Incidence, Predictors, and Clinical Outcomes of Device-Related Thrombus in the Amulet IDE Trial

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.

Watchman vs. Amulet for Left Atrial Appendage Closure: Current Evidence and Future Perspectives

Left atrial appendage closure (LAAC) is a crucial intervention for stroke prevention in patients with non-valvular atrial fibrillation who are unsuitable for long-term anticoagulation. Amulet and Watchman are the most implanted devices worldwide for performing LAAC, and the aim of this review is to provide a comprehensive comparison focusing on their efficacy, safety, and short- and long-term outcomes. The Watchman device, the first to gain FDA approval, has been extensively studied and demonstrates significant reductions in stroke and systemic embolism rates. The Amulet device, a newer alternative, promises enhanced design features for more efficient appendage sealing. Current data highlight that both devices offer similar efficacy and safety for LAAC. While the two devices differ in terms of intraprocedural complication rates, they offer similar short- to long-term outcomes in terms of peri-device leaks, device-related thrombosis, and mortality. Both devices are indicated for patients who are unable to tolerate OAC, given their similar risk and safety profiles. Newer clinical studies are directed at establishing the efficacy of both devices as the primary method for stroke prevention in AF as an alternative to OAC.

The Association of Hematological Markers with Occurrence of Thrombotic and Bleeding Events following Left Atrial Appendage Occlusion

INTRODUCTION

Patients undergoing left atrial appendage occlusion (LAAO) are at increased risk for bleeding or thromboembolic events. Concurrently, biomarkers are of growing importance in risk stratification for atrial fibrillation patients. We aimed to evaluate the association of hematological markers and clinical characteristics with the occurrence of thromboembolic and bleeding events following LAAO.

METHODS

Seven implanting centers retrospectively gathered data on hematological markers (i.e., platelet count [PC], mean platelet volume [MPV], and fibrinogen) prior to LAAO. Prespecified thromboembolic and major bleeding outcomes were collected and the association with pre-procedural hematological markers and clinical characteristics was evaluated using Cox regression analysis.

RESULTS

In total, 1,315 patients were included (74 ± 9 years, 36% female, CHA2DS2-VASc 4.3 ± 1.5, HAS-BLED 3.3 ± 1.1). Over a total follow-up duration of 2,682 patient years, 77 thromboembolic events and 107 major bleeding events occurred after LAAO. Baseline PC was the only biomarker showing a signal for a relation to thromboembolic events (HR 1.18, 95% CI: 1.00-1.39) per 50*109 increment, p = 0.056). Thrombotic event rates, including device-related thrombus, increased within higher PC quartiles. Thromboembolism was associated with age (HR 1.05, 95% CI: 1.00-1.10, per year increase) and prior thromboembolism (HR 2.08, 95% CI: 1.07-4.03), but with none of the biomarkers in multivariate analysis. No association of any of the hematological markers with major bleeding was observed. Major bleeding following LAAO was associated with prior major bleeding (HR 5.27, 95% CI: 2.71-10.22), renal disease (HR 1.93, 95% CI: 1.17-3.18), and discharge on dual antiplatelet therapy (DAPT) (HR 1.71, 95% CI: 1.05-2.77).

CONCLUSION

Most thrombotic events occurred in the highest PC quartile, but no association of any of the hematological markers with thromboembolism or major bleeding was observed in our analysis. In multivariate analysis, older age and prior thromboembolism were associated with thromboembolism. Prior major bleeding, renal disease and discharge on DAPT were multivariate predictors of major bleeding after LAAO.

Single antiplatelet therapy following Amplatzer left atrial appendage occlusion

BACKGROUND

The optimal antithrombotic therapy following left atrial appendage occlusion (LAAO) remains debated. Ideally, this therapy should effectively prevent device-related thrombosis (DRT) while minimising the associated bleeding risk.

AIMS

We aimed to evaluate the long-term safety and efficacy of a postprocedural single antiplatelet therapy (SAPT) strategy following Amplatzer LAAO in a large consecutive cohort.

METHODS

This retrospective, single-centre, observational study included all patients discharged on SAPT after LAAO with the Amplatzer Cardiac Plug (ACP) or Amplatzer Amulet between March 2010 and December 2021 at Aarhus University Hospital, Denmark. Baseline, procedural, and imaging data were obtained locally, while clinical outcomes and medication data were extracted from the Danish national health registries.

