Anticoagulants (Oral) – A General Overview



For further information on individual agents, please refer to specific monographs


  Risk of Thromboembolism


Perioperative anticoagulation decision-making should take into account the patient’s underlying thrombotic risk (see figure 1)1. Risk of thrombosis should be balanced against urgency of surgery; non-urgent surgery should be delayed where possible in acute situations where thrombosis risk will improve (e.g. patients with recent CVA or VTE). A Haematologist should be consulted for complex VTE patients.

* All DOACs are currently contraindicated for patients with a metallic heart valve
**AF, prior CVA / TIA, hypertension, diabetes mellitus, congestive cardiac failure, age > 75 years
*** Active cancer, antiphospholipid syndrome, deficiency of protein C, protein S, or Antithrombin, multiple thrombophilia
**** Heterozygous for Factor V Leiden or prothrombin gene mutation

Figure 1 – Thromboembolic Risk Stratification


  Risk of Bleeding 

 

Figure 2 below outlines the bleeding risk of common procedures including those where anticoagulation therapy may not have to be interrupted. This is intended as a guide rather than a comprehensive list of the bleeding risk for all operations. The operating surgeon best defines the exact bleeding risk of the procedure and, if necessary, should be consulted to confirm the need for anticoagulant interruption.

Figure 2 – Bleeding Risk associated with Common Procedures1 

*It is often possible to perform low bleeding risk procedures without interrupting anticoagulation therapy – this will be dependent on the INR for warfarin and ensuring prudent timing of the procedure in relation to DOAC administration time (see individual monographs for further advice)


  Bridging Therapy with Low Molecular Weight Heparin (LMWH)


DOACs
Bridging with therapeutic LMWH is not required for patients on a DOAC. The predictable pharmacokinetics of DOACs allows for properly timed short-term cessation of DOAC therapy prior to surgery. In addition, bridging with heparin / LMWH is associated with an increased bleeding risk without reducing cardiovascular events1.

Use of prophylactic doses of LMWH may be considered post-operatively if the patient is unable to recommence the DOAC within 24 hours of surgery due to the potential risk of bleeding associated with the surgery / procedure or inability to take oral therapy. Commencement of prophylactic doses of LMWH should be based on the patient’s thromboembolic risk versus the associated bleeding risk (as detailed above). LMWH should never be administered in conjunction with DOAC therapy.

Warfarin
Bridging with therapeutic LMWH may be required for patients on warfarin. The decision to use bridging therapy should be based on the patient’s thromboembolic risk and the associated bleeding risk (as detailed above) – see Warfarin monograph for details of the British Committee for Standards in Haematology’s recommendations.

Use of prophylactic doses of LWMH should be considered if the patient is unable to recommence warfarin in the immediate post-operative period (e.g. due to concerns around post-operative bleeding or oral absorption).

In some cases, patients may require post-operative bridging therapy with therapeutic LMWH until they are able to safely recommence their warfarin.


  References

  1. Steffel J, Verhamme P, Potpara TS et al. European Society of Cardiology. The 2018 European Heart Rhythm Association Practical Guide on the use of non-vitamin K antagonist oral anticoagulants in patients with atrial fibrillation. European Heart Journal. 2018; 39:1330-1393