• LAA Closure Device Clots: Yes or No to Anticoagulation?

    Little known about balancing thromboembolic bleeding risks in these individuals

    The clinical significance of device-related thrombus after left atrial appendage (LAA) closure suggests the importance of close surveillance after diagnosis, even if the right antithrombotic regimen for these patients remains elusive, investigators found.

    In the Amulet Observational Study, 1.7% of the 1,088 patients who had LAA occlusion done with the Amplatzer Amulet subsequently developed thrombus formation on the surface of the device in the first year, according to Adel Aminian, MD, of Centre Hospitalier Universitaire de Charleroi in Belgium, and colleagues.

    • Cardiovascular death, ischemic stroke, or transient ischemic attack (TIA): 29.4% vs 7.2% for peers without Amulet-related thrombus (HR 4.10, 95% CI 1.64-10.25)
    • Ischemic stroke or TIA: 17.6% vs 3.0% (HR 5.27, 95% CI 1.58-17.55)
    • Ischemic stroke: 18.3% vs 2.6% (P<0.01)


    Given its associations with adverse events, the discovery of a device-related thrombus on echocardiography or CT suggests the importance of close clinical monitoring, the investigators emphasized.

    Matthew Price, MD, of Scripps Clinic in La Jolla, California, similarly advocated for comprehensive serial imaging surveillance upon the diagnosis of a device-related thrombus, suggesting 1 year post-implant or even longer in an accompanying editorial.

    As for who might be at greater risk, Aminian and colleagues found that age was not a significant predictor of Amulet-related thrombus, but a larger LAA orifice was (HR 1.09, 95% CI 1.00-1.19).

    More than 80% of individuals who developed this kind of clot did not have the Amulet disc covering the left upper pulmonary vein (PV) ridge, "indicating suboptimal implantation," the group said. Device-related clots tended to develop "near the superior edge of the Amulet disc close to the PV ridge, with an uncovered PV ridge as a potential contributing factor," they added.

    The thrombus group in the study had been discharged mostly with dual antiplatelet therapy (DAPT), but still got anticoagulants more frequently than their peers.

    "DRT presents a difficult patient management scenario, as 83% of enrolled patients were contraindicated to OAC [0ral anticoagulation] and 72% had a history of major bleeding. Fortunately, no major bleeds occurred in patients following DRT, as 83% received anticoagulants to resolve the thrombus," Aminian and colleagues commented.

    The findings from Aminian's group "provide a degree of comfort that Amulet LAA closure is associated with a low rate of DRT in a cohort of well-followed patients predominantly treated with antiplatelet therapy post-implantation. Their results also suggest that Amulet operators should be cognizant to try and cover the pulmonary venous ridge with the proximal disk of the device, if possible. However, their findings must be interpreted with several caveats," according to Price.

    He pointed out that DRT is found on imaging and was likely underestimated in the study due to detection bias resulting from missing follow-up imaging in 10% of cases, "ad hoc" imaging in 41% of the DRT events, and a lack of transesophageal echocardiography (TEE) in more than half of patients at the time of stroke.


    The investigators also cautioned that their findings may not be generalizable to other LAA occlusion devices.

    No matter the device, however, the point of transcatheter LAA closure is to eliminate the clot risk in patients who are not optimal candidates for oral anticoagulation, Price said.

    "DRT is therefore of deep concern for implanters and patients: re-institution of prolonged anticoagulation can be problematic in patients at very high bleeding risk when DRT is identified on routine follow-up imaging, and it is 'too little too late' when it is identified after a patient suffers a thromboembolic event," according to the editorialist.

    Furthermore, it's unclear if DAPT and non-vitamin K antagonist oral anticoagulant (NOAC) regimens are really the safe alternatives to warfarin given that the data suggesting so were observational, according to a JACC:Cardiovascular Interventionsreview by Jacqueline Saw, MD, of Vancouver General Hospital.

    "The diagnosis of DRT will require anticoagulation for a period of at least a month exposing these patients to potential life-threatening bleeding. Thus, the cure may become worse than the disease if DRT is not adequately prevented by an antithrombotic treatment that may be tolerated by these patients," Montalescot and Guedeney said in an accompanying editorial.

    Ongoing trials that may help pin down the best discharge medication regimen following LAA occlusion include ANDES, ASAP-TOO, Amulet IDE, STROKE-CLOSE, and CLOSURE-AF.


    The Amulet study was funded by Abbott.

    Saw disclosed relevant relationships with AstraZeneca, Abbott Vascular, Boston Scientific, Servier, St. Jude Medical, and Sunovion.

    Aminian disclosed relevant relationships with Abbott and Boston Scientific.

    Montalescot disclosed support (institutional) from and relevant relationships with Abbott, Amgen, Actelion, AstraZeneca, Bayer, Boehringer Ingelheim, Boston-Scientific, Bristol-Myers Squibb, Beth Israel Deaconess Medical, Brigham Women's Hospital, the Cardiovascular Research Foundation, Daiichi Sankyo, Idorsia, Lilly, Europa, Elsevier, Fédération Française de Cardiologie, ICAN, Medtronic, Journal of the American College of Cardiology, Lead-Up, Menarini, MSD, Novo Nordisk, Pfizer, Sanofi, Servier, The Mount Sinai School, the TIMI Study Group, and WebMD.

    Guedeney disclosed no relevant relationships with industry.

    Price disclosed relevant relationships with Boston Scientific, Medtronic, Abbott Vascular, W.L. Gore, and AstraZeneca, as well as support (institutional) from Daiichi Sankyo.


    JACC: Cardiovascular Interventions

    Source Reference: Saw J, et al "Antithrombotic therapy and device-related thrombosis following endovascular left atrial appendage closure" JACC Cardiovasc Interv 2019.

    JACC: Cardiovascular Interventions

    Source Reference: Aminian A, et al "Incidence, characterization, and clinical impact of device-related thrombus following left atrial appendage occlusion in the prospective global AMPLATZER Amulet observational study" JACC Cardiovasc Interv 2019.

    JACC: Cardiovascular Interventions

    Source Reference: Montalescot G and Guedeney P "Left atrial appendage closure: Only a question of bleeding!" JACC Cardiovasc Interv 2019.

    JACC: Cardiovascular Interventions

    Source Reference: Price MJ "Device-related thrombus after transcatheter left atrial appendage closure" JACC Cardiovasc Interv 2019.



    Read the original article on Medpage Today:  LAA Closure Device Clots: Yes or No to Anticoagulation?

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