Characterizing Clot Microstructure in Atrial Fibrillation and Stroke
Research type
Research Study
Full title
Characterisation of clotting characteristics in atrial fibrillation patients presenting with stroke and their response to anticoagulant treatment
IRAS ID
228596
Contact name
Phillip Adrian Evans
Contact email
Duration of Study in the UK
1 years, 11 months, 31 days
Research summary
Rsearch Summary
Stroke and Atrial fibrillation especially in South Wales are major diseases resulting in a significant social and economic burden. It has long been argued that AF and stroke unfavourably alter how the blood clots, however, there is no available test that can provide a numerical description of blood clotting quality in a clinical setting. The main goal of this observational study is to validate a novel test of clot quality, fractal dimension (df) in atrial fibrillation patients with and without stroke. This study aims to determine whether these patients are more likely to produce substantially modified clots that results in poorer clot quality and how these patients respond to anti coagulation (blood thinning) therapy. To do this a baseline blood sample will be taken for 2 different groups: atrial fibrillation patients suffering a stroke and atrial fibrillation patients without stroke. These patients will then receive oral anticoagulant therapy, following which a second sample will be taken to determine whether they improve clotting quality. The results of the second blood test will be compared to the results of their matched baseline for each participant to ascertain what effect oral anticoagulation has on clotting quality.
Summary Results
120 patients in total were recruited into the study, this included 60 atrial fibrillation (AF) patients and 60 stroke patients with atrial fibrillation. This study has shown that in terms of standard coagulation profile and the GP (gel point) & df (fractal dimension) biomarker both AF and stroke with AF patients did not have a significantly altered or hypercoagulable clotting characteristics. Furthermore, the study indicated that Warfarin whilst providing protection from forming clots (increased TGP) it does have a negative impact on the ability to form stable clots (reduced df). This is shown by the fact that the df in post warfarin patients is far below the minimum value of the healthy range. This would indicate a potential bleeding risk and poor quality coagulation. In contrast Apixaban prolonged clotting (increased TGP) but only slightly reduces df and hence the bloods ability to form stable clots. These results potentially provide a scientific rationale for why historically warfarin is associated with an increased bleeding risk compared to apixaban.
Conclusion
1. df (TGP) can accurately measure the therapeutic effect of apixaban on blood coagulation (kinetic time).
2. df again shows its ability to measure the differing anticoagulant effect of different oral anticoagulants on clot quality.
3. This study would indicate that apixaban has a pronounced anticoagulant effect but has less of a negative impact on the haemostatically forming clot than warfarin which may indicate why apixaban has less bleeding complications than other anticoagulants.
4. This study would indicate that atrial fibrillation per se is not associated with a hypercoagulable state as determined by df.REC name
Wales REC 5
REC reference
17/WA/0236
Date of REC Opinion
9 Aug 2017
REC opinion
Further Information Favourable Opinion