Impact of left atrial appendage closure on circulating microvesicles levels: The MICROPLUG study

Area of Science:

• Cardiovascular Medicine
• Hematology
• Biomedical Engineering

Background:

• Left atrial appendage occlusion (LAAO) is an alternative to anticoagulation for preventing embolism in non-valvular atrial fibrillation (NVAF).
• Microvesicles (MVs) are cell-derived particles with diverse biological roles.
• The left atrial appendage (LAA) may be a source of MVs during atrial fibrillation (AF), but the effect of LAAO on circulating MVs is unknown.

Purpose of the Study:

• To investigate the impact of LAAO on circulating microvesicle levels.
• To determine if LAAO influences procoagulant, endothelial, platelet, red blood cell, or leukocyte-derived MVs.
• To explore the potential local production of MVs within the LAA.

Main Methods:

• A prospective study included 25 patients undergoing LAAO and 25 controls.
• Blood samples were collected pre-procedure, 48 hours post-procedure, and at 6 weeks for LAAO patients.
• Flow cytometry was used to measure circulating MVs, including AnnV+, procoagulant, endothelial, platelet, RBC, and leukocyte-derived MVs.

Main Results:

• LAAO significantly increased AnnV+, platelet, RBC, and leukocyte MVs post-procedure.
• Elevated RBC-MVs and AnnV+ MVs persisted at 6 weeks in LAAO patients.
• Leukocyte and CD62e+ endothelial MVs were higher in the LAA compared to the pulmonary vein, suggesting local production.

Conclusions:

• LAAO alters circulating MV levels, potentially inducing a mild pro-coagulant status.
• Erythrocyte activation may occur during the initial weeks post-LAAO due to device healing.
• The LAA itself may contribute to increased MV production, particularly leukocytes and endothelial MVs.