Warfarin: Management at the time of elective surgery.

Objectives

Guidance on the management of Warfarin at the time of elective surgery

Warfarin: Before Surgery

Warfarin

Patients are prescribed long term warfarin to reduce the life time risk of stroke, transient ischaemic attack (TIA) or venous thrombo-embolism (VTE). The decision to stop warfarin before surgery and the timing of restarting afterwards reflects a balance between risk of surgical bleeding and the risk of a repeat event and some patients may wish to be involved in the decision.

For a patient prescribed warfarin after a recent stroke, TIA or VTE consider postponing elective surgery for three to six months (see next page).

Before surgery:

Can surgery proceed without stopping warfarin? (If not known, check with patient’s surgeon).

For example: some patients undergoing dental extraction, simple biopsy procedures or where the operation site is easily compressed.

If warfarin is to be stopped before surgery, the last dose should be taken on Day - 6 (where Day 0 is date of surgery).

Further management is guided by risk stratification, based on the indication for warfarin, see page 3.

Patients at increased risk of thrombosis may require peri-operative therapeutic anticoagulation (BRIDGING) with Low Molecular Weight Heparin (LMWH - dalteparin)

Patients at low risk of thrombosis may simply stop warfarin. The need for peri- operative prophylactic dalteparin is determined by the usual VTE risk assessment criteria.

Before surgery: Management of warfarin and low molecular weight heparin before and after surgery

	Increased risk of thrombosis	Decreased risk of thrombosis
Day -6	Take last dose of Warfarin	Take last dose of Warfarin
Day -5	No Warfarin	No Warfarin
Day -4	No Warfarin	No Warfarin
Day -3	If practicable check INR; if INR <2 commence therapeutic* dose dalteparin** [See note below]	No Warfarin
Day -2	Therapeutic* dose dalteparin**	No Warfarin
Day -1	If practicable check INR; if INR >1.5 consider Vitamin K. Prophylactic dose dalteparin**	No Warfarin
Day 0 = day of procedure	Check INR if not done on Day -1.	No warfarin

Warfarin: After Surgery

After surgery

Restart warfarin (at the patient’s usual maintenance dose) as soon as the risk of post operative bleeding is acceptable.
Patients at increased risk of thrombosis should receive therapeutic dalteparin, as soon as the risk of postoperative bleeding is acceptable, until INR is in the therapeutic range for that patient.
Do not start therapeutic dalteparin for at least 48 hours after surgery, because of the increased bleeding risk

The post-operative regime is suggested – gradually increasing dose of dalteparin.

Patients at low risk of thrombosis
Should continue prophylactic dalteparin until INR is in the therapeutic range for that patient. (If the oral route is not available by day +3 consider following the Increased Risk pathway)
INR should be checked daily from Day 2 of warfarin treatment

Warfarin: Risk stratification

Risk stratification

If none of the indications in the “increased risk / consider bridging” column apply the patient has a low risk of thrombosis and bridging is not necessary

Indication for warfarin

The patient is at INCREASED risk of thrombosis and bridging should be CONSIDERED if any of the following apply:

Venous thrombo- embolism (VTE)

Patient has had VTE in last three months.
Patient has previously had VTE whilst on therapeutic anticoagulation.
Patient has a target INR ≥ 3·5.Atrial Fibrillation

Patient has had stroke or TIA in last three months1.
Patient has had a previous stroke or TIA (at any time) and three or more of the following risk factors:

• Hypertension
• (>140/90mmHgoronmedication)
• Age>75years
• Diabetesmellitus
• SevereLVimpairment2

Mechanical Heart Valve

All patients with mechanical mitral valve.
All patients with mechanical aortic valve and any of:
• Atrialfibrillation
• StarrEdwards(Ball&Cage)prosthesis
• Severe LV impairment
• Stroke/TIA in last six months

Notes

If possible postpone elective surgery until at least three months after event.
If cardiac function has not been documented there is NO need to perform echocardiography to assess need for bridging UNLESS there is a clinical concern about congestive cardiac failure.
This type of valve was not implanted after 1993.
If possible postpone elective surgery until at least six months after event.

After surgery: Management of Warfarin and low molecular weight hepari

After surgery

(Day 1 = the first day after surgery, assuming haemostasis has been secured)

Day 1&2	Warfarin: at usual dose Dalteparin: prophylactic dose	Warfarin at usual dose Dalteparin: prophylactic dose
Day 3&4	Warfarin at usual dose. Dalteparin, either: twice daily prophylactic dose or start therapeutic* dose	Continue warfarin at usual dose Continue prophylactic dalteparin until INR is >2 If the oral route is not available by day +3 consider following the Increased Risk pathway Continue for Day 5 & 6
Day 5	Warfarin at usual dose. If not already done – start therapeutic* dalteparin
Day 6	Warfarin at usual dose. Continue therapeutic dalteparin until INR is >2
* 200 units / kg, max 18,000 units (may also be given twice daily - ie 100 units / kg bd, which may be more effective in patients at particularly high risk of thrombosis)	** Before 18:00h. Note re Day - 3: If INR check is not practicable and there is no suspicion of raised INR proceed with therapeutic dalteparin.

References

This guideline is based on the following publications:

David Keeling D, Campbell Tait R, Watson H, on behalf of the British Committee for Standards in Haematology. Peri-Operative Management of Anticoagulation and Antiplatelet Therapy. British Journal of Haematology 2016, 175, 602–613 http://onlinelibrary.wiley.com/doi/10.1111/bjh.14344/epdf
van Veen JJ, Makris M. Management of peri-operative anti- thrombotic therapy. Anaesthesia 2015, 70 (Suppl. 1), 58–67 http://onlinelibrary.wiley.com/doi/10.1111/anae.12900/pdf
Association of Anaesthetists of Great Britain and Ireland, Obstetric Anaesthetists’ Association and Regional Anaesthesia UK. Regional anaesthesia and patients with abnormalities of coagulation. Anaesthesia 2013; 68: 966-72 http://onlinelibrary.wiley.com/doi/10.1111/anae.12359/abstract
Practical management of patients who are receiving new oral anticoagulants.
Thrombosis Canada 2017