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Patients with a diagnosis of atrial fibrillation (Afib) who are above the age of 65 or who have co-morbidities such as heart failure, diabetes, high blood pressure, vascular disease or previous strokes are believed to be at a higher risk of future strokes. There is overwhelming evidence that such patients should be started on lifelong stroke prevention medications.

All currently prescribed stroke-prevention medications seem to work by exerting an anticoagulant effect which reduce the ‘clottability’ of blood. The theory is that, in Afib, the heart is not pumping as effectively as it should and blood can therefore stagnate within the atria of the heart and a blood clot can form which can then dislodge and go to the brain and cause a stroke. Anticoagulants are often (and incorrectly) referred to as ‘blood thinners’.

The idea of having to take ‘blood thinners’ for life can be hugely daunting and anxiety-provoking for the patient. Many patients are rightly concerned about the risks of spontaneous or trauma induced bleeding.  Additionally many patients enjoy sporting pursuits where there is a somewhat higher risk of injury and the thought of having to curtail or be cautious during the activities that they enjoy can be very depressing. Patients are often also concerned about other side-effects that may arise from taking a chemical lifelong.

Here are some of the things that I talk to my (unsurprisingly) reluctant patients which help them understand things better to allow them to make a decision that they are more comfortable with.


  • 1) ‘Blood thinners don’t really thin your blood but actually stop your blood from clotting as quickly as it would normally and therefore should be more accurately referred to as anticoagulants. You won’t have thin blood as such.
  • 2) AF is associated with strokes and if you take an anticoagulant, you reduce your risk of stroke by 60%. Remember that how you feel and whether you have a stroke are two completely unrelated things. You can feel great and then one day have a stroke or you may feel grotty all the time and not have a stroke so it is very important to understand that you should not base your risk of having a stroke on how you feel or have been feeling. Please note that Aspirin is not an anticoagulant and at most will only reduce the risk by a measly 20%
  • 3) Strokes in AF are caused by the co-morbidities you carry and your age rather than by the Afib itself. The risk of strokes is based by calculating your CHADS2Vasc and the higher the score the greater the risk. Currently in the UK, if you have a CHADs2Vasc score of >=1 if you are a man and >=2 if you are a woman, it is recommended you go on anticoagulants for life. It doesn’t matter whether you are in Afib or not, the risk is the same.
  • 4) There are 2 major problems with anticoagulants that put people off them:

–   the first and most important is that anticoagulants carry a risk of causing bleeding (in association with an insult or spontaneously)

–   the second is that anticoagulants are a hassle to take and people also do worry about side effects, inconvenience and blood tests etc.

So lets work out why you may be worried about taking anticoagulants. If it is because they are a hassle and may cause side effects then there is some good news:

  • Not everyone gets side effects. If they do the side effects are reversible and it is likely that switching to a different anticoagulant may not cause the same side effects.
  • If you are concerned about the inconvenience of having to have regular blood tests then there now are newer anticoagulants called the NOACS (or DOACS) that do not require regular blood testing so it would be the same as taking any other medication.
  • If you are worried about bleeding then it is important to consider the following points:


  • 1) If you took a population of patients with AF and treated them with warfarin for 18 months, then you will prevent a stroke in 1 in every 25 patients and 1 in 384 patients will suffer a significant bleed in the brain.


  • 2) The risk of bleeding is generally low but increases with co-morbidities and can be minimised by reducing alcohol intake, controlling co-morbidities and good lifestyle.


  • 3) The risk of bleeding with the NOACs is no greater than with Aspirin. There is an interesting study which confirmed this called the AVERROES study.


  • 4) Most bleeding consists of minor bleeding which settles spontaneously and the half-life of the medications (esp the NOACs) is short.


  • 5) The NOACS have a 50% less likelihood of causing major intracranial bleeding than with warfarin


  • 6) Reversal agents are available for warfarin and Dabigatran which work very quickly. The other agents also now have a reversal agent called Andexxa


  • 7) There is a mechanical option by which the stroke risk can be reduced without subjecting the patient to long-term anticoagulation. The Watchman device is inserted into the heart by keyhole surgery and mechanically blocks the left atrial appendage which is where the clot usually forms. This device therefore prevents the clot that has formed from getting dislodged and travelling to the brain. Here is the link to a video I have done on this subject.


  • Currently the ESC (European Society of Cardiology) guidance acknowledges that perhaps we are overestimating the risks of stroke in patients who have low CHADS2Vasc scores and they have relaxed the recommendations for anticoagulation. The current ESC recommendations now are that that anticoagulation should be considered in male patients with a CHADS2VASC of 1 and recommended with a CHADS2VASC of 2 and in women, considered in patients with a CHADS2VASC score of 2 and recommended in patients with a CHADS2VASC of 3 or greater.


I hope you found this useful and I would love to hear your comments. Here is a link to a video I did on this subject a few years ago


Tags: afib, Atrial fibrillation, AF, blood thinners, stroke, watchman, DOACS, NOACS, AVERROES

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