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The WATCHMAN Left Atrial Appendage Closure Device for Atrial Fibrillation
Published on: February 28, 2012
Observations on clot properties in atrial fibrillation: Relation to renal function and choice of anticoagulant
Ahsan A Khan1, Lewis J Hardy2, Eduard Shantsila1
1Institute of Applied Health Research, University of Birmingham, United Kingdom.
Insights
New oral anticoagulants (NOACs) alter blood clot properties differently than warfarin in atrial fibrillation (AF) patients. Worsening kidney function in warfarin users prolongs clot breakdown, potentially increasing thrombosis risk.
Area of Science:
- Cardiology
- Hematology
- Pharmacology
Background:
- Atrial fibrillation (AF) increases stroke and thromboembolism risk.
- Renal impairment is common in AF patients, affecting bleeding and clotting risks.
- Oral anticoagulants are crucial for AF management.
Purpose of the Study:
- To compare how different oral anticoagulants (warfarin vs. NOACs) affect plasma clot properties.
- To investigate the impact of progressive renal dysfunction on clot properties in AF patients on warfarin.
Main Methods:
- Studied 257 AF patients on oral anticoagulants and 192 AF patients on warfarin grouped by eGFR.
- Prepared platelet-poor plasma and monitored clot formation and fibrinolysis kinetically for 1 hour.
Main Results:
- Dabigatran and rivaroxaban showed slower clot formation rates compared to warfarin.
- Warfarin prolonged the time between 50% clotting and 50% lysis versus NOACs.
- Worsening renal function (eGFR) significantly prolonged fibrinolysis time in warfarin-treated patients.
Conclusions:
- NOACs modulate coagulation and fibrinolysis differently than warfarin ex vivo.
- Progressive renal dysfunction in AF patients on warfarin extends fibrinolysis, potentially elevating thrombosis risk.
Introduction:
Atrial fibrillation (AF) is associated with increased risk of stroke and thromboembolism. Patients with AF have a higher incidence of renal impairment, which may influence the risks of systemic thromboembolism or bleeding. We determined how different oral anticoagulants affect plasma clot properties and whether progressive renal dysfunction affects plasma clot properties in patients on warfarin.
Materials And Methods:
We studied 257 patients with AF receiving oral anticoagulants. Furthermore, we recruited 192 separate patients with AF on warfarin and divided them in 4 groups based on estimated glomerular filtration rate (eGFR). Platelet poor plasma was prepared and clot formation and fibrinolysis was monitored kinetically up to 1 h.
Results:
Rate of clot formation was significantly slower with dabigatran and rivaroxaban. Time between 50% clotting and 50% lysis was prolonged in patients receiving warfarin compared to NOACs. Time to 50% lysis from maximum absorbance was significantly shorter in patients receiving rivaroxaban. Time between 50% clotting and 50% lysis became significantly prolonged with worsening eGFR. Time to 50% lysis from maximum absorbance was prolonged as renal function worsened.
Conclusions:
Compared to warfarin, NOACs differently modulate coagulation and fibrinolysis under ex vivo conditions. Worsening renal function in AF patients on warfarin prolongs fibrinolysis, potentially increasing the risk of thrombosis.
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