Optimal Anticoagulant Therapy after Mechanical Valve Replacement Reviewed in Terms of Activity of Coagulation and Fibrinolysis

(Department of Cardiovascular Surgery, Hachioji Medical Center, Tokyo Medical University, Hachioji, Japan and Second Department of Surgery, Tokyo Medical University*, Tokyo, Japan)

Naoki Konagai Hiromi Yano Mitsunori Maeda
Tatsuhiko Kudo Shin Ishimaru*
Patients with mechanical valve prosthesis must receive long-term oral anticoagulant therapy, thus it is important to set the optimal international normalized ratio of prothrombin time (PT-INR) that effectively prevented thromboembolic complications without excessive bleeding. In this study, anticoagulant therapy was evaluated in terms of the activity of coagulation and fibrinolysis in 137 patients after isolated mechanical valve replacement. With a lower target range of 1.5 -2.0 for the PT-INR, thrombin antithrombin III complex (TAT) increased to more than 3.0 ng/ml in 30 cases, and the activity of coagulation appeared to increase due to insufficient anticoagulant therapy. After the target range was raised to 2.0 -2.5 in all cases, the PT-INR increased significantly from 1.63 to 2.25 (p<0.01) and TAT decreased significantly from 7.58 to 2.81 ng/ml (p<0.01). This showed that activity of coagulation and fibrinolysis was suppressed by high intensity anticoagulation. It is necessary to review the individual activity of coagulation and fibrinolysis to determine the intensity of anticoagulation. We recommend 2.0 -2.5 as the target range for the PT-INR.
@Jpn. J. Cardiovasc. Surg. 33: 9 -12 (2004)