1 OXFORD HAEMOPHILIA AND THROMBOSIS CENTRE PROTOCOLS FOR OUT- PATIENT ORAL ANTICOAGULATION WITH VITAMIN K ANTAGONISTS DO NOT PRINT This is a controlled document. It becomes uncontrolled once printed or copied. It is important that the most current version is used It is available at http://ouh.oxnet.nhs.uk/anticoagulation Prepared by D. Keeling with input and review from S. Shapiro, N. Curry, V. Price, and L. Mulholland. AC Protocols version 4.1 May 2017 2 Contents Indications and target INR 3 Atrial fibrillation and cardioversion 3 Heart valve prostheses 4 Duration of treatment in venous thromboembolism 5 Commencement of oral anticoagulant therapy 5 Standard induction regimen commenced with heparin cover 5 Slow induction of anticoagulation in patients with atrial fibrillation 6 without heparin cover Management of anticoagulation in the peri-operative period for major surgery 7 or procedure where the INR has to be ≤1.3 Endoscopy 8 Dentistry 9 Management of bleeding and high INR in the absence of bleeding 10 Major bleeding 10 Non-major bleeding 10 High INRs in non-bleeding patients 10 Management of sub-therapeutic anticoagulation 11 Warfarin and antiplatelet medication 11 Point of care devices 12 Swapping to/from other oral vitamin K antagonists 13 References 14 AC Protocols version 4.1 May 2017 3 Indications and target INR This guideline refers to target INRs rather than target ranges though the target range is generally taken to be within 0.5 of the target, i.e. a target INR 2.5 equates to a target range of 2.0 to 3.0. Specifying tighter target ranges for fully anticoagulated patients e.g. 2.0 – 2.5 or 3.5 – 4.0 does not achieve tighter anticoagulation control but results in more blood tests and worse INR control (Meier, et al 2007). The most common target INR is 2.5. Others are: Recurrent VTE (DVT or PE) despite adequate anticoagulation 3.5 Cardioversion Pre - 3.0 Post - 2.5 Mechanical Heart Valves See below Warfarin is not usually indicated for ischaemic stroke without atrial fibrillation (except in antiphospholipid syndrome), retinal vessel occlusion, peripheral artery thrombosis, coronary artery graft or coronary angioplasty and stents. Atrial fibrillation Anticoagulation is normally offered to patients with a CHADSVASc score ≥ 2 and considered in men with a CHADSVASc score of 1 (NICE 2014). Condition Points C Congestive heart failure 1 H Hypertension (or treated hypertension) 1 A2 Age >75 years 2 D Diabetes 1 S2 Prior Stroke or TIA 2 V Vascular disease 1 A Age 65-74 years 1 Sc Female 1 CHADSVASc Score Stroke Risk % 0 0.2 1 0.6 2 2.2 3 3.2 4 4.8 5 7.2 6 9.7 7 11.2 8 10.8 9 12.2 Using http://www.mdcalc.com/cha2ds2-vasc-score-for-atrial-fibrillation-stroke-risk/ AC Protocols version 4.1 May 2017 4 Cardioversion The BSH recommend anticoagulation for 3 weeks before and for 4 weeks after cardioversion (Keeling, et al 2011). However the policy in Oxford is to anticoagulate for 4 weeks before and for 3 months afterwards. To minimise cardioversion cancellations due to low INRs on the day of the procedure we recommend a target INR of 3.0 prior to the procedure and 2.5 afterwards. Heart valve prostheses The risk of systemic embolism from prosthetic heart valves depends on the type of valve, its position and other factors that contribute to the patients’ risk of developing thrombosis, such as cardiac rhythm and dilatation. Mitral bioprosthetic valves The target INR is 2.5 for the first 3 months after valve insertion, after which oral anticoagulation is usually discontinued (long term anticoagulation may be required for other reasons such as atrial fibrillation) and replaced with aspirin (Whitlock, et al 2012). Aortic bioprosthetic valves Can start aspirin straight away with no need for initial warfarin (long term anticoagulation may be required for other reasons such as atrial fibrillation) (Whitlock, et al 2012). Mechanical valves The types of mechanical valves used in modern practice are typically less thrombogenic than older valves (see below) but there still are surviving patients with old style valves such as the Starr-Edwards in place. The BSH (Keeling, et al 2011) decided to adopt the European Society of Cardiology guidelines (Vahanian, et al 2007) but to restrict the highest recommended target INR to 3.5. Prosthesis INR target INR target Thrombogenicity* No patient risk factors Patient-related risk factors** present Low 2.5 3.0 Medium 3.0 3.5 High 3.5 3.5*** *Prosthesis thrombogenicity: Low: Carbomedics (aortic