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CEASING ORAL ANTICOAGULANTS BEFORE SURGERY

A guide for patients by Malcolm Barlow
(Medical Practitioners click here)

Some of what follows, particularly the charts and tables are taken from the NSW Clinical Excellence Commission Guidelines on Perioperative Management of Anticoagulant and Antiplatelet Agents, 2018. This detailed document is intended as a reference for medical practitioners.

 

There are 5 oral anticoagulants (OACs) available in this country – warfarin, phenindione, dabigatran, rivaroxaban and apixaban. Apixaban, dabigatran and rivaroxaban will collectively be referred to as NOACs (novel oral anticoagulants) in this article. Aspirin, clopidogrel, ticagrelor, prasugrel and others are not anticoagulants, they are anti-platelet drugs. You may also be asked to stop these anti-platelet drugs. This will need to be discussed with the doctor who prescribed these medications, and depends on the original indication for the drug. This guide does not deal with the anti-platelet drugs.

The appropriate time to cease your OAC depends on several factors – which OAC you are taking, your kidney function, the type of surgical procedure (which determines the risk and consequences of bleeding), and your risk of clot formation.

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The best person to determine the risk of bleeding from the procedure is the one performing the procedure. Various procedures (in this article the terms "procedure" and "surgery" mean the same) can be classed as having minimal risk, low risk, or high risk of bleeding. Examples of typical procedures that would usually fit into each class are given below in the table, however the proceduralist/surgeon is ultimately the one who decides the risk and consequences of bleeding for your procedure.

Minimal Risk of Bleeding

  • Minor skin procedures - excisions of small leasions and small skin cancers

  • Cataract procedures

  • Minor dental work - extractions, prosthetics, cleaning, fillings

  • Electrophysiology procedures (venous access only)

  • Pacemaker or defibrillator (ICD) generator change

  • ILR insertion

Low Risk of Bleeding
(2 day risk of major bleed < 2%)

  • GI endoscopy and bronchoscopy +/- biopsy

  • Shoulder/foot/hand surgery

  • Arthroscopy

  • Coronary angiography/stent

  • Electrophysiology procedures (arterial access)

  • Pacemaker or ICD insertion

  • Laparoscopic cholecystectomy

  • Abdominal hysterectomy

  • Abdominal hernia repair

High Risk of Bleeding
(2 day risk of major bleed ≥ 2%)

  • Major surgery with extensive injury

  • Cancer surgery

  • Major orthopaedic surgery

  • Reconstructive plastic surgery

  • Urologic or intra-abdominal surgery

  • Deep organ biopsy

  • Cardiac, intracranial or spinal surgery

  • Any other major operation (duration > 45 min)

Clot formation with or without dislodgement (thromboembolism) is potentially serious as it can lead to stroke, blockage of blood flow to another vital organ or limb, blockage of a mechanical heart valve, deep vein thrombosis, or a clot travelling to your lungs. The best person to determine your risk of forming clots is the doctor who knows most about you, usually your GP. If you are one of my patients that I see regularly, I am usually comfortable to also make this determination. A table summarising thromboembolism risk based on whether you take an anticoagulant because of a mechanical heart valve, atrial fibrillation, or venous thromboembolism is provided at the end of this document. This table is a guide only - your treating doctor is still best placed to assess your risk.

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In general, procedures that carry minimal risk of bleeding do not require cessation of OAC, although you still may be asked to avoid taking the OAC on the day of the procedure. For procedures that carry a higher risk of bleeding there are two approaches to withholding OACs:

  • 1) Withhold the OAC without using bridging anticoagulation – the OAC is stopped before the procedure and no other anticoagulation is given. This is appropriate for those with low-moderate risk of thromboembolism taking warfarin. This is also appropriate for those with any risk of thromboembolism taking NOACs.

  • 2) Withhold the OAC with use of bridging anticoagulation – an injectable anticoagulant is used in place of the oral anticoagulant. This is appropriate for those taking warfarin with a high risk of thromboembolism. Bridging anticoagulation allows time for the oral anticoagulant to wash out of your system completely before surgery. The bridging anticoagulant is usually withheld 24 hrs prior to surgery. Therefore, there is still a time when you will not be receiving any anticoagulant, but this time is minimized with the bridging approach.

