Makindo Medical Notes.com

General Principles

• To eliminate the effect of antithrombotic therapy before surgery, treatment should be stopped before surgery (~5 days for Warfarin, 7-10 days for antiplatelet drug) to minimizing bleeding risk
• Giving bridging after surgery increases the risk for bleeding; this risk depends on anticoagulant dose (therapeutic-dose > low-dose) and proximity to surgery (higher risk if given closer to surgery)
• Delaying resumption of therapeutic-dose bridging (for 48-72 h after surgery), decreasing the dose or avoiding its use after surgery can mitigate the risk for bleeding
• Low-dose LMWH/UFH is effective to prevent postoperative VTE, but the evidence is lacking that such regimens effective to prevent ATE

In resuming treatment after surgery, it takes:

• 2-3 days for the anticoagulant effect to begin after starting Warfarin
• 3-5 h for peak anticoagulant effect after starting LMWH - minutes for an antiplatelet effect to begin after starting ASA
• 3-7 days for peak inhibition of platelet aggregation after starting a maintenance dose of Clopidogrel
• Most surgery/procedures done out-of-hospital and potential thromboembolic or bleeding complications occur during the initial 2 wks after surgery while the patient is at home. Close patient follow-up during the early postop period allows early detection and treatment of complications

Risk stratifying - Valves

• The thrombotic risk in those with metallic heart valves depends on the site and type of valve. Small observational studies show that metallic aortic valves have a small risk of thrombotic events during perioperative interruption of anticoagulation even in the absence of bridging Heparin. The risk is much higher for metallic mitral valves. Evidence is mainly of older style valves and more modern valves may be associated with a much lower risk of thrombotic events. Furthermore poor cardiac function is associated with a higher risk of valve-related thrombotic events. As a general rule metallic mitral valves should be considered high thrombotic risk and receive bridging Heparin, metallic aortic valves may be considered slightly lower risk but still require discussion with their cardiologist. Because of the individual nature of thrombotic risk perioperative management of patients with prosthetic cardiac valves should also be discussed with the patient cardiologist prior to surgery (not forgetting that certain cases will need prophylactic peri-operative antibiotics as well).
• High Risk: Any mitral valve prosthesis Older (caged-ball or tilting disc) aortic valve prosthesis Recent (within 6 months) stroke or TIA
• Moderate Risk: Bileaflet aortic valve and at least one of: Atrial fibrillation, prior stroke or transient ischaemic attack, hypertension, diabetes, congestive heart failure, age >75 years
• Low Risk: Bileaflet aortic valve without atrial fibrillation and no other risk factors for stroke

Risk stratifying AF

• High Risk: CHADS2 score = 5-6. Recent (within 3 months) stroke or TIA or Rheumatic valvular heart disease. Consider Heparin bridging in AF if the CHADS score > 4 However, it is likely to be much higher (15%/month) during the first month after an arterial embolism of cardiac origin and these patients should be considered to be at high thrombotic risk and management discussed with a consultant cardiologist.
• For patients with AF on antiplatelet therapy rather than Warfarin a similar risk assessment should be performed. Those at high risk should be discussed with their cardiologist or stroke physician; a decision with regards to continuing or stopping Warfarin or antiplatelet therapy in low-risk cases depends on the type of drug and bleeding risk of the surgery intended.
• Moderate Risk: CHADS2 score = 3-4
• Low Risk: CHADS2 score = 0-2 and no prior stroke or TIA N.B. Individual patient characteristics (e.g. prior embolic stroke or perioperative stroke/TIA) may override suggested risk stratification