position), Medtronic Hall, St Jude Medical (without silzone) Medium: Bjork-Shiley, other bileaflet valves High: Starr-Edwards, Omniscience, Lillehei-Kaster. **Patient-related risk factors for thrombosis: Mitral, tricuspid or pulmonary position Previous arterial thromboembolism Atrial fibrillation Left atrium diameter >50 mm Mitral stenosis of any degree Left ventricular ejection fraction <35% Left atrial dense spontaneous echo contrast. ***Was 4.0 in ESC guideline. AC Protocols version 4.1 May 2017 5 We will take advice from the referring physician but will use this as a guide when the required information is available. The ACCP (Whitlock, et al 2012) suggest a target of 2.5 for mechanical aortic valves and 3.0 for mechanical mitral valves. This is simple and fits what ESC/BSH recommends for low risk valves, it is reasonable for us to recommend this if we have no other data but note that for patients at low risk of bleeding the ACCP recommend the addition of aspirin. Duration of treatment in venous thromboembolism (VTE) Patients with proximal DVT or PE should be treated for at least 3 months. A recent analysis of data from seven trials (Boutitie, et al 2011) concluded that three months of treatment achieves a similar risk of recurrent venous thromboembolism after stopping anticoagulation as a longer course of treatment. This was also found in a British study (Campbell, et al 2007). It is clear that patients with unprovoked proximal DVT or PE are at a higher risk of recurrence than those with a transient precipitating factor (Iorio, et al 2010) and it is therefore recommended that they should be considered for long-term anticoagulation (Kearon, et al 2012), we should take into account information that may help predict risk of recurrence and risk of bleeding in the individual patient. This includes the increased risk of recurrence in males, those with post thrombotic syndrome and perhaps those with a raised D-dimer after completing anticoagulation. It should also be taken into account that patients with an initial symptomatic PE are 3 to 4 times more likely to suffer recurrence with PE rather than DVT as compared with patients who present with an initial DVT. Commencement of oral anticoagulant therapy Standard induction regimen commenced with heparin cover Patients with VTE will commence treatment with (LMW) heparin. Warfarin can be started as soon as the diagnosis is confirmed. Heparin should be continued until the INR has been ≥ 2 for at least two consecutive days or for five days – whichever is the longer. Our warfarin induction schedule is shown in the table. We prefer starting with 5 mg rather than 10 mg as over-anticoagulation is less likely, particularly in the elderly and those with liver disease or cardiac failure. If the baseline INR≤1.3 the patient will receive 5mg of warfarin once daily on days 1 and 2. The INR is checked on day 3 and 4 and the warfarin dose is adjusted according to the schedule. days 1 & 2 day 3 day 4 INR dose INR dose Give 5 mg each day if < 1.5 10 mg < 1.6 10 mg baseline INR ≤ 1.3 1.5-2.0 5 mg 1.6-1.7 7 mg 2.1-2.5 3 mg 1.8-1.9 6 mg 2.6-3.0 1 mg 2.0-2.3 5 mg > 3.0 0 mg* 2.4-2.7 4 mg 2.8-3.0 3 mg 3.1-3.5 2 mg 3.6-4.0 1 mg > 4.0 0 mg* AC Protocols version 4.1 May 2017 6 * if required the thrombosis nurse (bleep 5035) or the haematology SpR can be contacted for advice on further management. Slow induction of anticoagulation in patients with atrial fibrillation without heparin cover (Janes, et al 2004) Exclusions Patients with baseline INR of >1.3 (discuss with a haematology doctor) Patients concurrently starting amiodarone, a statin, antibiotics or other drugs known to potentiate warfarin. Patients who have been on these drugs prior to starting warfarin can be included. If a patient has taken warfarin in the past their previous dose requirements should be considered. INR Dose Day 1-7 3 mg daily and check in 1 week Day 8* *This protocol is only valid if the patient has taken 7 days warfarin before the day 8 INR: otherwise it is invalid. You should be aware of early tests as the dose may be seriously overestimated. <1.4 Increase to 6 mg and check in 1 week (see Day 15 below) 1.4-1.5 Increase to 5 mg and check in 1 week 1.6-1.8 Increase to 4 mg and check in 1 week 1.9-2.1 Maintain 3 mg and check in 1 week 2.2-2.5 Reduce to 2.43 mg (17 mg per week) and check in 1 week 2.6-2.7 Reduce to 2 mg and check in 1 week 2.8-3.0 Omit 1 day, reduce to 1 mg and check in 1 week >3.0 Stop, check in 3-5 days.