Periprocedural anticoagulation

Introduction

When planning an interventional procedure a patient’s coagulation status must be assessed and optimised to best balance the risk of bleeding and thrombosis. The following must be considered;

• Bleedingbleeding risks associated with the procedure
• Medicationsmedications the patient is taking that alter coagulation or platelet function
• Thethe patients underlying thromboembolic risk

When deciding how to best manage periprocedural coagulation it is important to first consult; 

• Thethe interventional radiologist who will be performing the procedure
• Departmentaldepartmental or health service guidelines
• Cardiologycardiology – if the patient has had previous PCI, mechanical cardiac valves or has high-risk atrial fibrillation
• Haematologisthaematologist – advice with specific thrombophilias, coagulopathies or regarding the reversal of anticoagulants

This article should act as a general guide and not supersede department guidelines or treating or physician preference.

Procedural bleeding risk

The risk and consequences of bleeding associated with a procedure can be grouped into 3 levels of risk. 

Low risk

• PICC placement
• Drainagedrainage catheter exchange
• Centralcentral line removal
• IVC filter placement
• Thoracocentesisthoracocentesis or paracentesis 
• Superficialsuperficial aspiration or biopsy
• Jointjoint injection or aspiration
• Thyroidthyroid biopsy 

Moderate risk

• Facetfacet joint block
• Lumberlumber puncture
• Lunglung biopsy
• Radiofrequencyradiofrequency ablation
• Epiduralepidural injection
• Gastrostomygastrostomy tube insertion
• Liverliver biopsy
• Uterineuterine fibroid embolisation
• Chemoembolisationchemoembolisation
• Angiographyangiography
• Venousvenous interventions 
• Intraintra-abdominal, thoracic wall or retroperitoneal abscess drainage

High risk

• TIPS procedure
• Biliarybiliary interventions involving a new tract
• Complexcomplex radiofrequency ablation
• Renalrenal biopsy
• Nephrostomynephrostomy placement

Procedural screening

Coagulation screening may be useful in selective cases in recognising and correcting underlying abnormalities. When to perform preprocedural coagulation screening:

• Possiblepossible underlying coagulopathies. (previously unexplained haemorrhage, renal disease, liver disease, haematological disease)
• Toto ensure adequate reversal once anticoagulants are ceased (only available for some anticoagulants)
• Highhigh risk – INR, aPTT, platelet count and haematocrit
• Moderatemoderate risk -  INR routinely recommended
• Lowlow risk – no testing is routinely recommended

Aims for coagulation parameters:

• Lowlow risk: INR <2.0, transfuse platelets if <50,000/MicroL
• Moderatemoderate risk: INR <1.5, APTT < 1.5 x control, transfuse platelets if <50,000/MicroL
• Highhigh risk: INR <1.5, APTT < 1.5 x control, transfuse platelets if <50,000/MicroL

Antiplatelet therapy

Aspirin

• Whenwhen to withhold: Highhigh risk procedures. Can generally be continued for low and moderate risk procedures
• Howhow long to withhold: 5 days
• Whenwhen to restart: 24 hours
• Thethe only way to expedite the reversal of aspirin is with a platelet transfusion or desmopressin

ADP inhibitors (clopidogrel, ticagrelor, ticlopidine, prasugrel)

• Whenwhen to withhold: For low, moderate and high risk procedures. Some may choose to continue for low risk procedures, especially if high risk associated with stopping (i.e. drug eluding stent)
• Howhow long to withhold: 5 days is usually sufficient. With high risk procedures it may be appropriate to withhold for 7 days
• Prasugrelprasugrel has a greater effect on platelet inhibition and should be withheld for 7 days
• Whenwhen to restart:  24 – 48 hours depending on bleeding risk

NSAIDS

• Howhow long to withhold: Generally only high risk procedures
• Thethe time these must be withheld depends on the half-life of the agents
  • Short half-life NSAIDS (eg diclofenac, ibuprofen and meloxicam) for 24 hours
  • Medium half-life NSAIDS (eg naproxen, celecoxib) for 2-3 days
  • Long half-life NSAIDS (eg meloxicam) for 10 days
• Whenwhen to restart: 24 hours

Cardiac stents and withholding antiplatelet therapy

Ceasing antiplatelet therapy in patients who have underwent cardiac percutaneous intervention can increase the risk of stent thrombosis. The most important factors to consider are the type of stent used and the time since PCI.