Risk stratifying VTE

• High Risk: Recent VTE (<3 months ago) Severe thrombophilia (e.g. antiphospholipid antibodies). Interruption of anticoagulation during the first month following VTE is associated with an extremely high rate of recurrence. Assuming 4 or 5 days of subtherapeutic anticoagulation peri-surgery this risk is estimated to be in the region of 70 % which falls to around 13% during months 2 and 3 post-VTE after which it is around 1.5%/year. If at all possible surgery should be avoided during this period and if unavoidable Heparin should be used to bridge the period of suboptimal anticoagulation and management discussed with a consultant haematologist. Patients within one month of proximal DVT should be considered for an IVC filter to cover the perioperative period. After the third month the risk of a further thrombotic event is much lower. Patients on long term Warfarin for recurrent VTE are at higher risk (up to 15%/year(1)).
• Moderate Risk: VTE within the past 3-12 months Non severe thrombophilia (e.g. heterozygous factor V mutation) Recurrent VTE Active cancer (treated within 6 months or palliative)
• Low Risk: Prior VTE >12 months ago and no other risk factors

Risk Stratifying IHD

• Elective surgery should be delayed at least 1-month post MI. Any ACS should have been investigated and optimised prior to elective surgery. Discuss with a cardiologist if need to operate before this.
• Clopidogrel should be continued for a minimum of 4-6 weeks post-insertion of a bare metal coronary stent as there is a high risk of stent thrombosis (and to a lesser extent up to 3 months).
• Clopidogrel should be continued for a minimum of 3-6 months post drug-eluting coronary stent insertion (depending on type of stent) though it is preferable to continue for up to a year.
• Aspirin post coronary stent should preferably not be stopped at all (at least for a minimum of 15 months unless there is a very high bleeding risk from the surgery.
• A history of heart failure with an ejection fraction <35% or severe aortic stenosis are also recognised as high peri-operative cardiac risk factors

High bleeding-risk surgeries/procedures include:

• Urologic surgery/procedures: TURP, bladder resection or tumour ablation, nephrectomy or kidney biopsy (untreated tissue damage after TURP and endogenous urokinase release)
• Pacemaker or ICD implantation (separation of infraclavicular fascia and no suturing of unopposed tissues may lead to hematoma)
• Colonic polyp resection, especially >1-2 cm sessile polyps (bleeding occurs at transected stalk after haemostatic plug release)
• Vascular organ surgery: thyroid, liver, spleen
• Bowel resection (bleeding may occur at anastomosis site)
• Major surgery involving considerable tissue injury: cancer surgery, joint arthroplasty, reconstructive plastic surgery
• Cardiac, intracranial or spinal surgery (small bleeds can have serious clinical consequences)

Patients requiring Minor Procedures

• Recommendation: In patients who require minor dental surgery and are receiving VKA therapy, we suggest either continuing VKA with co-administration of an oral pro haemostatic agent or stopping VKAs 2-3 days before the procedure instead of alternative strategies (Grade 2C).
• Recommendation: In patients who require minor skin procedures and are receiving VKA therapy, we suggest continuing VKAs around the time of the procedure and optimizing local haemostasis instead of other strategies (Grade 2C).
• Recommendation: In patients who require cataract surgery and are receiving VKA therapy, we suggest continuing VKAs around the time of the surgery instead of other strategies (Grade 2C).

High risk patients high risk procedures

• Recommendation: In patients who require temporary interruption of a VKA before surgery, we recommend stopping VKAs approximately 5 days before surgery instead of stopping VKAs a shorter time before surgery (Grade 1C).
• Recommendation: In patients who require temporary interruption of a VKA before surgery, we recommend resuming VKAs approximately 12-24 hrs after surgery (evening of or next morning) and when there is adequate haemostasis instead of later resumption of VKAs (Grade 2C).
• Recommendation: In patients with a mechanical heart valve, atrial fibrillation or VTE at high risk for TE, we suggest bridging anticoagulation instead of no bridging during interruption of VKA therapy (Grade 2C).

Bridging therapies and High thrombotic risk

• The risk of serious haemorrhage for patients therapeutically anticoagulated with unfractionated Heparin perioperatively is estimated to be in the region of 3%. The risk depends on the procedure performed and can be mitigated by delaying re-anticoagulation after the procedure and reducing the anticoagulation. It's a balance of haemorrhage vs thrombotic risk. In most, the haemorrhagic risk will exceed any thrombotic risk.
• Those at high thrombotic risk should be considered for bridging therapy with specialist assessment and LMWH is preferred to intravenous unfractionated Heparin (UFH) as it gives more consistent anticoagulation and does not require APTT monitoring or IV access and can be self-administered on an outpatient basis if needed. Its efficacy is well documented.
• Warfarin restarted at a maintenance dose can be commenced once haemostasis has been achieved. UFH/LMWH should be stopped once the INR is therapeutic.

