Depth of device implantation in left atrial appendage occlusion (LAAO) is an independent risk factor for device-related thrombus (DRT), in which deeper, larger implantation predicts a higher likelihood of DRT, a new study shows. These data were reported by Pedro Cepas-Guillén, MD, PhD, of the Hospital Clinic de Barcelona, Spain; Eduardo Flores-Umanzor, MD, PhD, of Toronto General Hospital, and colleagues, in a manuscript published Wednesday online in JACC: Cardiovascular Interventions. The implantation procedure for LAAO continues to be studied, as LAAO is recommended for stroke prevention in some patients who experience nonvalvular atrial fibrillation. This patient group is at increased risk for thromboembolic events, especially DRT. Antithrombotic treatment is available, but modifiable treatment factors are sought for reducing the incidence of DBT. The investigators of this study analyzed the outcomes of LAAO device implantation depth and sought to determine the significance of LAAO in the occurrence of DRT. Device depth characteristics—such as length, area and angle of the implantation—were retrospectively collected from the LAAO-specific database at each of the nine participating centers in Europe and Canada. Patient outcomes were also evaluated at follow-up. The primary endpoint of the study was how device depth impacted the occurrences of DRT, proximal or distal. Patients (n=1,317) who underwent successful LAAO were classified into two groups: proximal (55%, mean age=75±10 years, 63.1% male) and distal device (45%, mean age=74.8±12 years, 65.6% male) implantation. The proximal implantation patients were classified by the covered pulmonary ridge (PR) in the lobe and disc cohort, or <5 mm from the PR in the single-lobe cohort. The distal implantation patients were classified by uncovered PR in the disc and lobe cohort and ≥5 mm in the single-lobe cohort. There were no between-group differences in the procedural outcomes. At follow-up, lower incidence of DRT was observed in patients from the proximal implantation group (2.3%) than in the distal implantation group (12.2%; p<0.001). Patients who had larger uncovered left atrial appendage and deeper device implantation experienced higher rates of DRT (p<0.001), and the type of device did not impact this outcome. Distal implantation (hazard ratio [HR]=1.62; 95% confidence interval [CI]=3.39-10.36) and no or single antiplatelet therapy (HR=1.62; 95% CI=0.99-2.62) were also independent predictors of DRT, shown by multivariable analysis. The investigators noted that the primary limitation of this study was the observational design, which brings along an inherent bias for the analyzed variables. In addition, each of the nine sites reported the clinical and imaging results, so cases were re-evaluated if they were doubtful. All nine sites did not have the same procedural volume. Finally, clinical endpoints need to be carefully interpreted, and investigators in follow-up studies may want to consider other important variables in their analyses. Overall, depth of device implantation in LAAO was an independent risk factor for DRT, and deeper device implantation and larger left atrial appendage areas were associated with greater occurrence of DRT. In an accompanying editorial, Martin W. Bergmann, MD, and Felix Meincke, MD, of Asklepios Klinik Altona, Hamburg, Germany, discussed left atrial appendage closure (LAAC) and its current uses, as all as similar therapies. They also noted some areas for research improvement. “New concepts like reduced DOAC dosing in combination with LAAC are being studied, with continued questions of monotherapy and even no therapy for high-risk patients,” the editorialists wrote. They and applauded the authors of the new study—as well as other, similar studies—for providing the LAAC research field with factors in the prevention of DRT. “Given the low clinical event rate even in the presence of DRT expected to currently occur in about 3% to 5% of patients in most trials, LAAC can be regarded as a safe procedure that requires close follow-up in the first year,” the editorialists concluded. Sources: Cepas-Guillén P, Flores-Umanzor E, Leduc N, et al. Impact of Device Implant Depth After Left Atrial Appendage Occlusion. JACC Cardiovasc Interv. 2023 Aug. 9 (Article in Press). Bergmann MW, Meincke F. Improving Left Atrial Appendage Closure: Reducing the Risk of Device-Related Thrombus. JACC Cardiovasc Interv. 2023 Aug. 9 (Article in Press). Image Credit: Pepermpron - stock.adobe.com