The clinical significance of beta-thromboglobulin (β-TG) and platelet factor 4 (PF-4) levels were evaluated in 26 patients with atrial fibrillation (af) complicated by valvular heart disease (VHD), 73 patients with of but without valvular heart disease and 57 normal subjects. The β-TG level was significantly higher in af patients without VHD than in normal subjects (49.4±35.8ng/ml vs 31.2±14.0ng/ml, p<0.01) and in af patients with VHD than in normals (64.1±52.8ng/ml vs 31.2±14.0ng/ml, p<0.01). Af patients with or without VHD tended to show high levels of PF4 compared with normals (af patients without VHD: 34.1±45.5ng/ml, af patients with VHD: 18.6±27.2ng/ml, normals: 11.6±8.2ng/ml). There was no correlation between β-TG levels and age in af patients without VHD or in normals. There was also no correlation between β-TG levels and heart rate in af patients without VHD.
The activation of platelets was suggested in patients with atrial fibrillation on the basis of increased levels of platelet releasing substances, especially in those with VHD. The high levels of β-TG and PF4 in patients with atrial fibrillation may be one explanation for the high incidence of thromboembolism in these patients, indicating the necessity of antiplatelet therapy.