RESULTS

A total of 553 patients underwent Amplatzer LAAO during the specified time frame. Of these, 431 (77.9%) high bleeding risk patients were discharged on SAPT with either acetylsalicylic acid (n=403, 72.9%) or clopidogrel (n=28, 5.1%). At 6 months, 173 (41.7%) patients were not on any antithrombotic therapy. The mean CHA2DS2-VASc and HAS-BLED scores were 3.9±1.5 and 3.4±1.1, respectively. DRT was detected in 6 (1.5%) patients on 8-week follow-up imaging using cardiac computed tomography (n=386, 89.6%) or transoesophageal echocardiography (n=27, 6.3%). The 1-year ischaemic stroke rate was 2.2% (95% confidence interval [CI]: 1.1-4.2). One-year rates for major bleeding and cardiovascular death were 5.9% (95% CI: 4.0-8.9) and 2.9% (95% CI: 1.6-5.1), respectively.

CONCLUSIONS

SAPT following Amplatzer LAAO displayed rates of DRT and stroke comparable to those reported with more intensive antithrombotic regimens. Meanwhile, we observed low rates of major bleeding.

Left Atrial Appendage Occlusion and Post-procedural Antithrombotic Management

Left atrial appendage occlusion (LAAO) is an established alternative to oral anticoagulation for stroke prevention in atrial fibrillation. Antithrombotic therapy is used in the post-procedural period to prevent device-related thrombosis (DRT). The risk of DRT is considered highest in the first 45-90 days after device implantation, based on animal studies of the device healing process. Clinically applied antithrombotic regimens vary greatly across studies, continents, and centers. This article gives an overview of the evidence behind current antithrombotic regimens, ongoing randomized trials, and future post-procedural management.

Left atrial appendage closure: the journey today and tomorrow

PURPOSE OF REVIEW

This review aims to discuss the rationale behind the development of percutaneous LAAC devices as a treatment option for atrial fibrillation patients ineligible for long-term anticoagulation. The evolution of LAAC, from early experiences and challenges to risk mitigation and improved devices and techniques, will be examined. Furthermore, the review will explore our current understanding of the potential and limitations of LAAC in stroke prevention.

RECENT FINDINGS

Multiple trials confirm LAAC device safety and efficacy for stroke prevention, but peri-device leak and thrombus remain concerns postimplantation. Even small leaks pose increased stroke risk. While guidelines suggest short-term anticoagulation postimplant; real-world data show equivalent efficacy with dual antiplatelet regimen.

SUMMARY

LAAC device design has evolved and now serve as a viable option for stroke prevention in high-risk atrial fibrillation patients, offering protection in the absence of anticoagulation.

Impact of Device Implant Depth After Left Atrial Appendage Occlusion

BACKGROUND

Device-related thrombus (DRT) remains one of the main concerns after left atrial appendage occlusion (LAAO). Several risk factors have been proposed, but most cannot be modulated. A modifiable factor such as device implantation depth is a potential target to adjust the risk for DRT.

OBJECTIVES

The aim of this study was to assess the impact of LAAO device implantation depth as a predisposing factor for DRT.

METHODS

The study included patients who underwent successful LAAO at 9 centers in Europe and Canada. Patients were classified into 2 groups: proximal device implantation (covered pulmonary ridge [PR] in the lobe and disc cohort or <5 mm from the PR in the single-lobe cohort) and distal device implantation (uncovered PR in the disc and lobe cohort and ≥5 mm in the single-lobe cohort).

RESULTS

A total of 1,317 patients were included. Among these, proximal and distal device implantation was achieved in 732 (55%) and 585 (45%) patients, respectively. No differences in procedural outcomes were observed between the groups. At follow-up, patients with proximal implantation had a lower incidence of DRT (2.3%) than those with distal implantation (12.2%) (P < 0.001). Deeper device implantation and a larger uncovered left atrial appendage area were associated with a higher incidence of DRT (P < 0.001), regardless of device type. In multivariable analysis, distal implant (HR: 5.92; 95% CI: 3.39-10.36) and no or single antiplatelet therapy (HR: 1.62; 95% CI: 0.99-2.62) emerged as independent predictors of DRT.

CONCLUSIONS

LAAO device implantation depth is an independent risk factor for DRT. Deeper device implantation and larger uncovered left atrial appendage areas were associated with a higher incidence of DRT.