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As mentioned already, the best person to judge which of these approaches is preferrable is the doctor who knows most about you, usually your GP. The proceduralist may not be the best person to decide which approach, as they may not know all your medical history.

Stopping anticoagulants with and without bridging anticoagulation

Warfarin and Phenindione - vitamin K antagonists

Warfarin (or phenindione) is the anticoagulant of choice for mechanical heart valves, severe thrombophilic conditions and in those with compromised kidney function. It takes a few days for the effect of these drugs to disappear. Surgery is generally safe once the INR falls below 1.5, and ideally the INR should be checked either on the day of, or the day before surgery. Examples are shown below.

Without bridging anticoagulation
Warfarin ceasing

Clinical Excellence Commission, 2018, Guidelines on Perioperative Management of Anticoagulant and Antiplatelet Agents

With bridging anticoagulation
Warfarin ceasing with bridging

Generally your surgeon or the hospital will give you the prescription for the bridging anticoagulant. This is a subcutaneous injection taken once or twice daily.

Clinical Excellence Commission, 2018, Guidelines on Perioperative Management of Anticoagulant and Antiplatelet Agents

Apixaban, Dabigatran and Rivaroxaban - direct thrombin inhibitor and factor Xa inhibitors

Bridging therapy is generally not required when ceasing these drugs, as their effect disappears more quickly than with warfarin, and is similar to the time taken for the effect of the usual bridging anticoagulant agent to disappear. Consequently, the period of time you are exposed to loss of anticoagulation is only brief. The time taken for the anticoagulant effect to disappear after stopping one of these drugs is heavily dependent on your kidney function (your GP will know this), see table.

Timing of the last dose of NOAC before surgery
Ceasing NOACs

Note that, unlike with warfarin, it is not necessary to stop these drugs 5 days prior to surgery. I do not advocate ceasing the drug any sooner than what is recommended in these tables, as doing so unnecessarily exposes you to a higher risk of thromboembolism, without reducing any further your risk of bleeding during surgery.

 

It is important to understand that while there is an increased risk of clot formation once your OAC is ceased, there is also a risk of bleeding (potentially serious bleeding depending on the procedure) when having a procedure/operation. We have to balance these competing risks when making a decision to stop the OAC. Either way, during this time you are exposed to a higher risk of bleeding and/or clot formation and some people will experience these complications, especially those at the highest risk. In this situation, you will have to decide whether the risks justify having the surgery. You should have this discussion with the person recommending the procedure or surgery.

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APPENDICES

Thromboembolism Risk Categories

Mechanical Heart Valve

Atrial fibrillation (AF) or flutter

Venous thromboembolism (VTE)

Bileaflet aortic valve - and one or more stroke risk factors:

  • AF, prior stroke/TIA

  • Hypertension

  • Diabetes

  • Congestive Heart Failure

  • Age > 75 years

CHADS2 score 3-4

  • VTE - 3-12 months ago

  • Non-severe thrombophilia (e.g. heterozygous favtor V Leiden mutation)

  • Recurrent VTE

  • Active cancer

Moderate Risk of Thromboembolism

High Risk of Thromboembolism

  • Mitral valve prosthesis

  • Any caged-ball or tilting disc prosthesis

  • Recent stroke/TIA - within 6 months believed related to the mechanical valve

  • CHADS2 score 5-6

  • Recent stroke/TIA - within 3 months believed due to AF

  • Rheumatic valve disease

  • Recent VTE - within 3 months

  • Severe thrombophilia (e.g. protein C, protein S, or antithrombin III deficiency; antiphospholipid antibodies)

Low Risk of Thromboembolism

Bileaflet aortic valve - without AF or other stroke risk factors

CHADS2 score 0-2 - and no prior stroke/TIA

VTE - > 12 months ago and no other risk factors

Clinical Excellence Commission, 2018, Guidelines on Perioperative Management of Anticoagulant and Antiplatelet Agents

CHADS2 Score

  • Congestive heart failure

  • Hypertension history

  • Age ≥ 75 years

  • Diabetes

  • Prior stroke or TIA

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Pharmacokinetics of the NOACs
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