Bridging therapies and Low thrombotic risk

• Anticoagulation is stopped and those who have a low thrombotic risk should receive prophylactic dose LMWH whilst an inpatient.
• Restart Warfarin maintenance dose (not reloading) once haemostasis has been achieved. UFH/LMWH should be stopped once the INR is therapeutic.

Those on oral anticoagulation and antiplatelet agents

• In these patients the risk of bleeding should be assumed to be greater than in those treated with oral anticoagulation alone. Seek specialist advice prior to stopping drugs.

Dabigatran

• >50 mL/min: Standard Bleeding Risk Stop dabigatran 1 to 2 days before surgical procedure. High Bleeding risk stop dabigatran 2 to 4 days before surgical procedure
• < 50 mL/min: Standard Bleeding Risk Stop dabigatran 3 to 5 days before surgical procedure. High Bleeding Risk Stop dabigatran > 5 days before surgical procedure
• Minor surgery or procedure with low bleed ing risk: restart 12-24 hours
• Major surgery or high bleed risk surgery or procedure: Start 48 to 72 hours if approved by the surgeon

Rivaroxaban

• >30 mL/min: Standard Bleeding Risk Stop Rivaroxaban 24 hours before surgical procedure. High Bleeding risk stop Rivaroxaban 48 hours before surgical procedure
• < 30 mL/min: Standard Bleeding Risk Stop Rivaroxaban 48 hours before surgical procedure. High Bleeding Risk Stop Rivaroxaban > 72 hours days before surgical procedure
• Minor surgery or procedure with low bleeding risk: restart 12-24 hours
• Major surgery or high bleed risk surgery or procedure: Start 48 to 72 hours if approved by the surgeon

Apixaban

• Serum creatinine < 1.5 mg/dl: Standard Bleeding Risk Stop Apixaban 24 hours before surgical procedure. High Bleeding risk stop Apixaban 48 hours before surgical procedure
• Serum Creatinine >= 1.5 mg/dl: Standard Bleeding Risk Stop Apixaban 48 hours before surgical procedure. High Bleeding Risk Stop Apixaban > 72 hours days before surgical procedure
• Minor surgery or procedure with low bleeding risk: restart 12-24 hours
• Major surgery or high bleed risk surgery or procedure: Start 48 to 72 hours if approved by the surgeon

Aspirin

• Moderate to High Cardiac Risk: Continue Aspirin around the time of surgery
• Low Cardiac Risk: Stop 7-10 days before surgery

Current Warfarin Perioperative guideliens

• Pre-operative bridging carries a low risk of bleeding but the use of post-operative bridging requires careful consideration due to the high risk of bleeding. We recommend that post-operative bridging should not be started until at least 48 h after high bleeding risk surgery
• Patients with VTE more than 3 months earlier can be given prophylactic dose LMWH (or a suitable alternative) rather than bridging therapy
• Patients with low-risk AF(no prior stroke or TIA)do not require bridging therapy
• Patients with a bileaflet aortic MHV with no other risk factors do not require bridging
• Patients with a VTE within the previous 3 months, patients with AF and previous stroke or TIA or multiple other risk factors, and patients with a mitral MHV should be considered for bridging therapy

References

• TRUST GUIDELINE FOR THE MANAGEMENT OF ADULT PATIENTS WHO REQUIRE ELECTIVE SURGERY OR AN INVASIVE PROCEDURE WHILST THEY ARE ANTICOAGULATED WITH Warfarin OR ON ANTIPLATELET THERAPY. Brighton and Sussex County.
• Periprocedural Anticoagulation - Adult - Inpatient and Ambulatory-Clinical Practice Guideline
• Guidelines on oral anticoagulation with Warfarin. British Committee for Standards in Haematology 2011