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AF Association
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Blood tests for clotting

On being diagnosed with AF you are usually subjected to a battery of tests but I am not aware of any I had related to the susceptibility of my blood to clot (i.e. its viscosity), which with the related stroke risk is commonly regarded as the real risk of AF.

I note from my GP/other records over the years (pre & post AF) I have had 'Platelets' around 200, 'Platelet size' around 7 and INR around 1, none of these taken or at least discussed with me to check on my individual blood viscosity re Af & strokes.

So the question to you more learned people is am I missing the point or is there a test which can usefully be done to be taken into account when making a decision on anticoags?

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Your Doctor will assess the risk of stroke vs the risk of bleeding in relation to the CHADS2VASC and HAS-BLED scores. If he considers an anticoagulant is appropriate he will discuss the options with you. They may include Warfarin or one of the newer anticoagulants. The information you mentioned regarding INR etc. is only relevant for Warfarin use, it's not relevant with the newer anticoagulants. The AFA association have some very good information on the site that explains about anticoagulants, the risks and choices etc. See here: heartrhythmalliance.org/afa... and here: heartrhythmalliance.org/afa...

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Thanks Drounding, my understanding is the CHADS/HASBLED don't involve any of the actual tests (e.g. as mentioned in my Q) on your blood itself; if they had they would no doubt flag up an extra point for Factor V Leiden (a gene abnormality), which I have and so does 10%+ of the population without knowing it. I have to point this issue out to cardiologists who usually then agree it should be taken into consideration.

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Interesting and common miss-conception .

VISCOSITY is the resistance of a liquid to pouring in other words how thick it is. (cream as opposed to milk.)

INR measures the speed at which your blood clots with the standard being 1. It has nothing to do with viscosity which does not change when taking Warfarin. (Other anticoagulants do not work in the same way and do not need testing. ) .

Platelets are the little blighters which stick together and in some people make their blood sticky and whilst this may be thought of as viscosity again it will not affect INR. Aspirin and clopidogrel are anti platelets which are usually prescribed where there is a risk of blood cells clinging to either on existing narrowing of an artery (plaque) or where artificial valves or stents have been installed. There are not anticoagulants and have very limited stroke prevention which is why aspirin is not recommended by NICE where AF is concerned.

Your stroke risk has nothing to do with blood viscosity as I think you will now understand but a lot to do with clots forming within the heart due to the irregular beating which can allow pooljng of blood especially in the left atrial appendage. Risk factors include high blood pressure (even if controlled) age. any prior coronary disease. diabetes, and of course any previous strokes or TIAs These are the CHADS of the Chadsvasc system with any vascular problems added in.

I hope that clarifies it a little.

You will also see that the term " blood thinner" so commonly miss-used is quite inappropriate.

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Thanks Bob, I knew with your motor sport experience you would pick up on viscosity! When I had my Sunbeam Imp Sport I looked after it with Castrol GTX. I personally may be a bit thick on this one but I find it odd in this day & age when it comes to clotting the use of multi comorbidity reasoning rather than a blood sample on a simple scale 1-10 - to say if you are in the top half of the range you are more likely to develop a clot in the left atrial appendage than if you are in the bottom half of the range your risk is reduced. It would certainly help me make up my mind quicker when I reach 65 this year.

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Because it really is not that simple. There are a range of co-morbities which affect stroke risk as explained. To put it another way Dr Gupta said a while back it is not the AF which presents the risk but the company it keeps.

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I am just reading CD and Bobs responses and LOL!! Here it is!!!

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Just to add - coagulation = INR testing is not about viscosity. Anti-coagulation is what we AFers need to concern ourselves with as giving anti-coagulation is a prophylactic treatment to prevent clots from forming.

Platelets maybe but they serve a different function in the body as they can clump and make blood ‘sticky’. Aspirin and other drugs are given to bust the platelet clumps and more often given after, rather than before an event - least that’s my layperson’s understanding.

Someone please correct me if I got that incorrect.....

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Thanks CDreamer, I clearly need to do some more homework on this.

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For a less scientific, but highly enlightening, account of the stroke risk for us AF patients, have a look at some of the videos on You Tube by Dr Sanjay Gupta at York Cardiology. Risk is a poorly understood concept by most people, but Dr Gupta manages to clarify the position well.

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Thanks Momist, I saw that video and as I am up in York soon, I am having a 'second opinion' consultation with Dr Gupta re my AF situation generally - hope he comes across as well as he does on video.

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Are you going to the Ebor Race meeting at York ?

Once I had been in AF all weekend and was not sure what to do on the Monday, stay home, go to the doctor or go to the races as intended. I went to the races and backed two outsiders in the first race who were involved in a very close finish that took the photo finish judge ages to announce. I was not really bothered which one won and would also have a huge Exacta. The two trainers were standing near me and each said that their hearts were racing waiting for the verdict and would settled for a dead heat.

After collecting my winnings I suddenly realised that I was back in NSR.

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No, I am going to watch cricket at Scarborough, great ground! Like the story at the races; the mind to convert back to NSR has been mentioned here but I for one would like to hear more from others who have used the mind unintentionally or intentionally and been successful.

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Does cricket excite you ?

When I first went to London on holiday as a 17 year old in 1952 I thought that I should go to Lords. It was the Gentlemen Vs the Players (very different now) and all the great players of the day. I was bored out of my mind and left at lunch time.

My next venture was a couple of years later when by then I lived in London. My cousin was playing for the War Office at Raynes Park and invited me along. That was no better but the tea was quite good. Various people have tried to explain the intricacies of the game but they go over my head. It must because I'm Scottish.

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The sports I like to watch now (and play) are the same ones I played when I was younger - that's the key to appreciation in most cases I suspect.

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Most are too commercialised with personality cults as well as being too expensive to attend. I gave up my football season ticket when I could no longer pronounce the players names and as with other sportsmen they moved out of our world.

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I was given a specific test that determines if you have a clot: the D-Dimer Test. Mine was positive. I was sent immediately to CT scans, ultrasounds and Echocardiogram and other physical tests so doctors could locate where the clot was. Unfortunately, the doctors could not find the clot. Sometimes you can get a positive D-Dimer when it hasn’t quite formed the clot. I’m so freaking blessed to get the help when I did.

D-dimer is one of the protein fragments produced when a blood clot dissolves in the body. It is normally undetectable unless the body is forming and breaking down blood clots. Then, its level in the blood can rise. This test detects D-dimer in the blood. This test is used to rule out a blood clot.

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Thanks April, I have had that too but I guess it is not the test to determine the level of your susceptibility to clot.

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That may be a question better suited for CDreamer and Bob. I guess I don’t know-sorry. I thought we are all suspectable to clotting given a lot of influencing factors, ie diet, lifestyle, hydration and other health conditions.

Those 2 (CDreamer and Bob have enormous wealth of common sense and specific knowledge on such things and have learned so much from them and others!🤣) I do hope you (and me) will get an answer. 😊.

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