Grasp-AF

Atrial Fibrillation (AF) is an irregularity of the pulse.
Having this irregular pulse puts the patient at an increased risk of having a stroke.
This risk can be reduced by taking aspirin or warfarin.
The risk of having a stroke increases with age so we tend to recommend warfarin for the older folk with AF.


So what is the risk?


If you are less than 65 with an otherwise healthy heart then the annual risk of stroke is about 1%
If you are between 65 and 75 that risk increases to 3% especially in those with diabetes or known vascular disease
Over 75 or anyone with a damaged heart valve or a previous stroke, the risk is nearer 6%



Imagine 1000 people at 1% risk of having a stroke each year.
Without treatment about 10 of them will have a stroke.
So 990 of them will not have a stroke. 



However, if those same 1000 people each take low dose aspirin, over a year:

• About 2 people will be ‘saved’ from having a stroke by taking aspirin
• About 8 people will still have a stroke, even though they take aspirin.




If we look at the 6% risk category in 1000 people it is likely that about 60 would have a stroke.



If those same 1000 people each take low dose aspirin, over a year: 


• About 12 people will be ‘saved’ from having a stroke by taking aspirin
• About 48 people will still have a stroke, even though they take aspirin. 


So aspirin seems more efficient the higher the risk.


Warfarin is better still and in this same higher risk group being on warfarin 36 people a year would not have a stroke because of being on warfarin; and only 24 would have a stroke even though they were on warfarin.


Statistically about 3 of those 1000 people in that year might have a serious haemorrhage because they were on warfarin. But it would save 21 more strokes than the aspirin, so in the end the benefits statistically outweigh the risks.


There is a document here called a "Patient Decision Aid"


This shows those same figures somewhat more graphically.
It is funny but when you look at the picture of 1000 people and who might have a stroke it seems to be to reduce the impact of the risk of a stroke.
BUT you just can't tell which patients are the ones that will be the ones to have a stroke.


We are moving now to attempting to identify more people with irregular pulses and will then try to decide individually with them whether to recommend taking aspirin or warfarin to reduce the risk of stroke.


We have something like 250-300 patients on our list with AF. I haven't sat down and risk assessed them individually but we must be looking at a potential half-dozen strokes a year without aspirin or warfarin, so that may translate into a couple of strokes a year avoided if we had the majority of patients on preventive treatment.