Abstract 11301: Antithrombotic Effects of Losartan in Hypertensive Patients Complicated with Atrial Fibrillation
Background Angiotensin receptor blockers (ARB) are widely used for hypertension. It was reported that one of ARB losartan had antiplatelet, anticoagulant and profibrinolytic effects experimentally. These properties could be desirable for hypertensive patients with high atherothrombotic and/or thromboembolic risk. Actually losartan reduced cardiovascular events in patients with hypertension complicated with left ventricular hypertrophy in the LIFE study. Furthermore, a LIFE sub study elucidated that its effects were more significant in atrial fibrillation (AF) cases.
Methods and Results To examine antithrombotic effects of losartan on subjects with higher thrombotic risk, consecutive 20 hypertensive patients complicated with AF were included into this study. The patients were treated with losartan 50mg for 8 weeks followed by 100mg for 4 weeks. Blood samples were obtained from each patient 0 (Pre), 4 and 8 weeks after the treatment. Platelet aggregability (small platelet aggregates generation speed; SPA), CD62 positive platelets (CD62(+) plts), tissue factor (TF) and von Willebrand factor (vWF) antigens, type1 plasminogen activator inhibitor (PAI-1) activity and P-selectin levels were measured. Plasma levels of TF, vWF and P-selectin were measured by ELISA kits. Plasma PAI-1 activity were measured by a chromogenic single point poly-D-lysine stimulated assay kit. CD62(+) plts were measured by flow cytometry. Platelet aggregability was measured with PA-200 (Kowa Company, Ltd., Tokyo, Japan). Results were summarized in the table below.
Conclusions Losartan inhibited platelet activity dose-dependently in hypertnsive patients complicated with AF. Fibrinolytic capacity and coagulation proteins also changed toward less thrombogenicity. Therefore, losartan has possibility to inhibit arterial thrombus formation in hypertensive patients with AF and could be advantageous to avoiding cardiovascular events in those patients. Table.
- © 2011 by American Heart Association, Inc.