Periprocedural anticoagulation

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

• bleeding risks associated with the procedure
• medications the patient is taking that alter coagulation or platelet function
• the patient's underlying thromboembolic risk

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

• the interventional radiologist who will be performing the procedure
• departmental or health service guidelines
• cardiology – if the patient has had previous PCI, mechanical cardiac valves or has high-risk atrial fibrillation
• hematologist – 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 physician's preferences.

Procedural bleeding risk

The risk and consequences of bleeding associated with a procedure can be grouped into three levels of risk:

Low risk

• PICC placement
• drainage catheter exchange
• central line removal
• IVC filter placement
• thoracocentesis or paracentesis 
• superficial aspiration or biopsy
• joint injection or aspiration
• thyroid biopsy 

Moderate risk

• facet joint block
• lumber puncture
• lung biopsy
• radiofrequency ablation
• epidural injection
• gastrostomy tube insertion
• liver biopsy
• uterine fibroid embolization
• chemoembolisation
• angiography
• venous interventions 
• intra-abdominal, thoracic wall or retroperitoneal abscess drainage

High risk

• TIPS procedure
• biliary interventions involving a new tract
• complex radiofrequency ablation
• renal biopsy
• nephrostomy placement

Procedural screening

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

• possible underlying coagulopathies (previously unexplained hemorrhage, renal disease, liver disease, hematological disease)
• to ensure adequate reversal once anticoagulants are stopped (only available for some anticoagulants)
• high risk - INR, aPTT, platelet count and hematocrit
• moderate risk - INR routinely recommended
• low risk - no testing is routinely recommended

Aims for coagulation parameters:

• low risk: INR <2.0, transfuse platelets if <50,000/μL
• moderate risk: INR <1.5, APTT <1.5 x control, transfuse platelets if <50,000/μL
• high risk: INR <1.5, APTT <1.5 x control, transfuse platelets if <50,000/μL

Antiplatelet therapy

Aspirin

• when to withhold: high risk procedures.
  • can generally be continued for low and moderate risk procedures
• how long to withhold: 5 days
• when to restart: 24 hours
• the only way to expedite the reversal of aspirin is with a platelet transfusion or desmopressin

ADP inhibitors (clopidogrel, ticagrelor, ticlopidine, prasugrel)

• when 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)
• how long to withhold: 5 days is usually sufficient. For high risk procedures it may be appropriate to withhold for 7 days
• prasugrel has a greater effect on platelet inhibition and should be withheld for 7 days
• when to restart:  24-48 hours depending on bleeding risk

NSAIDS

• how long to withhold: Generally only high risk procedures
• the 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
• when 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

• at 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

• warfarin 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
• how long to withhold:
  • for low bleeding risk withhold for 3-5 days aim INR <2.0
  • for moderate to high bleeding risk withhold for 5 days and aim for INR <1.5
• if an INR must be reversed faster then is would naturally drop by withholding warfarin – vitamin K, fresh frozen plasma or prothrombinax may be used
• when to restart: 12-24 hours
• as the patient level of anticoagulation will be subtheraputic for an extended period they may require bridging anticoagulation – see below

Directly acting oral anticoagulants (DOACs)

• when to withhold: moderate and high risk procedures
• the DOACs are renally-excreted and thus renal function is important to consider
• all can be restarted in 24-48 hours depending on the post procedural bleeding risk
• unlike warfarin, the DOACs act directly on the coagulation cascade and therefore patients reach therapeutic coagulation much more rapidly
• bridging 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
• there is no reliable way of monitoring reversal of anticoagulation with direct acting anticoagulants. A normal or slightly elevated aPTT (dabigatran) or antifactor Xa activity (rivaroxaban, apixaban) is reassuring. A patient's INR is not a reliable measure

Rivaroxaban (Xeralto)

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

Apixaban (Elquis)

• withhold 3-4 days
• if renal disease present >/= 5 days

Dabigatran (Pradaxa)

• withhold 4-5 days
• if renal disease present 6-7 days

Low molecular weight heparin

• administered subcutaneously at either prophylactic or therapeutic doses
• the activity can be measured using the anti-factor Xa assay. The aPTT is not a reliable measure if its effect
• prophylactic 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
• therapeutic 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)

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

Subcutaneous (prophylactic) 

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

Bridging anticoagulation

• the aim of bridging is to minimize the time someone is not anticoagulated periprocedurally
• bridging 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
• patients on NOACs generally do not require bridging as they have a rapid onset of anticoagulation
• bridging is usually achieved with a therapeutic dosing of LMWH or UFH but may be done at prophylactic doses or in-between depending on risk
• the patients who generally require bridging are:
  • this with mechanical heart valves
  • high risk atrial fibrilation – CHADS2 5-6
  • VTE within 3 months or severe thrombophilia
  • recent coronary artery stenting – seek cardiology opinion
• recent studies, including the BRIDGE trial and possibly the awaited PERIOP 2 trial have cast doubt on the efficacy of bridging anticoagulation