Left Atrial Appendage Eccentricity and Irregularity Are Associated With Residual Leaks After Percutaneous Closure

Left atrial appendage occlusion: On the need of a numerical model to simulate the implant procedure

Left atrial appendage occlusion (LAAO) is a percutaneous procedure to prevent thromboembolism in patients affected by atrial fibrillation. Despite its demonstrated efficacy, the LAA morphological complexity hinders the procedure, resulting in postprocedural drawbacks (device-related thrombus and peri-device leakage). Local anatomical features may cause difficulties in the device's positioning and affect the effectiveness of the device's implant. The current work proposes a detailed FE model of the LAAO useful to investigate implant scenarios and derive clinical indications. A high-fidelity model of the Watchman FLX device and simplified parametric conduits mimicking the zone of the LAA where the device is deployed were developed. Device-conduit interactions were evaluated by looking at clinical indicators such as device-wall gap, possible cause of leakage, and device protrusion. As expected, the positioning of the crimped device before the deployment was found to significantly affect the implant outcomes: clinician's choices can be improved if FE models are used to optimize the pre-operative planning. Remarkably, also the wall mechanical stiffness plays an important role. However, this parameter value is unknown for a specific LAA, a crucial point that must be correctly defined for developing an accurate FE model. Finally, numerical simulations outlined how the device's configuration on which the clinician relies to assess the implant success (i.e., the deployed configuration with the device still attached to the catheter) may differ from the actual final device's configuration, relevant for achieving a safe intervention.

Left atrial appendage closure for stroke prevention in atrial fibrillation patients: A promise that came true

Anticoagulation therapy plays a crucial role in the management of atrial fibrillation (AF), considering the high morbidity and mortality of AF-related ischemic strokes. With the plausible hypothesis that left atrial appendage is the main source of thrombus in AF patients, left atrial appendage closure (LAAC) has been regarded as a potential substitute to oral anticoagulation in order to meet the unmet needs for stroke prevention, particularly in patients with high bleeding risk. Notable advancements in safety, efficacy, and device innovation have been made in recent years, albeit concerns still remain regarding the insufficient efficacy data, device-related complications, and the need for procedural optimization. We aim to review current knowledge about LAAC and provide potential future directions for the remaining key issues.

Transition from WATCHMAN V.2.5 to WATCHMAN FLX for closure of the left atrial appendage: echocardiographic and clinical findings

INTRODUCTION

Interventional closure of the left atrial appendage (LAAC) has been established as an alternative treatment for patients with atrial fibrillation (AF) and an elevated risk of stroke. The WATCHMAN FLX (WM FLX) as the newest WATCHMAN LAAC device differs in several technical characteristics from its precursor, the WATCHMAN V.2.5 (WM V.2.5).

METHODS

The data presented here are derived from a retrospective single-centre study. All patients in which an LAAC was performed between February 2017 and March 2021 with either a WM V.2.5 or WM FLX device were included.

RESULTS

169 patients were included in this study, of whom 95 had been treated with WM V.2.5 and 74 with WM FLX, respectively. Directly after implantation, only minor differences regarding membrane thickness and connector protrusion were noted, whereas no relevant differences were found regarding device sizing, device compression or peridevice leakage, respectively. However, at 3-month follow-up, device compression was significantly reduced in WM FLX indicating a continued device expansion which was paralleled by a reduced number of peridevice leakage in comparison to WM V.2.5. Additionally, the combined clinical endpoint of death, stroke/transistoric ischaemic attack, tamponade, device embolisation, device-related thrombosis or peridevice leakage was reduced in WM FLX.

CONCLUSION

LAAC using the WM FLX device results in a continued device expansion over the first 3 months based on differences in radial force in comparison to WM V.2.5. This is accompanied by a reduction in adverse clinical endpoints.

Pre-procedural determination of device size in left atrial appendage occlusion using three-dimensional cardiac computed tomography

