Paroxysmal Atrial Fibrillation: Insight Into the Intimate Mechanisms of Coagulation.

Background: Atrial fibrillation (AF) is a hypercoagulable state. However, the intimate mechanisms leading to impaired coagulation and the timing of their activation are unclear. The aim of the study was to investigate the factors that initiate the coagulation cascade in the early hours (up to 48 h) of clinical manifestation of paroxysmal atrial fibrillation (PAF).

Methods: Tissue factor (TF) level, coagulation activity of factor VII (FVIIa), factor XII (FXIIa) and factor XI (FXIa) were measured in plasma of 51 non-anticoagulated patients (26 men and 25 women, aged 59.84 ± 11.42 years) and 52 controls (26 men and 26 women, aged 59.50 ± 10.53 years) by enzyme-linked immunoassays and kinetic assays.

Results: TF was higher in the PAF group (268.63 ± 90.62 pg/mL vs. 170.21 ± 66.19 pg/mL, P < 0.001) as well as FVIIa (170.82±59.39% vs. 95.17±37.90%, P < 0.001), FXIIa (218.31±84.04% vs. 148.41±53.94%, P < 0.001) and FXIa (178.41±55.94% vs. 111.75±37.33%, P < 0.001). Regression analysis showed that in the first 6 h of the disease, increase in time led to increase in FXIIa (r = 0.25, P < 0.05), FXIa (r = 0.75, P < 0.05), TF level (r = 0.25, P < 0.05) and FVIIa (r = 0.25, P < 0.05).

Conclusion: Hemocoagulation changes were observed even < 6 h after the onset of the disease. They suggest that PAF has an early tendency for hypercoagulability, with the involvement of the intrinsic and extrinsic pathways of coagulation.