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Catheter Ablation in Combination With Left Atrial Appendage Closure for Atrial Fibrillation
Published on: February 26, 2013
A cross-sectional and diurnal study of thrombogenesis among patients with chronic atrial fibrillation
F L Li-Saw-Hee1, A D Blann, G Y Lip
1University Department of Medicine, City Hospital, Birmingham, United Kingdom.
Insights
Patients with chronic atrial fibrillation (AF) exhibit a persistent hypercoagulable state without diurnal variation in key hemostatic factors. This sustained prothrombotic condition may increase stroke risk.
Area of Science:
- Cardiology
- Hematology
- Thrombosis Research
Background:
- Atrial fibrillation (AF) increases stroke and thromboembolism risk.
- AF is linked to hypercoagulability, affecting thrombosis, platelet activation, and endothelial function.
- Cardiovascular events like myocardial infarction involve thrombosis, which can show diurnal variation.
Purpose of the Study:
- To investigate diurnal variation in hemostatic factors in chronic AF patients.
- To compare levels of soluble thrombomodulin (sTM) and soluble P-selectin (sP-sel) in AF patients versus sinus rhythm controls.
- To assess endothelial function and platelet activation markers in AF.
Main Methods:
- Studied 52 chronic AF patients (no antithrombotic therapy) and matched controls.
- Measured plasma fibrinogen, sP-sel, sTM, and von Willebrand factor (vWF) levels.
- Collected serial blood samples from a subgroup over 24 hours to assess diurnal changes.
Main Results:
- AF patients showed elevated plasma sP-sel, sTM, vWF, and fibrinogen compared to controls.
- Significant correlations were observed between fibrinogen and sP-sel in both AF and control groups.
- No significant diurnal variation was found for sP-sel, sTM, vWF, or fibrinogen in the 24-hour study.
Conclusions:
- Chronic AF patients do not exhibit circadian or diurnal variation in their hypercoagulable state.
- Persistent hypercoagulability and lack of diurnal variation in hemostatic markers in AF may elevate stroke and thromboembolic risk.
- Findings highlight the continuous prothrombotic nature of chronic AF.
Objectives:
First, we sought to determine whether there is diurnal variation in hemostatic factors related to thrombogenesis and hypercoagulability among patients with chronic atrial fibrillation (AF). Second, we sought to determine whether levels of soluble thrombomodulin (sTM), a marker of endothelial function, or soluble P-selectin (sP-sel), an index of platelet activation, are altered in patients with AF as compared with subjects in sinus rhythm.
Background:
Atrial fibrillation is associated with an increased risk of stroke and thromboembolism and is known to confer a hypercoagulable state, with abnormalities of thrombosis, platelet activation and endothelial cell function. Many cardiovascular events, such as acute myocardial infarction, have thrombosis as an underlying process, and they undergo diurnal variation.
Methods:
Fifty-two patients (45 men, mean [+/- SD] age 66 +/- 6 years) with chronic AF, none of whom received antithrombotic therapy, were studied. Baseline levels of fibrinogen, sP-sel, sTM and von Willebrand factor (vWF) were compared to those levels in matched healthy control subjects in sinus rhythm. In a subgroup of 20 patients, five venous blood samples were collected through an indwelling cannula at 6-h intervals from 12 PM to 12 PM the following day and were analyzed for the same markers.
Results:
Patients with chronic AF had higher plasma sP-sel, sTM, vWF and fibrinogen levels as compared with control subjects in sinus rhythm. Significant correlations were found between fibrinogen and sP-sel in patients with AF (r = 0.567 [Spearman], p < 0.001) and in control subjects (r = 0.334, p = 0.016). There was no significant diurnal variation in plasma levels of sP-sel, sTM, vWF or fibrinogen over the 24-h study period (repeated measures analysis of variance, p = NS).
Conclusions:
There is no circadian or diurnal variation in the hypercoagulable state seen in AF, as assessed by plasma fibrinogen and markers of platelet (sP-sel) and endothelial function (vWF and sTM). The persistent hypercoagulable state, together with the loss of diurnal variation in various hemostatic markers, in chronic AF may contribute to the high risk of stroke and thromboembolic complications in these patients.
