Effects of blood pressure on the prothrombotic risk in 1235 patients with non-valvular atrial fibrillation

Background: Increased levels of plasma von Willebrand factor (vWf, an index of endothelial damage/dysfunction) and soluble P-selectin (sP-sel, an index of platelet activation) concentrations have been reported as indices of the prothrombotic state in both non-valvular atrial fibrillation and hypertension separately. However, the effect of hypertension on the levels of these indices in the setting of atrial fibrillation, and whether increasing severity of hypertension presents an additive prothrombotic risk, is unclear. Methods: Plasma concentrations of vWf and sP-sel were measured by ELISA in 1235 patients with atrial fibrillation, and levels related to a history of hypertension and rising quartiles of systolic, diastolic and pulse pressure in those with and without diabetes mellitus and prior vascular events. Results: Mean plasma vWf was higher among patients with atrial fibrillation with a history of hypertension (149 vs 145 IU/dl, p = 0.005). Also, an increase in the levels of vWf with increasing quartiles of pulse pressure (p = 0.042) was noticed. However, on multivariate analysis, after adjusting for potential confounders, the effects of both hypertension and pulse pressure became non-significant (p = 0.261 and p = 0.5, respectively). Levels of sP-sel were unaffected by a history of hypertension and rising quartiles of systolic and diastolic blood pressure, or pulse pressure. Conclusion: Among patients with atrial fibrillation, patients with hypertension have higher vWf levels, indicating endothelial damage/dysfunction, which is associated with increasing pulse pressure. However, these associations are probably owing to the presence of other associated cardiovascular disease, rather than hypertension itself. Furthermore, platelet activation (sP-sel) was unrelated to hypertension or blood pressure in this atrial fibrillation cohort. Hypertension or blood pressure levels do not seem to have an independent additive affect on the prothrombotic state in atrial fibrillation.