A variety of platelet function tests were performed in patients with four forms of obstructive cerebrovascular disease (CVD); transient ischemic attacks (TIA), reversible ischemic neurological deficit (RIND), cerebral infarct, and cerebral embolism of cardiac source in rheumatic valvular heart disease (RVHD). Platelet studies included platelet aggregation induced by ADP and ristocetin, spontaneous platelet aggregation, von Willebrand factor (VIII:vWF), platelet aggregation enhancing factor (PAEF), and percentage of large platelets (megathrombocytes). Serial testing was carried out in acute stroke patients. The effect of aspirin therapy was also evaluated. A clear difference in results was observed between patients with cardiogenic embolism and those with other forms of CVD. In patients with TIA, RIND, and cerebral infarct, platelet aggregation, both induced and spontaneous, was enhanced along with elevation of plasma VIII:vWF and PAEF, and increased percentage of megathrombocytes. In patients with cardiogenic embolism, however, these studies were negative except for percent megathrombocytes. This value was increased in the embolic patients with RVHD in comparison with non-embolic patients with RVHD. Increase in platelet aggregation to ADP and percent megathrombocytes developed slowly over a week following stroke. Induced and spontaneous platelet aggregation, and percent megathrombocytes could be normalized with 600 mg aspirin p.o. These studies suggest that a systemic increase of hyperaggregable platelets and of plasma activators of platelet function exists in thrombotic CVD and may be related to its pathogenesis, while local hemodynamic factors may be more important in the thrombogenesis of cardiogenic embolism.

The preventive effect of statins on coronary events is not only associated with the cholesterol-lowering effect of these drugs, but also various direct effects on the vascular wall, which include improvement of endothelial function, antioxidant activity, and anti-inflammatory activity. We investigated whether short-term statin therapy could improve arterial stiffness and assessed its mechanism of action in patients with hypercholesterolemia. We assessed arterial stiffness in 10 patients (mean age: 62.9 +/- 9.0 years) with hypercholesterolemia (total cholesterol > or =220 mg/dl). The patients were treated with cerivastatin (0.15 mg/day) for 4 weeks. Before and after 4 weeks of treatment, we determined arterial stiffness from brachial-ankle pulse wave velocity and the ankle-brachial blood pressure index (ABI) using a FORM apparatus (Colin, Komaki, Japan). We also measured the blood levels of high-sensitivity C-reactive protein (hsCRP) and malondialdehyde low-density lipoprotein (MDA-LDL) as markers of inflammation and oxidation, respectively. After statin therapy, both the right and left abPWV were significantly decreased from 1544.6 +/- 157.1 to 1349.0 +/- 223.9 cm/s and from 1592.1 +/- 164.8 to 1424.8 +/- 245.2 cm/s, respectively (P < 0.05). However, the ABI was unchanged after 4 weeks of cerivastatin therapy. MDA-LDL decreased significantly (from 161.2 +/- 42.4 to 119.4 +/- 33.5 U/l, P < 0.05) and hsCRP also decreased. Total cholesterol and LDL-cholesterol decreased, while triglycerides and high-density lipoprotein-cholesterol were unchanged. Blood pressure was not significantly altered from the baseline value by statin therapy. These results suggest that the preventive effect of statins on coronary events is partly associated with the various actions of these drugs on the vascular wall, and that statins are not only cholesterol-lowering agents but also antiatherosclerotic agents.

The thrombotest (TT) technique has been widely used in Japan for monitoring oral anticoagulant therapy (OAT). The therapeutic range was originally recommended to be 10%-25%. However, the International Committee for Standardization in Hematology/International Committee on Thrombosis and Hemostasis (ICSH/ICTH) recommended using the international normalized ratio of prothrombin time (PT-INR) for monitoring OAT. It is necessarv to use a universal standard measure for monitoring OAT in accordance with the ICSH/ISTH recommendation. We simultaneously measured TT and PT in blood samples from 1,157 patients on long-term warfarin therapy, and studied the correlation between TT and PT-INR. An excellent linear correlation was obtained between TT-INR and PT-INR with the regression equation PT-INR = 1.0420 TT-INR - 0.0987 (r = 0.905, P < 0.001). We also examined the correlation between the incidence of thromboembolism in 170 patients receiving warfarin therapy after prosthetic valve replacement; 50.5% received concomitant antiplatelet therapy. Thromboembolism occurred in 9 of 170 patients during a mean follow-up period of 2.44 years. The average TT values in patients with and without thromboembolism were 26.4% (PT-INR: 1.53) and 21.1% (1.73), respectively (P < 0.01). The incidence of thromboembolism did not differ significantly between patients on warfarin alone (average TT: 22.2%) and those on warfarin and antiplatelet agent (average TT: 20.9%). Our results suggest that the incidence of thromboembolism is low in Japan despite a less intensive regimen having been adopted.

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