small and it was not associated with MAE.

State of the art paper: Cardiac computed tomography of the left atrium in atrial fibrillation

The clinical spectrum of atrial fibrillation means that a patient-individualized approach is required to ensure optimal treatment. Cardiac computed tomography can accurately delineate atrial structure and function and could contribute to a personalized care pathway for atrial fibrillation patients. The imaging modality offers excellent spatial resolution and has been utilised in pre-, peri- and post-procedural care for patients with atrial fibrillation. Advances in temporal resolution, acquisition times and analysis techniques suggest potential expanding roles for cardiac computed tomography in the future management of patients with atrial fibrillation. The aim of the current review is to discuss the use of cardiac computed tomography in atrial fibrillation in pre-, peri- and post-procedural settings. Potential future applications of cardiac computed tomography including atrial wall thickness assessment and epicardial fat volume quantification are discussed together with emerging analysis techniques including computational modelling and machine learning with attention paid to how these developments may contribute to a personalized approach to atrial fibrillation management.

Peridevice Leak After Left Atrial Appendage Occlusion: Incidence, Mechanisms, Clinical Impact, and Management

Left atrial appendage occlusion is an increasingly adopted stroke prevention strategy in patients with atrial fibrillation. However, peridevice leaks after the procedure are not infrequent and have recently been shown to confer a higher risk for subsequent ischemic events. In this paper, the authors review the available research on the frequency, mechanisms, clinical significance, and management of peridevice leak after percutaneous left atrial appendage occlusion.

Role of Multimodality Imaging in Transcatheter Structural Interventions

Cardiac imaging is the backbone for safe and optimal transcatheter structural interventions. Transthoracic echocardiogram is the initial modality to assess valvular disorders, while transesophageal echocardiogram is best to delineate the mechanism of valvular regurgitation, preprocedural assessment for transcatheter edge-to-edge repair, and for intraprocedural guidance. Cardiac computed tomography is the modality of choice for assessing calcifications, maneuvering multiplaner reconstruction of different cardiac structures, preprocedural planning for various transcatheter valve replacement, and assessing for hypoattenuated leaflet thickening and reduced leaflet motion. Cardiac magnetic resonance imaging is best known for most accurate volumetric assessment of valvular regurgitation and chamber size quantification. Cardiac positron emission tomography is the only modality that could assess active infection through using fluorine 18 fluorodeoxyglucose radiotracer.

Intra- and Postprocedural Multimodality Imaging in Atrial Fibrillation

Multi-modality imaging plays critical roles during and after procedures associated with atrial fibrillation. Transesophageal echocardiography is an invaluable tool for left atrial appendage occlusion during the procedure and at follow-up. Both cardiac computed tomography and cardiac magnetic resonance contribute to postprocedural evaluation of pulmonary vein isolation ablation. The present review is the second of a 2-part series where we discuss the roles of cardiac imaging in the evaluation and management of patients with atrial fibrillation, focusing on intraprocedural and postprocedural assessment, including the clinical evidence and outcomes data supporting this future applications.

Preprocedural Multimodality Imaging in Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia worldwide and is associated with increased risk of heart failure, stroke, and death. In current medical practice, multimodality imaging is routinely used in the management of AF. Twenty-one years ago, the ACUTE trial (Assessment of Cardioversion Using Transesophageal Echocardiography) results were published, and the management of AF changed forever by incorporating transesophageal echocardiography guided cardioversion of patients in AF for the first time. Current applications of multimodality imaging in AF in 2022 include the use of transesophageal echocardiography and computed tomography before cardioversion to exclude left atrial thrombus and in left atrial appendage occlusion device implantation. Transesophageal echocardiography, cardiac computed tomography, and cardiac magnetic resonance are clinically used for AF ablation planning. The decision to use a particular imaging modality in AF is based on patient's characteristics, guideline recommendation, institutional preferences, expertise, and cost. In this first of 2-part review series, we discuss the preprocedural role of echocardiography, computed tomography, and cardiac magnetic resonance in the AF, with regard to their clinical applications, relevant outcomes data and unmet needs, and highlights future directions in this rapidly evolving field.

The use of cardiac computed tomography angiography in the assessment of percutaneous left atrial appendage closure - Review and experts recommendations endorsed by the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle

Atrial fibrillation is the most common cause of arrhythmia which is responsible for over 15% of ischemic strokes, most of these being secondary to migration of a left atrial appendage (LAA) thrombus. In patient with contraindication to anticoagulant therapy, percutaneous closure system placement may be indicated. Cardiac computed tomography (CT) angiography plays a central role in the initial assessment as well as in the follow-up. The purpose of the pre-implantation cardiac CT angiography is to evaluate the anatomy of the LAA in order to select the most suitable prosthesis and check for any contraindication to device implantation. Image analysis is divided into four steps that include analysis of the approach; search for a thrombus in the LAA; investigation of the anatomy of the LAA (morphology of the LAA, dimensions of the LAA and choice of device) and cardiac and thoracic assessments. Follow-up involves CT examination to check for correct placement of the device and to detect any complications. On the basis of the results of currently available published research, a panel of experts has issued recommendations regarding cardiac CT angiography prior to percutaneous LAA closure device placement, which were further endorsed by the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV).