AF Association
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FAQs - Anticoagulants

Anti-Coagulation and “warfarin”

Q) I’ve been told I have to go on warfarin. That’s rat poison isn’t it?

A) Yes, warfarin is used as an anticoagulant and anticoagulants are used in rat poison. It is, however, many people’s best friend as it helps to protect those with AF from stroke.

Q) But you have to keep to a strict diet and have lots of blood tests and things don’t you?

A) Not necessarily. Provided that you have a normal diet and do not suddenly binge on any one food then your INR, the level at which your blood clots and a measure of how effective the warfarin is being, will be adjusted over time by the anticoagulation nurse or clinic. After a while you should settle down to a reasonably stable level and then probably only need blood tests once a month or even further apart.

Q) But aren’t there things I can’t eat and drink?

A)AF Association has produced a Warfarin & Diet fact sheet which offers advice on diet. You should also ask for advice at the anticoagulation clinic.

Q) Does it matter how much warfarin I have to take?

A) No, the actual dose is not relevant what matters is the INR level which should be between 2 and 3. Some people stay in range with relatively small doses whilst others may need much higher levels. We are all different you see and react differently to the medicine.

Q) But what if I cut myself?

A) Unless you really do some damage you may find that you bleed for a little longer than before but usually some pressure or a plaster over the cut will help it to stop. Most people on warfarin live perfectly normal lives.

Q) Will I bruise more easily?

A) Maybe yes but again we are all different. There are people who are not on the drug who bruise if you look at them whilst others really need to hit something hard to see a bruise.

Q) Will my hair start to fall out?

A)Some people have reported thinning of the hair and others that fingernails get brittle but everyone is different and it can be a small price to pay for the security of stoke prevention.

Q) What if warfarin doesn’t suit me or I can’t tolerate it?

A)There are a very few people for whom warfarin is unsuitable either due to bad reaction or possibly a previous history of stomach bleeding or ulcers . For those people obviously aspirin is equally ruled out. Fortunately there are now three new oral anticoagulants which a doctor could prescribe in such circumstances but being new they are more expensive than warfarin so most doctors would want to try warfarin first.

Q) What is CHA2DS2-VASc?

A) The CHA2DS2-VASc score is a modification of the CHADS2 score that aims to improve stroke risk prediction in patients with atrial fibrillation (AF) by adding three risk factors: age 65–74, female sex, and history of vascular disease.

CHA2DS2-VASc score:

C = congestive heart failure

H = hypertension

A2 = age > 75

D = diabetes mellitus

S2 = prior stroke or TIA (2 points)

V = vascular disease (MI, PVD etc)

A = age > 65

Sc = sex category (female = 1 point)

Women only score their gender point if they score another point elsewhere. A woman cannot have a score of just 1. A score of 1+ indicates that you have a higher than average risk of AF related stroke and an anticoagulant should be suggested dependent on personal circumstances. Even with a score of 0, there are some patients with AF who prefer to take an anticoagulant for stroke prevention and piece of mind.

Q) What are the alternatives to warfarin?

A) There are three new novel anticoagulants (NOACs). These are apixaban, dabigatran and


•Apixaban requires no blood monitoring because it acts on different areas of the blood thinning process than warfarin. An INR test is not required because apixaban does not stop the production of vitamin K in the coagulation process. It is taken twice daily and must be taken an instructed. There is as yet no antidote for apixaban, but its potency in the body greatly reduced after a matter of hours.

•Dabigatran has been shown to be non-inferior – or at least as effective as – warfarin. It only affects the part of the clotting cascade; as fibrinogen is converted to fibrin to produce a clot. Dabigatran is taken twice daily and the dosage will be decided by your clinician depending on your age and other factors. There is no need for routine monitoring and although it doesn’t have an antidote at this time, it works its way out of the system much quicker than warfarin.

•Rivaroxaban has been shown to be non-inferior to warfarin. It only affects one part of the clotting cascade. Unlike warfarin, rivaroxaban is taken once daily and the dose remains constant. The dosage will be decided by your clinician depending on your age and other factors. There is currently no antidote but rivaroxaban has a shorter half-life.

AF Association has various publications regarding anticoagulation available from the website:

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