Medium and long-term follow-up in Chinese patients receiving low intensity warfarin anticoagulation treatment with low International Normalized Ratio (INR) after mechanical mitral valve replacement

Anticoagulation therapy was generally used in patients receiving mechanical mitral valve replacement. However, due to the increased risk of bleeding of anticoagulation therapy, it is important to control the International Normalized Ratio (INR) in a lower range to decrease the risk of bleeding. Therefore, the aim of this study was to investigate to which level the INR should be controlled and explore a suitable intensity of anticoagulation in Chinese Han population after mechanical mitral valve replacement. The experience of low INR anticoagulation using warfarin will also be summarized. We retrospectively recruited 747 patients who underwent mechanical cardiac mitral valve replacement in our institute. All of the patients received oral warfarin anticoagulation therapy with a target INR between 2.0 and 2.5 as the intensity of anticoagulation. Throughout the duration of follow-up, anticoagulation intensity reflected by INR and incidence of complications related to anticoagulation were analysed. The recruited patients were followed up for 6 to 135 months with an overall follow-up rate of 94.1% and a total of 1669.4 patient-years. Ten cases (0.60% patient-years) of cerebral emboli were diagnosed during the follow-up. Haemorrhage secondary to anticoagulation was observed in 39 cases (2.34% patient-years). A low INR oral warfarin anticoagulation therapy achieved satisfactory clinical effects with a low incidence of thromboembolism in Chinese Han population undergone mechanical mitral valve replacement. Thus, there may be room for reducing the intensity of anticoagulation to decrease the incidence of haemorrhagic complications in these patients.