Changes in fibrinolytic activity and coagulation factors after epicardial left atrial appendage closure in patients with atrial fibrillation

Background: The left atrial appendage (LAA) is known to be the primary source of thrombus formation in atrial fibrillation (AF). We investigate whether epicardial LAA occlusion (LAAO) from the cardiovascular system has an effect on coagulation and prothrombotic status in AF. Methods: Twenty-two patients with nonvalvular AF, who were not currently receiving oral anticoagulation (OAC) therapy, participated in a single-center prospective study. We measured fibrinogen and plasminogen levels along with plasma fibrin clot permeability, clot lysis time (CLT) and endogenous thrombin potential (ETP) before the LAAO procedure, at discharge and 1 month afterward. Results: One month after the LAAO procedure, plasma fibrin clot permeability improved by 39.3% as measured by clots prepared from peripheral blood (P=0.019) and also after adjustment for fibrinogen (P=0.027). Higher plasma fibrin clot permeability was associated with improved clot susceptibility to lysis (r=-0.67, P=0.013). CLT was reduced by 10.3% (P=0.0020), plasminogen activator inhibitor-1 antigen levels were reduced by 52% (P=0.023) and plasminogen activity was increased by 8.9% (P=0.0077). A trend toward decreased thrombin generation, reflected by a decreased ETP and peak thrombin generated was also observed 1 month after LAAO procedure (P=0.072 and P=0.087, respectively). No differences were observed in tissue-type plasminogen activator and thrombin-activatable fibrinolysis inhibitor plasma levels (both P>0.05). Conclusions: Obtained results seem to confirm that LAA plays a key role in thrombogenesis. Elimination of LAA from the circulatory system may improve fibrin clot permeability and susceptibility to fibrinolysis in peripheral blood.