The complex structure of the left atrial appendage (LAA) brings limitations to the two-dimensional-based LAA occlusion (LAAO) size prediction system using transesophageal echocardiography. The LAA anatomy can be evaluated more precisely using three-dimensional images from cardiac computed tomography (CT); however, there is lack of data regarding which parameter to choose from CT-based images during pre-procedural planning of LAAO. We aimed to assess the accuracy of measurements derived from cardiac CT images for selecting LAAO devices. We retrospectively reviewed 62 patients with Amplatzer Cardiac Plug and Amulet LAAO devices who underwent implantation from 2017 to 2020. The minimal, maximal, average, area-derived, and perimeter-derived diameters of the LAA landing zone were measured using CT-based images. Predicted device sizes using sizing charts were compared with actual successfully implanted device sizes. The mean size of implanted devices was 27.1 ± 3.7 mm. The perimeter-derived diameter predicted device size most accurately (mean error = − 0.8 ± 2.4 mm). All other parameters showed significantly larger error (mean error; minimal diameter = − 4.9 ± 3.3 mm, maximal diameter = 1.0 ± 2.9 mm, average diameter = − 1.6 ± 2.6 mm, area-derived diameter = − 2.0 ± 2.6 mm) than the perimeter-derived diameter (all p for difference < 0.05). The error for other parameters were larger in cases with more eccentrically-shaped landing zones, while the perimeter-derived diameter had minor error regardless of eccentricity. When oversizing was used, all parameters showed significant disagreement. The perimeter-derived diameter on cardiac CT images provided the most accurate estimation of LAAO device size regardless of landing zone eccentricity. Oversizing was unnecessary when using cardiac CT to predict an accurate LAAO size.

Percutaneous Occlusion of the Left Atrial Appendage with Thrombus Irresponsive to Antithrombotic Therapy

We analyzed clinical experience with percutaneous closure of instances of left atrial appendage with thrombus (LAAT) irresponsive to antithrombotic therapy in patients treated in three high-volume cardiology centers. Clinical and procedural data regarding consecutive patients who underwent percutaneous left atrial appendage closure (PLAAC) due to LAAT were retrospectively analyzed. The study population consisted of 17 patients (11 men; 68 ± 14 years; CHA₂DS₂VASC 4.7 ± 1.9; HASBLED 3 (0-5)) with LAAT confirmed by transesophageal echocardiography, and included 5 patients with mechanical heart valves. Most of the patients (94.1%) received anticoagulation therapy before PLAAC. All LAATs were located in distal portions of the appendage and occupied less than 30% of its volume. Occluding-device implantation was successful in 17 patients; in one, a residual leak was disclosed. Appropriate positioning of occluders required more than 1 attempt in 6 individuals (35.3%); in 3 others (17.6%), the subjects' devices had contact with thrombi. No procedural complications were noted. Midterm follow-up (median: 10 months) revealed no procedure-related complications or clinically diagnosed thromboembolism. Transesophageal echocardiography (TEE) performed after six months revealed device-related thrombus in one patient. We concluded that LAAT irresponsive to antithrombotic therapy might be effectively treated with PLAAC, even in patients with mechanical-valve prostheses.

Morphology of the Left Atrial Appendage: Introduction of a New Simplified Shape-Based Classification System

BACKGROUND

The left atrial appendage (LAA) is a heart structure with known prothrombogenic and pro-arrhythmogenic properties.

AIM

The aim of this study was to evaluate the specific anatomy of the LAA and to create a simple classification system based on the shape of its body.

METHOD AND RESULTS

This study investigated 200 randomly selected autopsied human hearts (25.0% females, 46.6±19.1 years old). Three (3) types of LAAs were distinguished: the cauliflower type (no bend, limited overall length, compact structure [36.5%]); the chicken wing type (substantial bend in the dominant lobe [37.5%]), and the arrowhead type (no bend, one dominant lobe of substantial length [26.0%]). Additional accessory lobes were present in 55.5% of all LAAs. Significant variations between category types were noted in LAA length (chicken wing: 35.7±9.8 mm, arrowhead: 30.8±10.1 mm, cauliflower: 22.3±9.6 mm [p<0.001]) and in the thickness of pectinate muscles located within the LAA apex (arrowhead: 1.2±0.7 mm; cauliflower: 1.1±0.6 mm; chicken wing: 0.9±0.6 mm [p<0.001]). Left atrial appendage volume and orifice size were not affected by the type of LAA shape. The age of the donor was positively correlated with LAA volume (r=0.29, p=0.005), body length (r=0.26, p=0.012), and area of the orifice (r=0.36, p<0.001). Donors with an oval LAA orifice were significantly older than those with round orifices (50.2±16.6 vs 43.7±20.4 years [p=0.014]) and had significantly heavier hearts (458.2±104.8 vs 409.6±114.1g [p=0.002]).

CONCLUSIONS

This study delivered a new simple classification system of the LAA based on its body shape. An increase in age and heart weight was associated with LAA enlargement and a more oval-shaped orifice. Results of current study may help to estimate the different thrombogenic properties associated with each LAA type and be an assistance during planning and performing interventions on LAA.

Incidence, risk factors, and clinical impact of peridevice leak following left atrial appendage closure with the LAmbre device-Data from a prospective multicenter clinical study

BACKGROUND

In the present study, we sought to explore the incidence, risk factors, and clinical impact of peridevice leaks (PDLs), following LAmbre-assisted left atrial appendage closure (LAAC).

