Anticoagulant therapy after prosthetic valve replacement -optimal PT-INR in Japanese patients-.

Values of the international normalized ratio of prothrombin time (PT-INR) were analyzed at the time when anticoagulant-related complications developed in patients undergoing prosthetic valve replacement so as to evaluate the optimal therapeutic range in PT-INR value in Japanese patients. A total of 102 patients with a prosthetic heart valve who have been followed up at our department during the past 25 years were enrolled in this study. PT-INRs were determined regularly in these patients for the period between October 1996 and March 1999. Although no thromboembolic complications occurred during the period of this study, hemorrhagic complications developed in 26 (25.5%) patients. Three (2.9%) patients suffered from life threatening bleeding, such as cerebral bleeding and gastrointestinal bleeding and were defined as the major hemorrhagic group. Another 23 (22.5%) patients had minor bleeding complications such as nasal, gingival or subcutaneous bleeding and were defined as the minor hemorrhagic group. Mean PT-INR values were 3.8 2.0 and 3.2 1.0 at the onset of the complications in major and minor hemorrhagic groups, respectively, and there was no significant difference between the two groups. However, mean PT-INR values in the minor bleeding group differed significantly from that in a patient group with no hemorrhagic complications (N=76). Among the cases with bleeding complications, only 19% of the patients belonged to the range below 2.5 of PT-INR value and 54% of the patients were included in the range from 2.5 to 3.5 (p<0.05). In conclusion, the optimal therapeutic range between 2.5 and 3.5 in PT-INR recommended by the American Heart Association for patients with a prosthetic heart value in Western countries may be too high in Japanese patients. PT-INR below 2.5 is considered to be safe to prevent hemorrhagic complications.