Elevated thrombin generation levels in the left atrial appendage in patients with atrial fibrillation

Background: Atrial Fibrillation (AF) is the most common sustained tachi-arrhythmia. Thrombus formation in the left atrial appendage (LAA) increases the risk of stroke and systemic embolism in patients with AF. Objectives: The aim of this study was to compare thrombin generation in the LAA to the LA among patients with AF. Methods: A cross-sectional study of consecutive patients with AF undergoing pulmonary veins catheter ablation. Blood samples from the femoral vein (FV), right atrium (RA), left atrium (LA), and LAA were collected during the catheter ablation procedures. Thrombin generation was assessed by a Calibrated Automated Thrombogram. The LAA-calibrated automated thrombogram parameters were compared with the RA, LA, and FV. Results: A total of 47 consecutive patients were enrolled in the study. The endogenous thrombin potential and peak height were significantly higher in the LAA compared with the LA, the mean differences and 95% CI between the LA and LAA were -378.9 (-680.5, -77.2) (nM∗min) and -66.7 (-119.6, -13.8) (nM) in the endogenous thrombin potential and peak height respectively. Conclusion: In patients with AF undergoing catheter ablation, the LAA demonstrated increased thrombin generation compared with the LA. This finding might contribute to the understanding of why the LAA is more predisposed to thrombus formation than the LA. Clinical Trials Registration: NCT03795883.