Rebuttal with regards to “Device-associated thrombus formation after left atrial appendage occlusion: A systematic review of events reported with the Watchman, the Amplatzer Cardiac Plug and the Amulet”

Challenges and advances in device-related thrombus in left atrial appendage occlusion

Oral anticoagulation therapy (OAC) is a mainstay for mitigating stroke and other embolic events in patients with atrial fibrillation (AF). Despite the demonstrated efficacy of OAC in reducing events, many patients are unable to tolerate OAC due to bleeding risks. Left atrial appendage occlusion (LAAO) devices were developed as implantable technologies to moderate stroke risk in patients with intolerance to OAC. Despite clinical data supporting near-comparable protection against thromboembolic events with OAC, device-related thrombus formation has emerged as a critical complication following LAAO that remains a potential limitation to the safety and efficacy of LAAO. Improved biocompatibility of LAAO devices with fluoropolymers, a well-established stent-coating technology used to reduce thrombus formation and promote endothelialization, may optimize outcomes after LAAO.

Left Atrial Appendage Closure: A Narrative Review

Atrial fibrillation (AF) is the most common cardiac arrhythmia and the cause of thromboembolic events in elderly patients worldwide. AF is associated with a significantly increased risk of morbidity and mortality due to cardiac emboli, primarily from left atrial appendage (LAA) thrombus. Oral anticoagulation therapy is the standard treatment to effectively reduce the risk of thromboembolic events in patients with AF. However, anticoagulation treatment increases bleeding risk. LAA closure (LAAC) has recently been introduced as a feasible mechanical preventive intervention for thromboembolic events while minimizing the risk of bleeding. Transcatheter LAAC devices have evolved in the past decade, and several ongoing trials have demonstrated the improvements of safety and outcomes in newer generation devices. This review summarizes the current perspectives and outcomes regarding LAAC as an alternative to pharmacologic therapy.

The role of CT in arrhythmia management-treatment planning and post-procedural imaging surveillance

Several interventional treatment options exist in patients with atrial and ventricular arrhythmia. Cardiac CT is routinely performed prior to occlusion of the left atrial appendage, pulmonary vein isolation, and cardiac device implantation. Besides the evaluation of coronary artery disease, cardiac CT provides isotropic, high-resolution CT images of the cardiac anatomy with the possibility of multiplanar reformations and three-dimensional reconstructions which are helpful to guide interventional treatment. In addition, cardiac CT is increasingly used to rapidly evaluate periprocedural complications and for the routine post-procedural imaging surveillance in patients after interventions. This review article will discuss current applications of pre- and post-interventional CT imaging in patients with arrhythmia.

Heart Team for Left Appendage Occlusion without the Use of Antithrombotic Therapy: The Epicardial Perspective

BACKGROUND

Left atrial appendage occlusion is an increasingly proposed treatment for patients with atrial fibrillation and poor tolerance to anticoagulants. All endovascular devices require antithrombotic therapy. Anatomical and clinical variables predisposing to device-related thrombosis, as well as post-procedural peri-device leaks, could mandate the continuation or reintroduction of aggressive antithrombotic treatment. Because of the absence of foreign material inside the heart, epicardial appendage closure possibly does not necessitate antithrombotic therapy, but data of large series are missing.

METHODS

Multidisciplinary team evaluation for standalone totally thoracoscopic epicardial appendage closure was done in 180 consecutive patients with atrial fibrillation and poor tolerance to antithrombotic therapy. One hundred and fifty-two patients consented (male 66.1%, mean age 76.1 ± 7.4, CHA2DS2VASc mean 5.3 ± 1.6, HASBLED mean 3.8 ± 1.1). Indications were cerebral hemorrhage (48%), gastro-intestinal bleeding (33.3%), and other bleeding (20.7%). No antithrombotic therapy was prescribed from the day of surgery to the latest follow up.

