Optimal therapeutic range for oral anticoagulants in Japanese patients with prosthetic heart valves: a preliminary report from a single institution using conversion from thrombotest to PT-INR.
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.
Uetsuka
Y
Y
Department of Cardiology, The Heart Institute of Japan, Tokyo Women's Medical University. yoshiou@aol.com
Hosoda
S
S
Kasanuki
H
H
Aosaki
M
M
Murasaki
K
K
Ooki
K
K
Inoue
M
M
Akiyama
E
E
Kitada
M
M
D000284:Administration, Oral; D000328:Adult; D000925:Anticoagulants / Q000008:administration & dosage*; D005260:Female; D006350:Heart Valve Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D011517:Prothrombin Time; D018570:Risk Assessment; D013923:Thromboembolism / Q000188:drug therapy* / Q000209:etiology*
D000925:Anticoagulants