Initial evaluation of reasonableness of target INR 1.60 to 2.20 and warfarin weekly dosage adjustment in patients after mechanical heart valve replacement

Objective To evaluate the reasonableness of anticoagulation management strategy in patients after mechanical heart valve replacement. Methods All patients were followed and registered continually at outpatient clinic from July 2011 to February 2013, with a minimum of 6 months after surgery. Targeted international normalized rate (INR) 1.60 to 2.20 and warfarin weekly dosage adjustment were used as the strategy of anticoagulation management. Except bleeding, thrombogenesis and thromboembolism, time in therapeutic range (TTR) and fraction of TTR (FTTR) were adopted to evaluate the quality of anticoagulation management. Results A total 1 442 patients and 6 461 INR values were included for data analysis. The patients had a mean age of 48.2��10.6 years (14-80 years) and the following up time were 6 to 180 months (39.2��37.4 months) after surgery. Of these patients, 1 043 (72.3%) was female and 399 (27.7%) was male. INR values varied from 0.90-8.39 (1.85��0.49) and required weekly doses of warfarin were 2.50-61.25 (20.89��6.93 mg). TTR of target INR and acceptable INR were 51.1% (156 640.5 days / 306 415.0 days), 64.9% (198 856.0 days / 306 415.0 days), respectively. FTTR of target INR and acceptable INR were 49.4% (3 193 times / 6 461 times), 62.6% (4 047 times / 6 461 times). There were 8 major bleeding events, 7 mild bleeding events, 2 thromboembolism events, and 2 thrombogenesis in the left atrium. Conclusion It is reasonable to use target INR 1.60-2.20 and warfarin weekly dosage adjustment for patients after mechanical heart valve replacement. ? 2014 Editorial Board of Chin J Evid-based Med.