Decreasing warfarin sensitivity during the first three months after heart valve surgery: Implications for dosing

INTRODUCTION: Vitamin K antagonists are prescribed to prevent thromboembolic complications after heart valve surgery. In our experience, patients often show a progressive decrease in sensitivity to warfarin after surgery making it difficult to reach and maintain a therapeutic International Normalized Ratio (INR). We sought to confirm our clinical impression and to gather data for the development of a guide to dosing these patients. MATERIALS …