METHODS

We performed transesophageal echocardiography (TEE) on patients participating in the LAmbre multicenter study, at Day 1 postimplantation, then at 3 and 12 months to assess PDL, device-related thrombus, left atrial appendage (LAA) thrombus, and left atrial thrombus. Clinical events were recorded during follow-up.

RESULT

A total of 152 patients with atrial fibrillation successfully completed LAAC. At 3 months follow-up, 123 patients underwent TEE, with 21 (17%) of them presenting PDL. Among the 121 patients who underwent TEE at 12 months follow-up, 19 (15.7%) presented PDL. Patients with PDL exhibited larger LAA orifice diameters and larger device sizes compared to those in the no leak group. In addition, we found no significant differences in thromboembolic events between patients in the PDL and no leak groups.

CONCLUSION

LAmbre-assisted LAA closure resulted in a relatively low PDL occurrence, and its rate decreased over time. In addition, PDL was more prominent in patients with larger LAA orifice diameter and larger device size. However, the condition was not associated with an increased risk for thromboembolic events.

Reference value of perimeter-derived diameter assessed by three-dimensional transesophageal echocardiography in left atrial appendage occluder size selection

BACKGROUND

The aim of this study was to investigate the utility of perimeter-derived diameter (PDD) measured by three-dimensional (3D) transesophageal echocardiography (TEE) in predicting the size of left atrial appendage (LAA) occluder.

METHODS AND RESULTS

Left atrial appendage landing zone diameter (LZD) was measured by two-dimensional (2D) TEE, 3DTEE, and digital subtraction angiography (DSA) as LZD-2Dmax, LZD-2Dmean, LZD-3Dmax, LZD-3Dmean, LZD-PDD, LZD-DSAmax, respectively, before and during transcatheter LAA closure with Watchman devices in 100 patients. A difference of one or more device size intervals between the predicted size and the size actually implanted was defined as mismatching. Seventy-eight patients were followed up by TEE to obtain occluder compression ratio. The correlation between LZD and the final implanted occluder size was 0.559, 0.641, 0.754, 0.760, 0.782, and 0.848 for LZD-2Dmax, LZD-2Dmean, LZD-3Dmax, LZD-3Dmean, LZD-PDD and LZD-DSAmax, respectively (P < .001). Matching ratio between the size predicted by retrospective measurements of LZD and the device size actually implanted was 65%, 57%, 66%, 63%, 70%, and 83% for LZD-2Dmax, LZD-2Dmean, LZD-3Dmax, LZD-3Dmean, LZD-PDD and LZD-DSAmax, respectively. There was no significant difference in LZD value, matching ratio, and compression ratio between the patients with eccentric and noneccentric LAA landing zone (P > .05). Compression ratio of the mismatching subjects was higher than that in the matching subjects when evaluated by LZD-2Dmean, LZD-3Dmean, and LZD-PDD (P < .05).

CONCLUSIONS

Landing zone diameter derived from LAA perimeter measured by preprocedure 3DTEE showed reference value for LAA occluder size selection, providing superior correlation and matching ratio with the final implanted size and indicating the adjustment of oversizing.

CT sizing for left atrial appendage closure is associated with favourable outcomes for procedural safety

Aims

We evaluated the utility of computerized tomography (CT) with respect to sizing work-up for percutaneous left atrial appendage (LAA) closure, and implications for procedural safety and outcomes.

Methods and results

Contrast-enhanced multi-detector CT was routinely conducted to guide sizing for LAA closure in addition to transoesophageal echocardiography (TOE). Procedural safety and efficacy were prospectively assessed. Across 73 consecutive cases there were no device-related procedural complications, and no severe leaks. Systematic bias in orifice sizing by TOE vs. CT was significant on retrospective analysis (bias -3.0 mm vs. maximum diameter on CT; bias -1.1 mm vs. mean diameter on CT). Importantly, this translated to an altered device size selection in more than half of all cases, and median size predicted by CT was one interval greater than that predicted by TOE (27 mm vs. 24 mm). Of particular note, gross sizing error by TOE vs. CT was observed in at least 3.4% of cases. Degree of discrepancy between TOE and CT was correlated with LAA orifice eccentricity, orifice size, and left atrial volume. Mean orifice size by CT had the greatest utility for final Watchman device-size selection.

Conclusions

In this single-centre registry of LAA closure, routine incorporation of CT was associated with excellent outcomes for procedural safety and absence of major residual leak. Mean orifice size may be preferable to maximum orifice size. A particular value of CT may be the detection and subsequent avoidance of gross sizing error by 2D TOE that occurs in a small but important proportion of cases.