RESULTS

Procedural success was 98.7%. At a mean follow up of 38.2 ± 18.8 months, cardioembolic and bleeding events were 1.3% and 0.6%, respectively. Among patients with a history of blood transfusions (41.1%), none needed further transfusions or treatment post procedure.

CONCLUSION

Epicardial appendage occlusion without any antithrombotic therapy appears to be safe and effective. This strategy could be advised when minimization of bleeding risk concomitant to stroke prevention is needed.

Clinical and echocardiographic risk factors for device-related thrombus after left atrial appendage closure: an analysis from the multicenter EUROC-DRT registry

BACKGROUND

Data on Device-related Thrombus (DRT) after left atrial appendage closure (LAAC) remain scarce. This study aimed to investigate risk factors for DRT from centers reporting to the EUROC-DRT registry.

METHODS

We included 537 patients (112 with DRT and 425 without DRT) who had undergone LAAC between 12/2008 and 04/2019. Baseline and implantation characteristics, anti-thrombotic treatment and clinical outcomes were compared between both groups in uni- and multivariate analyses. Additional propensity-score matching (PSM) was conducted to focus on the role of implantation characteristics.

RESULTS

Patients with DRT showed higher rates of previous stroke/transient ischemic attack (TIA) (49.1% vs. 34.7%, p < 0.01), spontaneous echocardiographic contrast (SEC) (44.9% vs. 27.7%, p < 0.01) and lower left atrial appendage (LAA) peak emptying velocity (35.4 ± 18.5 vs. 42.4 ± 18.0 cm/s, p = 0.02). Occluders implanted in DRT patients were larger (25.5 ± 3.8 vs. 24.6 ± 3.5 mm, p = 0.03) and implanted deeper in the LAA (mean depth: 7.6 ± 4.7 vs. 5.7 ± 4.7 mm, p < 0.01). Coverage of the appendage ostium was achieved less often in DRT patients (69.5% vs. 81.5%, p < 0.01), while DRT patients were less frequently on oral anticoagulation (7.1% vs. 16.7%, p < 0.01). Multivariate analysis identified age, prior stroke/TIA and SEC as independent risk factors for DRT. After PSM, implantation depth was found to be predictive. Rates of stroke/TIA were higher in DRT patients (13.5% vs. 3.8%, Hazard Ratio: 4.21 [95%-confidence interval: 1.88-9.49], p < 0.01).

CONCLUSIONS

DRT after LAAC is associated with adverse outcome and appears to be of multifactorial origin, depending on patient characteristics, anticoagulation regimen and device position.

Device-Related Thrombus After Left Atrial Appendage Closure: Data on Thrombus Characteristics, Treatment Strategies, and Clinical Outcomes From the EUROC-DRT-Registry

[Figure: see text].

Postprocedural Management: Anticoagulation and Beyond

Excluding the left atrial appendage in patients with nonvalvular atrial fibrillation is a mechanical way to decrease stroke risk. During endothelialization, the closure device is exposed to circulating blood, which might activate the coagulation cascade. In excessive proportions, possibly resulting in the development of device-related thrombus, requiring a bridging period with optimal antithrombotic treatment. Initial protocol treatment is less suitable for patients with contraindications to anticoagulation. Less intensive antithrombotic regimens investigated suggest safety and efficacy, however further research is required. A tailored treatment, considering bleeding and thromboembolic risk based on patient/procedural characteristics in every patient, is probably the best approach.

Incidence, Prevention, and Management of Periprocedural Complications of Left Atrial Appendage Occlusion

Major procedural complications related to left atrial appendage occlusion (LAAO) are relatively infrequent but may be associated with major morbidity and mortality. LAAO operators should be knowledgeable about these potential complications. Prompt recognition and treatment are necessary to avoid rapid deterioration and dire consequences. With stringent guidelines on operator training, competency requirements, and procedural-technical refinements, LAAO can be performed safely with low complication rates. This article focuses on commonly used devices, as well as prevention, treatment, and management of complications of LAOO.