Background The CHA²DS²VASc score is established and recommended for the risk stratification of stroke in patients with atrial fibrillation (AF) based on clinical parameters. How this relates to haematological characteristics, in particular global thrombotic status is unknown.
Methods We assessed the thrombotic status of 80 patients with newly diagnosed AF (61% male, 72 ± 12 yrs), who were divided into 3 groups according to CHA²DS²VASc score (Group I: 0–1, Group II: 2–3, Group III: ≥4). Assessment of thrombotic status was performed using the Global Thrombosis Test (GTT), an automated, point-of-care test that assesses both platelet reactivity and endogenous thrombolysis from a native, non-anticoagulated blood sample. The time taken to form an occlusive thrombus under high shear stress (occlusion time, OT), and the time required to restore flow through endogenous thrombolysis (lysis time, LT) were measured at baseline and after being established on stable anticoagulation.
Results Overall CHA²DS²VASc score was 2.9 ± 1.7. There were 21 patients in Group I, 29 in Group II, and 30 in Group III. Anticoagulation prolonged OT (419 ± 122s vs. 584 ± 153s; p = 0.00001), and reduced LT (1939 ± 829s vs. 1625 ± 934s; p = 0.03). At baseline, there was no difference between the 3 groups with respect to OT (Group I: 412 ± 98s, Group II: 434 ± 149s, Group III: 408 ± 110s; p = 0.7), or LT (Group I: 1778 ± 537s, Group II: 1879 ± 747s, Group III: 2108 ± 1038s; p = 0.3). Following anticoagulation, OT was similar in the 3 groups (Group I: 561 ± 148s, Group II: 582 ± 155s, Group III: 602 ± 157s; p = 0.7), and LT was also similar (Group I: 1265 ± 846s, Group II: 1734 ± 817s, Group III: 1775 ± 1050s; p = 0.1). There was no difference in the relative change (∆) in OT (Group I: 149 ± 169s, Group II: 148 ± 129s, Group III: 193 ± 126s; p = 0.4) or LT (Group I: -514 ± 1002s, Group II: -117 ± 928s, Group III: -333 ± 1229s; p = 0.4) between the 3 groups in response to anticoagulation.
Conclusions The CHA²DS²VASc score does not appear to reflect global thrombotic status either before or after anticoagulation. Whilst the CHA²DS²VASc score is incredibly useful in assessing populations at risk, it may not be an accurate reflection of the underlying thrombotic status of an individual.
- CHADS2 score
- Atrial fibrillation
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