Background
Perioperative management of patients prescribed anticoagulant and/or antiplatelet medications poses a challenge affecting the care of roughly 250,000 patients in the United States annually. In February, the American College of Chest Physicians published updated clinical guidelines to assist physicians with these issues. This and the other articles in the 9th edition of the ACCP Antithrombotic Guidelines are useful sources for patient management regarding thromboembolism diagnosis, prevention, and treatment.
Conclusions
Perioperative anticoagulation management should be based on an assessment of the patient’s risk for venous thromboembolism (VTE) in the context of the risk for bleeding associated with a planned procedure.
No validated model has yet been developed to stratify patients treated with vitamin K antagonists into groups based on their risk for perioperative thrombosis and bleeding. The guideline suggests using a schema that identifies patients at greater than 10% annual risk for VTE as high risk and those at less than 5% annual risk for VTE as low risk, while recognizing that individual patient considerations may be more important than this stratification.
The risk for postoperative VTE associated with a particular procedure is not equivalent to the risk for thromboembolism associated with interruption of antithrombotic therapy, as the potential risk for arterial thrombosis as well as VTE must be considered when coumarins and antiplatelet medications are withheld.
Procedures associated with the highest risk for bleeding when perioperative anticoagulants/antithrombotics are used include urologic procedures; placement of pacemakers and implantable cardioverter defibrillators; endoscopic polypectomy (especially large sessile polyps); procedures on large vascular organs such as the liver, kidney, or spleen; bowel resections, cardiac surgery, major surgeries with tissue injury including joint replacements, cancer surgery, and reconstructive procedures; and intracranial/spinal surgeries.
While not evaluated in randomized trials, a standardized approach to perioperative anticoagulation is recommended in an effort to optimize patient outcomes. Suggestions include perioperative risk assessment at least 7 days prior to the procedure; patient/caregiver education; and medication calendars to optimize compliance; international normalized ratio (INR) measurement 1 day before surgery in patients requiring vitamin K antagonist (VKA) cessation; and routine assessment of postoperative hemostasis before resuming anticoagulants.
Implementation
When vitamin K antagonists must be withheld preoperatively, a 5-day hold interval is recommended. VKA may be resumed when adequate hemostasis is observed at 12-24 hours following the procedure.
Perioperative bridge anticoagulation is recommended in patients with mechanical valves, atrial fibrillation, and/or those with prior VTE whom are at high risk for thromboembolism.
An assessment of risk vs. benefit should be used to decide whether to implement bridge anticoagulation in patients with an intermediate 5%-10%/year risk for recurrent VTE. This assessment should incorporate the procedural risk for perioperative bleeding.
No bridging anticoagulation is recommended in patients at low risk, less than 5% recurrent VTE risk annually.
Patients requiring minor dental procedures at moderate risk of bleeding whom are chronically treated with VKA may have the VKA continued through the perioperative period and be treated with prohemostatic agents for bleeding prevention; alternatively, VKA may be held 2-3 days prior to the procedure and resumed afterward.
Patients who are receiving VKA treatment should have this continued through the perioperative period for minor dermatologic procedures and cataract surgery.
Patients who receive bridging anticoagulation with intravenous unfractionated heparin should have the heparin stopped 4-6 hours prior to the procedure. Patients receiving subcutaneous low-molecular weight heparin should receive their last preoperative dose 24 hours prior to the procedure. For procedures with a high bleeding risk, demonstrated hemostasis, and a 48-72 hour interval should elapse prior to resuming low-molecular weight heparin; a 24-hour interval is reasonable for procedures at lower bleeding risk.
Patients who are receiving aspirin for secondary cardiovascular prevention should have aspirin continued through the perioperative period for minor dental procedures, minor dermatologic procedures, or cataract surgery.
If possible, it is recommended that surgery and procedures be deferred for at least 6 weeks following implantation of bare-metal coronary stents and for at least 6 months following implantation of drug-eluting coronary stents. If it is not possible to defer procedures, it is recommended that dual antiplatelet medications be continued through the perioperative period. These patients are expected to have increased perioperative bleeding and must be monitored closely.
Patients who are treated with aspirin and whom are at moderate or greater risk for cardiovascular events should have aspirin continued through the perioperative period to aid in reduction of perioperative CV risk.
Aspirin should be continued through the perioperative period in patients with coronary artery disease requiring CABG. Clopidogrel should be stopped 5 days preoperatively and aspirin should be continued in patients previously treated with dual antiplatelet therapy who require CABG.