Effect of post‐operative anticoagulation management in patients who have undergone On‐X mechanical heart valve replacement surgery on post‐discharge warfarin therapy

What is known and objective We evaluated the effect of the proportion of time maintained within the target international normalized ratio (INR) postoperatively in hospitalized patients who underwent On‐X mechanical heart valve replacement on warfarin therapy after discharge. Methods Inclusion was patients who were ≥18 years, received warfarin for a minimum of 10 days without any interruptions during hospitalization and followed by the anticoagulation service (ACS) clinic after discharge between June 2006 and June 2016. Patients were excluded if they had incomplete medical records, INR goal changes, known as warfarin resistance, transferred to another facility or expired during the study. The patients were divided into 3 groups according to the proportion of time maintained within therapeutic INR range (TTR) from day 4 to 10 of warfarin initiation (low: