Medline ® Abstracts for References 8,14,46,47
of 'Perioperative management of patients receiving anticoagulants'
Perioperative management of antithrombotic therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.
Douketis JD, Spyropoulos AC, Spencer FA, Mayr M, Jaffer AK, Eckman MH, Dunn AS, Kunz R, American College of Chest Physicians
Chest. 2012;141(2 Suppl):e326S.
BACKGROUND: This guideline addresses the management of patients who are receiving anticoagulant or antiplatelet therapy and require an elective surgery or procedure.
METHODS: The methods herein follow those discussed in the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines. Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines article of this supplement.
RESULTS: In patients requiring vitamin K antagonist (VKA) interruption before surgery, we recommend stopping VKAs 5 days before surgery instead of a shorter time before surgery (Grade 1B). In patients with a mechanical heart valve, atrial fibrillation, or VTE at high risk for thromboembolism, we suggest bridging anticoagulation instead of no bridging during VKA interruption (Grade 2C); in patients at low risk, we suggest no bridging instead of bridging (Grade 2C). In patients who require a dental procedure, we suggest continuing VKAs with an oral prohemostatic agent or stopping VKAs 2 to 3 days before the procedure instead of alternative strategies (Grade 2C). In moderate- to high-risk patients who are receiving acetylsalicylic acid (ASA) and require noncardiac surgery, we suggest continuing ASA around the time of surgery instead of stopping ASA 7 to 10 days before surgery (Grade 2C). In patients with a coronary stent who require surgery, we recommend deferring surgery>6 weeks after bare-metal stent placement and>6 months after drug-eluting stent placement instead of undertaking surgery within these time periods (Grade 1C); in patients requiring surgery within 6 weeks of bare-metal stent placement or within 6 months of drug-eluting stent placement, we suggest continuing antiplatelet therapy perioperatively instead of stopping therapy 7 to 10 days before surgery (Grade 2C).
CONCLUSIONS: Perioperative antithrombotic management is based on risk assessment for thromboembolism and bleeding, and recommended approaches aim to simplify patient management and minimize adverse clinical outcomes.
Department of Medicine, McMaster University, Hamilton, ON, Canada.
Management of anticoagulation before and after elective surgery.
Kearon C, Hirsh J
N Engl J Med. 1997;336(21):1506.
McMaster University and Hamilton Civic Hospitals Research Centre, ON, Canada.
Temporary discontinuation of warfarin therapy: changes in the international normalized ratio.
White RH, McKittrick T, Hutchinson R, Twitchell J
Ann Intern Med. 1995;122(1):40.
OBJECTIVE: To measure the rate of decrease of the international normalized ratio (INR) after temporary discontinuation of warfarin therapy.
DESIGN: Prospective evaluation of an outpatient cohort.
SETTING: University medical center anticoagulation clinic.
PATIENTS: 22 patients receiving a fixed evening dose of warfarin for whom temporary discontinuation of therapy was deemed safe.
MEASUREMENTS: Serial plasma samples were drawn for INR measurements approximately 20, 65, 115, and 185 hours after patients received the last dose of warfarin. In five patients, INR was measured twice daily for 5 days.
RESULTS: For patients with a mean steady-state INR of 2.6, the mean INR 65 hours (2.7 days) after discontinuation of warfarin therapy was 1.6 (range, 1.11 to 2.16); 20 of 22 patients (91%) had an INR greater than 1.2. The mean INR 115 hours (4.7 days) after discontinuation of warfarin therapy was 1.1; 5 of 22 patients (23%) had an INR of 1.2 or greater. In 5 patients studied in detail, the INR decreased exponentially and had a half-life that ranged from 0.52 to 1.2 days; the onset of maximal decrease began 24 to 36 hours after discontinuation of warfarin therapy. In the total cohort, age was a significant (P<0.005) independent predictor of smaller decreases in the INR between day 1 and day 3 (regression coefficient = -6.8% +/- 2%/2 days per decade of age; R2 = 0.34).
CONCLUSIONS: By simulating preoperative discontinuation of warfarin therapy, we found that the INR decreases exponentially, with wide interpatient variation in the rate of decrease. Age is associated with a slower rate of decrease. To be certain that the INR at the time of the surgery is less than 1.2, warfarin should be withheld for 96 to 115 hours (4 doses) in patients with a steady-state INR between 2.0 and 3.0. For patients with a higher steady-state INR, a longer wait is necessary.
University of California, Davis.
A feasibility study of continuing dose-reduced warfarin for invasive procedures in patients with high thromboembolic risk.
Larson BJ, Zumberg MS, Kitchens CS
BACKGROUND: The management of perioperative anticoagulation therapy for patients having a high risk of thromboembolism who are receiving long-term oral anticoagulant therapy is uncertain. The prevalent approach is to discontinue oral anticoagulation therapy and initiate heparin therapy. Another potential strategy is to continue oral anticoagulation therapy with a temporary adjustment of warfarin intensity to a preoperative international normalized ratio (INR) of 1.5 to 2.0. Such moderate-dose anticoagulation therapy with warfarin has been shown to be hemostatically safe yet effective in the prevention of thromboembolism after hip or knee replacement.
METHODS: Over an 11-year period (ie, 1993 to 2003), our hemostatic consultative service prospectively identified 100 consecutive patients for whom we continued warfarin therapy at adjusted doses during the perioperative period, targeting a goal for the INR of 1.5 to 2.0. Patients were assigned a score for venous thromboembolic risk as well as overall surgical risk using published instruments. Score assignment was based on what was deemed to be extremely high risk for thromboembolism in patients who were receiving long-term warfarin therapy. Although the patients were accrued prospectively, the final retrospective analysis was made after all patients were treated.
RESULTS: The most common indication (62%) for high-risk assignment was a thromboembolic event within the past 6 months. The second most prevalent reason was prior postoperative venous thromboembolism (VTE) [11%]. Indications for long-term anticoagulation therapy were recent VTE (62%), inherited thrombophilia (7%), antiphospholipid syndrome (13%), mechanical heart valves (18%), and prior cerebrovascular accident (4%). The prevalence of inherited thrombophilia probably has been grossly underestimated, as neither factor V Leiden mutation nor prothrombin 20210 mutation had been described during the bulk of the accrual time. Most surgical procedures (58%) were significantly invasive (Johns Hopkins category 3 to 5). The mean INR values were 2.1 on the day prior to surgery (SD, 0.9594; range, 1.2 to 6.5; n = 65), 1.8 on the day of surgery (SD, 0.4899; range, 1.2 to 4.9; n = 75), and 1.8 on the first postoperative day (SD, 0.4436; range, 1.1 to 3.3; n = 70). Two patients had major bleeding, and four patients had minor bleeding. One patient developed deep venous thrombosis. Several weeks after surgery, one patient with a prosthetic heart valve died from an embolic stroke, which was associated with a failure to increase his anticoagulation to therapeutic levels.
CONCLUSIONS: Moderate-intensity anticoagulant therapy with warfarin, targeting a goal INR of 1.5 to 2.0, appears to be a safe and feasible method for preventing thromboembolic complications in high-risk surgical patients who are receiving long-term oral anticoagulant therapy. This may be considered a reasonable method to afford thromboprophylaxis in highly selected patients who are occasionally seen in clinical practice. This observationalstudy does not prove equality, let alone superiority, to other proposed methods of anticoagulation therapy.
Division of Hematology/Oncology, Department of Medicine, University of Florida, Gainesville, FL, USA.