It is known that the plasma level of thrombin-antithrombin-III complex (TAT) is significantly increased in patients with valvular heart diseases including mitral stenosis [32] and aortic stenosis [33], atrial fibrillation [34], and idiopathic cardiomyopathy [35], implying a state of increased coagulability in these heart diseases. The gene discussed is SERPINC1; the disease is atrial fibrillation.