The effect of routine preoperative interruption of dabigatran therapy on coagulation parameters and dabigatran plasma levels in a mixed surgical population.

Dabigatran is an oral anticoagulant used for atrial fibrillation and venous thromboembolism. While an effective antibody reversal agent is available, its cost precludes routine use and the mainstay of preoperative management is timely dabigatran interruption. Unlike warfarin, there are no universally accepted protocols for interruption of dabigatran in the preoperative period and there is uncertainty around the interpretation of standard coagulation tests in the presence of dabigatran. We performed a prospective, observational pilot study in patients presenting for elective surgery to examine: 1) the preoperative plasma dabigatran concentrations on day of surgery associated with the local dabigatran interruption protocol, 2) the potential utility of dabigatran concentrations on day of surgery, and 3) the utility of standard coagulation tests in determining whether dabigatran concentrations were below a 'safe' threshold for surgery. We recruited patients presenting to pre-admission clinics for elective surgery. Dabigatran concentrations below 30 µg/L were considered adequate for proceeding with surgery. Data were obtained and analysed from 21 patients with a median (range) age of 70 (20-86) years. Median (range) dabigatran concentrations on the day of surgery were 5 (0-59) µg/L. Two patients had day of surgery concentrations exceeding 30 µg/L. Of the standard coagulation tests examined, only the thrombin clotting time (TCT) was abnormal for these two patients. Our interruption protocol was associated with safe dabigatran concentrations in most patients on the day of surgery. A minority of patients had dabigatran concentrations above the safe threshold, which were detectable by abnormal TCT results.