Anticoagulants

Perioperative management of anticoagulation requires balancing thrombo-embolic and haemorrhagic risk. In general:

Risk Stratification

Patients can be divided by:

  • Thrombotic risk
  • Bleeding (surgical) risk

Patients can then be stratified into:

  • Low thromboembolic and low bleeding risk
    Continue anticoagulation.
  • Low thromboembolic and high bleeding risk
    Withhold anticoagulation and antiplatelet agents (see below) without bridging.
  • High thromboembolic and high bleeding risk
    Withhold anticoagulation and antiplatelet agents, and consider bridging therapy.

Thrombotic Risk

↑ Thrombotic risk ↑ the importance of minimising the period without anticoagulation.

Divided into:

  • High risk
    ⩾10% annual CVA risk. Includes:
    • AF with:
      • Valvular AF
        AF secondary to valvular disease (either prosthetic, or related to rheumatic valvular disease) has a much higher stroke rate than non-valvular AF.
      • CHADS2 5-6 in non-valvular AF
      • TIA/ in last 3 months
    • Mechanical valves:
      • Any mechanical mitral valve
      • Old mechanical aortic valve
        Ball and cage, tilting disc.
    • VTE where:
      • VTE in last 3 months
        If VTE occurred in last month AND anticoagulation is contraindicated, consider an IVC filter.
      • Severe thrombophilia
      • Protein C/S or antithrombin deficiency
  • Intermediate risk
    4-10% annual CVA risk. Includes:
    • AF with CHADS2 3-4
    • Bileaflet mechanical aortic valve with any CVA risk factor
    • VTE where:
      • VTE in the last 3-12 months
      • Recurrent VTE
      • Active malignancy
  • Low risk
    ⩽4% annual risk. Includes:
    • CHADS2 0-2
    • Bileaflet mechanical aortic valve alone
    • VTE ⩾12 months ago

Bleeding Risk

Surgical risk of bleeding is classified into:

  • Low risk
    • Can be performed with an INR of ⩽1.5
    • Includes:
      • Dental surgery
        • Extraction of 1-3 teeth
        • Periodontal surgery
        • Abscess incision and draining
      • Ophthalmological surgery
        • Cataract surgery
        • Glaucoma intervention
      • Endoscopy without surgery (but with biopsy)
      • Superficial surgery
        e.g. Excision of skin lesions.
      • PPM/ICD insertion in absence of complex anatomy
      • EP study or simple ablations
      • Trans-radial endovascular/angiographic procedures
  • High risk
    • Neuraxial anaesthesia
    • Cardiac surgery
    • Thoracic surgery
    • Abdominal surgery
    • Major orthopaedic surgery
    • Liver biopsy
    • Renal biopsy
    • TURP

Management of Oral Anticoagulants

Drug When to cease for low bleeding risk surgery
Warfarin 5 days; check INR (see below)
Dabigatran Normal renal function: 24 hours
eGFR < 50mL/min: 48-72 hours
Rivaroxaban Normal renal function: 24 hours
eGFR < 50mL/min: 48 hours
Apixaban Normal renal function: 24 hours
eGFR < 50mL/min: 48 hours

Discuss with haematology if eGFR is < 30mL/min.

Management of Warfarin

For low risk of thromboembolism:

  • Check INR day prior to surgery
    • If INR 2-3; administer 3mg IV vitamin K
  • Check INR day of surgery
    • If INR < 1.5
      Surgery can proceed.
    • If INR > 1.5:
      • Defer surgery, or
      • Reverse warfarin with
        • Prothrombin factor concentrate (preferable)
        • FFP 10-15ml/kg.
  • Warfarin can recommence night after surgery at the previous maintenance dose
  • Thromboprophylaxis can be used until warfarin is therapeutic

For high risk of thromboembolism, two options exist:

  • Bridging
    Uses a short-acting anticoagulant (typically UFH or LMWH) to maintain therapeutic anticoagulation whilst longer acting drugs are withdrawn. Perform by:
    • Withhold warfarin 4-5 days prior to surgery
    • Monitor INR
    • When INR < 2.0
      Commence anticoagulation with:
      • LMWH
        1.5mg/kg daily or 1mg/kg BD.
      • UFH infusion
        Cease 4-6 hours prior to surgery.
  • Late reversal
    Appropriate when INR is stable in the preceeding 2-4 weeks.
    • Cease warfarin day prior to surgery
    • Administer 3mg IV vitamin K
    • Check INR day of surgery:
      • INR < 1.5
        Surgery can proceed.
      • INR > 1.5
        • Delay surgery
        • Reverse residual warfarin effect with prothrombinex or FFP

Bleeding risk with warfarin:

  • Bleeding risk is not elevated with an INR of ≤1.5
  • Bleeding risk is elevated with INR >2.0

Management of Novel Oral Anticoagulants

Note that NOACs:

  • Generally do not require bridging due to the shorter half-life
  • Can be restarted:
    • 6-8 hours post-operatively in the case of low bleeding risk and complete haemostasis achieved
    • 48-72 hours post-operatively in the case of high bleeding risk
      Can cconsider reduced dose on evening and first-postoperative day if bleeding and thrombosis risk are high.
  • For emergency surgery:
    • Cease NOAC
    • Deferring 12-24 hours since the last dose is ideal
      If not possible, discuss with surgeons, haematologist, and cardiology to plan management of bleeding.
    • Coagulation assays do not give a quantitative measurement of anticoagulation status, but can be used qualitatively
      Surgery can proceed if:
      • Dabigatran
        Normal APTT and TT, or normal APTT and mildly prolonged TT.
      • Rivaroxaban
        Normal PT.
      • Apixaban
        Normal Anti-Xa.

References

  1. Rahman A, Latona J. New oral anticoagulants and perioperative management of anticoagulant/antiplatelet agents. Aust Fam Physician. 2014;43(12):861-866. http://www.ncbi.nlm.nih.gov/pubmed/25705736. Accessed September 2, 2018.
  2. Tran HA, Chunital S, Tran H et al. An update of consensus guidelines for warfarin reversal. MJA 2013; 198:1-7.
  3. Tran H, Joseph J, Young L et al. New oral anticoagulants- a practical guide on prescription, laboratory testing and peri-procedural/bleeding management. Int Med J 2014; 44: 525- 536
  4. Tran H, Dooley M, Burke J, Dart T, Coutsouvelis J. Guideline: Alteration to Anticoagulant Therapy in Surgical Procedures. The Alfred Hospital, Melbourne. October 2016.
  5. Douketis JD, Spyropoulos AC, Duncan J, et al. Perioperative Management of Patients With Atrial Fibrillation Receiving a Direct Oral Anticoagulant. JAMA Internal Medicine. 2019;179(11):1469-1478. doi:10.1001/jamainternmed.2019.2431