Peri-operative management of anticoagulation

Marc Carrier MD, MSc FRCPCAssistant Professor, University of OttawaAssociate Scientist, Ottawa Health Research Institute

Today

• Peri-operative bridging– Warfarin– ASA– Clopidogrel

• Post-operative Thromboprophylaxis– Orthopedic surgery– General surgery

Peri-op bridging(warfarin)

Dilemma:Pre and Post-op Risk assessment

Preventable thromboembolism

Major bleeds

Pharmacokinetics

• INR will normalise in a time period ranging from 50 to over 200 hours but 23% remain higher than 1.2 five days after d/c OACs

INR after warfarin induction

• When reinitiated a therapeutic level of anticoagulation will be achieved in a variable time period ranging from 2 to 10 days

• When OACs are discontinued and re-initiated the length of time with sub-therapeutic INRs is highly variable

• As a consequence clinicians need to consider “bridging therapy”

Assessment of Thrombosis Risk

• Venous Vs Arterial Thrombosis

Arterial Thrombosis – High riskCHADS2

Congestive Heart Failure

1

Hypertension 1

Age >70 1

Diabetes 1

Stroke/TIA 2

Total

0-2: 1.5-2.5%/yr stroke

> 2: 4.0-18.2%/yr stroke

Risk of Bleeding from Procedure

• Low Risk Procedure– Dental procedure

– Skin Biopsy

– Cataract surgery

– GI:

• Diagnostic colonoscopy or endoscopy

• EGD +/- biopsy• Flexible Sphincteromy+/- biopsy• Biliary/pancreatic stent

• ERCP without sphincterotomy

• Moderate or High risk

Bleeding risk→

Thrombosis Risk↓

Low High

Low

High Bridge

STOP

STOP

STOP

Bridging with LMWH

D -5 OR D5-10

Clinic

Home

Local lab

X

Summary(pre-op)

• Stop warfarin 5 days before surgery• Assess need for peri-operative bridging

• High risk: Therapeutic LMWH > IV UFH• Moderate risk: Therapeutic > prophylactic LMWH > IV UFH• Low risk: no bridging or prophylactic LMWH• If therapeutic LMWH is used:

– 50% therapeutic dose on OR day -1– No need to follow anti-Xa levels

• If prophylactic LMWH is used:– Last dose 24 hours before OR

• If IV UFH is used: Stop infusion 4 hours pre-op

• STAT INR 1-2 days before OR day• If INR > 1.5 give 1-2 mg of PO vitamin K

Summary(post-op)

• Resume VKA 12 to 24 hours post op• Good hemostasis

• PO intake

• Epidural is out

• Resuming Post-op LMWH bridging is • POD1 if good hemostasis

• If using therapeutic doses of LMWH/UFH» POD1 if minor surgical procedure» Consider resuming on POD2 if high bleeding risk major surgery» No need to follow anti-Xa

• D/C LMWH or UFH once INR therapeutic – i.e. > 2.0 or 2.5 depending on indication

Peri-op bridging(ASA, clopidogrel)

ASA/Clopidogrel

• If not high risk for cardiac events:– Stop 7 to 10 days before the procedure– Resume on POD1 (24 hours post-op)

• Adequate hemostasis

• If high risk of cardiac events (exclusive of coronary stents) for non-cardiac surgery

• Continue aspirin• Hold clopidogrel at least 5 days and preferable within 10 days of

surgery

• If high risk of cardiac events (exclusive of coronary stents) for CABG• Same as above• If ASA is interrupted then needs to be reinitiated between 6 and 48

hours after CABG

ASA/Clopidogrel

• Coronary stent• If bare metal coronary stent within 6 weeks

– Continue ASA and clopidogrel peri-operatively

• If drug-eluting stent within 12 months– Continue ASA and clopidogrel peri-operatively

• In patients with coronary stents who have interruption of ASA or clopidogrel

– No need to routinely bridge these patients

Prevention of Venous Thromboembolism

General Principles

• Should think about thromboprophylaxis for every patients• Mechanical methods alone in patients at high risk of

bleeding only!• May be used as an adjunct to anticoagulant

• The use of ASA alone as thromboprophylaxis is not recommended for any patient group!

What is the risk?

Risk factors for VTE

General Surgery

• Low-risk general surgery patients undergoing minor procedure• No need for thromboprophylaxis

• Early and frequent ambulation

• Moderate-risk general surgery patients who are undergoing a major procedure for benign disease

• LMWH, IFH sc TID or BID, or fondaparinux

• Higher-risk general surgery patients who are undergoing a major procedure for cancer

• LMWH, UFH sc TID or fondaparinux

• Continue thromboprophylaxis until discharge except:• Cancer patients: at least 7 to 10 days

• Cancer patients + other risk factors: up to 28 days

General Surgery

• Entirely laparoscopic surgery procedure with no additional thromboembolic risk factors

• No need for thromboprophylaxis• Early and frequent ambulation

• If additional VTE risk factors then thromboprophylaxis until D/C home (unless cancer)

Orthopedic Surgery

• LMWH– Prophylactic doses– Dalterapin 5000 IU OD, enoxaparin 40 mg OD or 30 mg bid,

tinzaparin 4500 IU OD– Starting on POD1

• Fondaparinux (2.5 mg started 6 to 24 hours post-op)• Warfarin

– target INR 2.0-3.0

• Rivaroxaban– 10 mg OD

• Dabigatran– 220 or 150 mg OD

• Not ASA, mechanical methods alone, dextran, or UFH

Duration

• THR, TKR or HFS:• At least 10 days

• THR, HFS:• Thromboprophylaxis should be extended beyond 10 days and

up to 35 days

• TKR: • Can consider extending thromboprophylaxis beyond 10 days

and up to 35 days

• Knee arthroscopy:• No need for thromboprophylaxis if no other VTE risk factors• If other risk factors, consider LMWH

Trauma

• Thromboprophylaxis if possible• LMWH alone• LMWH + mechanical methods• Hold LMWH if high risk of bleeding

– Don’t forget to resume…

• No screening U/S for DVT• No IVC filter insertion as thromboprophylaxis• Continue thromboprophylaxis until hospital D/C• If patient undergoes inpatients rehab:

• Switch to warfarin (target 2.0-3.0) until D/C home• Or continue LMWH prophylaxis

Thank You