Acceptability of Low Intensity Anticoagulation Therapy after Mechanical Heart Valve Replacement

Kim, Jong Woo; Rhie, Sang Ho; Kim, Young Chun; Yang, Junho; Jang, In Seok; Choi, Jun Young

Abstract

BACKGROUND: The long-term administration of oral anticoagulant to the patients with a mechanical heart valve prosthesis is mandatory. However, the appropriate intensity of oral anticoagulant therapy to prevent thromboembolic or hemorrhagic complications is still controversial. We tried to apply low intensity anticoagulant therapy for which the International Normalized Ratios ranged between 1.5 and 2.5, and we analyzed the anticoagulation-related long term outcomes. MATERIAL AND METHOD: From January 1992 to December 2002, 144 patients who underwent a single cardiac valve replacement were included in the study, and their ages ranged from 15 to 72 years (mean age: 47.4+/-15.1): there were 49 aortic valve replacements (AVR) and 95 mitral valve replacements (MVR). The patients were followed up monthly or bi-monthly at the outpatient clinic with clinical examinations and measuring the prothrombin time to adjust the International Normalized Ratios (INRs) within the low-intensity target range between 1.5 and 2.5. RESULT: The follow-up period was 835.3 patient-years (mean: 5.9+/-3.5) and the INRs of 7,706 measurements were available for evaluation. The mean INRs of the aortic and the mitral valve replacement groups were significantly different (p<0.01). All the patients' INRs were within the target range in 61.9% of the measurements. The mean INRs (2.16+/-0.23) of the patients with atrial fibrillation, which was found in 30.3% of the patients, were definitely higher than those (2.03+/-0.27) measured in the patients with regular rhythm (p<0.01). Thromboembolic episodes occurred in 9 patients with an incidence of 1.08%/patient-year. Major bleeding occurred in 2 patients (MVR) with an incidence of 0.24%/patient-year. The patients who displayed better compliance showed a lower incidence of complications (p=0.000).
CONCLUSION
The anticoagulation therapy with a low-intensity target range after MVR or AVR seems to be effective and feasible, and increasing the patients' compliance should be done for achieving more effective anticoagulation therapy.