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Effect of Warfarin on Thrombin Generation Parameters in Elderly Patients with Atrial Fibrillation

1University of São Paulo Medical School - Coagulation Laboratory - Hospital das Clínicas, Sao Paulo, Brazil, 2University of São Paulo Medical School - Interdisciplinary Medicine in Cardiology - Heart Institute (InCor), Sao Paulo, Brazil, 3Stago, Sao Paulo, Brazil

Abstract Number: PB0386

Meeting: ISTH 2021 Congress

Theme: Diagnostics and OMICs » Laboratory Diagnostics

Background: Despite the availability of direct oral anticoagulants, warfarin is still widely used and is the only option for patients with mechanical heart valves or end-stage renal disease.
Measurement of international normalized ratio (INR) for prothrombin time is the standard for warfarin-dosage adjustment and little is known about the value of thrombin generation (TG) test in this context.

Aims: We conducted this study to analyze the effect of warfarin on TG and the correlation between its parameters and INR. 

Methods: Our local ethics committee approved the protocol. We included 25 patients on warfarin therapy for atrial fibrillation (AF), with age above or equal to 70 years,  and 25 controls, with age above or equal to 70yrs and AF without anticoagulant.
We measured thrombin generation using an automated system (ST Genesia) and its results were compared between groups. For warfarin-treated patients, we also measured INR and analyzed its relation to TG parameters: lag time, time to peak, peak, and endogenous thrombin potential (ETP).

Results: Warfarin significantly increased lag time: 2.83 (IQR: 2.57-4.48) vs 1.53 (IQR: 1.38-1.74), p<0.001 and time to peak: 4.29 (IQR: 3.96-6.14) vs 2.84 (IQR: 2.54 – 3.36), p < 0.001, and significantly decreased thrombin peak 108.8 (IQR: 83.67 – 139.25) vs 304.5 (IQR 245.85 – 329.10), p < 0.001, and endogenous thrombin potential (ETP): 417.7 (IQR: 323.4 – 507.45) vs 1086 (IQR 870 – 1255), p<0.001. We observed a significant linear correlation between INR and ETP [ ρ Spearman – 0.627 (-0.823 a -0.297) p<0.001], INR and Peak [R Pearson -0.642 (-0.823 a -0.319) p=0.001], and no significant correlation between INR and Lagtime [ρ Spearman + 0.297 (-0.124 a 0.627) p=0.150] or INR and time to Peak [ρ Spearman +0.228 (-0.196 a +0.580) p=0.273].

Conclusions: Although warfarin alters each parameter of the TG test, only ETP and thrombin peak significantly correlate with INR. 

To cite this abstract in AMA style:

Rocha TR, Pastana A, D`Amico E, Villaça P, Yu P, Magalhães I, Cardozo FA, Franco L, Lustosa G, Caramelli B, Calderaro D. Effect of Warfarin on Thrombin Generation Parameters in Elderly Patients with Atrial Fibrillation [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/effect-of-warfarin-on-thrombin-generation-parameters-in-elderly-patients-with-atrial-fibrillation/. Accessed December 6, 2023.

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