If possible do not interrupt dual antiplatelet for

• Atat least 6 weeks, and ideally 3 months, following bare metal stenting
• 6-12 months following the placement of a drug eluding stent

It is always useful seek cardiology opinion when considering temporary cessation of antiplatelet therapy in these patients. 

Anticoagulant therapy

Warfarin

• Warfarinwarfarin is a vitamin k antagonist that has reduced in use since the addition of DOACS, but is still used in patients with prosthetic mechanical valves, venous thromboembolic disease and atrial fibrillation
• Howhow long to withhold:
  • Forfor low bleeding risk withhold for 3-5 days aim INR <2.0
  • Forfor moderate to high bleeding risk withhold for 5 days and aim for INR <1.5
• Ifif an INR must be reversed faster then is would naturally drop by withholding warfarin – vitamin k, fresh frozen plasma or prothrombinax may be used
• Whenwhen to restart: 12-24 hours
• Asas the patient level of anticoagulation will be subtheraputic for an extended period they may require bridging anticoagulation – see below

Directly acting oral anticoagulants (DOACs)

• Whenwhen to withhold: moderate and high risk procedures
• Thethe DOACs are renally excreted and thus renal function is important to consider
• Allall can be restarted in 24-48 hours depending on the post procedural bleeding risk
• Unlikeunlike warfarin, the DOACs act directly on the coagulation cascade and therefore patients reach therapeutic coagulation much more rapidly
• Bridgingbridging is almost never required with these medications. The only situations where it could be of benefit is in high thromboembolic risk scenarios in patients unable to take oral medications
• Therethere is no reliable way of monitoring reversal of anticoagulation with direct acting anticoagulants. A normal or slightly elevated aPTT (dabigatran) or anti factor Xa activity (rivaroxaban, apixaban) is reassuring. A patients INR is not a reliable measure

Rivaroxaban (Xeralto)

• Withholdwithhold for 3-4 days
• 5 days in CKD stage 3
• 7 days in CKD stage 4

Apixaban (Elquis)

• Withholdwithhold 3-4 days
• Ifif renal disease present >/= 5 days

Dabigatran (Pradaxa)

• Withholdwithhold 4-5 days
• Ifif renal disease present 6-7 days

Low molecular weight heparin

• Administeredadministered subcutaneously at either prophylactic or therapeutic doses
• Thethe activity can be measured using the anti-factor Xa assay. The aPTT is not a reliable measure if its effect
• Prophylacticprophylactic dose: Low-risk procedures do not require ceasing. Moderate to high-risk procedures require withholding from 12-24 hours and 24 hours until the LMWH is restarted
• Therapeutictherapeutic dose: Low-risk procedures require 12-24 hours withholding and restarting at 6 hours. Moderate to high-risk procedures require withholding for 24 hours and recommencing at 24-48 hours

Unfractionated heparin

Intravenous (therapeutic)

• Whenwhen to withhold: low, moderate and high-risk procedures
• Timetime to withhold: 4 hours
• Thethe reversal can be measured with the patients aPTT. Aim for <1.5 x control
• Rapidrapid reversal of heparin is achievable with IV protamine
• Whenwhen to restart: 6-48 hours depending on bleeding risk

Subcutaneous (prophylactic) 

• Thisthis is usually administered subcutaneously as a prophylactic anticoagulant (5000U every 8-12 hour)
• Whenwhen to withhold: moderate and high risk procedures
• Timetime to withhold: 12-24 hours
• Whenwhen to restart: 24 hours 

Bridging anticoagulation

• Thethe aim of bridging is to minimise the time someone is not anticoagulated periprocedurally
• Bridgingbridging therapy is sometimes warranted in patients taking warfarin, due to slow reversal and anticoagulation. It is generally commenced once the INR is below the therapeutic level (2-3 days after ceasing) and stopped once the INR returns to a therapeutic level
• Patientspatients on NOACs generally do not require bridging as they have a rapid onset of anticoagulation
• Bridgingbridging is usually achieved with a therapeutic dosing of LMWH or UFH but may be done at prophylactic doses or in-between depending on risk
• Thethe patients who generally require bridging are:
  • Thisthis with mechanical heart valves
  • Highhigh risk atrial fibrilation – CHADS2 5-6
  • VTE within 3 months or severe thrombophilia
  • Recentrecent coronary artery stenting – seek cardiology opinion
• Recentrecent studies, including the BRIDGE trial and possibly the awaited PERIOP 2 trial have cast doubt on the efficacy of bridging anticoagulation