Atrial fibrillation and warfarin[1]

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By: mblokesh (114 month(s) ago)

nice presentation. i need this for academic purpose. can u pls allow me to download or mail me to mblokesh@gmail.com. thanks in advance

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Atrial fibrillation and warfarin : 

Atrial fibrillation and warfarin Samir Dawlatly Group B2 4 September 2008

Aims and objectives : 

Aims and objectives Critically appraise QOF targets for AF What are the current QOF targets for the above areas? How have they changed? What is the evidence behind the targets? Consider the merits of warfarin for AF Cases to illustrate areas of debate? What are the risks of stroke when you have AF What benefit is there of being on warfarin? (absolute and relative) What are the risks of being on warfarin? – quantify if possible What type of patient would you not put on warfarin? What type of patient would you be unsure about?

QOF Atrial fibrillation targets : 

QOF Atrial fibrillation targets

How they have changed : 

How they have changed Not in 2004 guidelines Was almost part of Stroke 9 AF 4 states ECG required within 3 months of diagnosis (expert panel advice)

Rationale and evidence behind the targets : 

Rationale and evidence behind the targets AF associated with a 5 fold increase in risk of stroke (Wolf et al. Stroke 1991; 22: 983-88). One percent of a typical practice population will be in AF; 5% of over 65s, and 9% of over 75s

AF1: Having a Register : 

AF1: Having a Register good professional practice a building block for further evidence based interventions. Makes it possible to call and recall patients effectively to provide systematic care and to audit care. should include all people with an initial event; paroxysmal; persistent and permanent AF.

AF4: Confirming diagnosis : 

AF4: Confirming diagnosis AF is historically too often inaccurately coded more accurate register treatments are targeted more appropriately

AF3: patients on anticoagulant or antiplatelet : 

AF3: patients on anticoagulant or antiplatelet Relative risk of stroke substantially reduced by warfarin (66 %) (Arch Intern Med 1994; 154: 1449-57) BUT Warfarin carries a higher risk of serious haemorrhage than aspirin, and these risks are higher in older people (Van Walraven et al. JAMA 2002; 288: 2441-8) – 3x risk NICE Grade A evidence. Warfarin or phenindione

AF3 contd… : 

AF3 contd… Aspirin reduces relative risk of stroke by 22 %(Antithrombotic trialists’ collaboration BMJ 2002; 324: 71-86) NICE Grade A evidence. Can have aspirin, clopidogrel or dipyridamole

Talking about risks – Archives meta-analysis : 

Talking about risks – Archives meta-analysis Stroke incidence in trial quoted: No warfarin 4.5% (of 1802 = 81 patients) Warfarin 1.4% (of 1889 = 26 patients) Relative risk reduction = 66.6% - i.e chance of having stroke is 3x less) Absolute risk reduction = 3.1% (reduction from 45 in 1000 to 14 in 1000) NNT is 32 Personal probability of benefit is 3% (i.e. 97% of people who are put on warfarin for AF would never have had a stroke)

Talking about risks – JAMA paper (also a meta-analysis) : 

Talking about risks – JAMA paper (also a meta-analysis) Stroke incidence in trial quoted: No warfarin 4.5 per 100 patient years Warfarin 2.4 per 100 patient years Relative risk reduction = 53.3% - i.e chance of having stroke is <2 times less) Absolute risk reduction = 2.1 per 100 patient years (reduction from 45 in 1000 to 24 in 1000)

Risk of haemorrhage : 

Risk of haemorrhage JAMA paper “Treating 1000 patients with AF for 1 year with oral anticoagulant rather than aspirin would prevent 23 ischemic strokes while causing 9 additional major bleeds” 2.2 vs 1.3 events per 100 patient-years; (HR, 1.71) Annals paper 1.0% vs 1.3%

Heart 2006:92:196-200 : 

Heart 2006:92:196-200 6108 patients with AF, 36.4% received warfarin. Mean survival in the warfarin and non-warfarin groups was 52.0 months and 38.2 months, respectively (p , 0.001), and 14.4 months (p , 0.001) after adjustment for confounding factors. The risk of stroke in the warfarin group vs. non-warfarin group (relative rate (RR) 0.74, p , 0.001). The risk of death from ischaemic stroke was lower in the warfarin group (RR 0.43, p , 0.001). The risk of all ischaemic and embolic events in the warfarin group was lower when they were taking warfarin (RR 0.74, p , 0.001). The risk of bleeding in the warfarin group when treated was greater (HR 1.78, p = 0.001).

Communicating risk : 

Communicating risk “You are 30 to 78% more likely to have a brain haemorrhage on warfarin” “If you don’t take warfarin you are 2 to 3 times more likely to have a stroke” “Trials show that taking warfarin reduces your chance of having a stroke, but slightly increase your chance of having a major bleeding problem, including a brain haemorrhage. The balance is probably in favour of taking warfarin…”

AF Case 1 : 

AF Case 1 A 62 year old doctor has discovered that he has paroxysmal AF. This is confirmed on ECG. He is not diabetic, hypertensive or had a previous stroke. He is not symptomatic Should he be on warfarin

AF Case 2 : 

AF Case 2 Ernest is 78 and has early dementia He has a pill box and 3 carers a day You recently confirmed (with ECG) that he has AF after a fall He has had a TIA in the past and is hypertensive You also suspect that he has a degree of heart failure

AF Case 3 : 

AF Case 3 Mavis is 85 years old and lives in a residential home She has had 3 or 4 admissions with falls in the last 6 months She was diagnosed with AF on her last admission She is diabetic, hypertensive, and has had a CVA 2 years ago Should you put her on warfarin

Deciding who goes on warfarin : 

Deciding who goes on warfarin CHADS2 scoring system Congestive heart failure 1 Hypertension (systolic >160 mmHg) 1 Age greater than 75 years 1 Diabetes 1 Prior cerebral ischaemia 2

Slide 20: 

?which tables?

Be cautious with warfarin if… : 

Be cautious with warfarin if… Baseline INR is raised Abnormal LFT’s Cardiac failure Intravenous nutrition Low body weight Elderly Drugs that potentiate warfarin

What the BNF says : 

What the BNF says BNF contraindications Peptic ulcer Severe hypertension Renal impairment Pregnancy BNF cautions Recent surgery Bacterial endocarditis Hepatic impairment Breast feeding

Other situations you might not use it : 

Other situations you might not use it Recurrent falls Risk of intracranial bleeding Cognitive impairment or concordance issues Pt has to engage with treatment Previous cerebral bleed

Thank you : 

Thank you Any questions or comments

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