NOACs

The New Approach To Stroke Prevention in Atrial Fibrillation

Telephone : 02477 220 180

[contact_bank form_id=4 show_title=false show_desc=false]

Asprin

  • Very good for preventing and treating non-haemorrhagic stroke in patients without AF
  • Acts by reducing the stickiness of platelets which are then less likely to form microclots in tiny blood vessels
  • Excellent at preventing ‘mini-strokes’ (TIAs)
  • Recent evidence suggests aspirin gives ‘little or no benefit’ in preventing strokes in patients with AF
  • NICE recommends converting patients who have AF and are on aspirin, straight over to NOACs

Atrial Fibrillation (AF)

Atrial fibrillation is an increasingly common heart rhythm abnormality that occurs in the older population.

  • It affects around 2 – 3% of the population in the western world and increases with age

  • 4% of 60 – 70 year olds

  • 14% (1 in 6) of the over 80s.

Although it is largely regarded as a ‘benign’ rhythm abnormality, it can lead to quite serious complications if not properly assessed and treated. Typically patients with AF have:

  • Irregularly, irregular pulse that may be fairly rapid and may have symptoms of

  • Tiredness,

  • Breathlessness and

  • Swelling of the ankles.

When severe and rapid, it may lead to heart failure, with complications of fluid on the lungs, infection and even death.

Conditions that may be associated with AF are:

  • Pneumonia

  • High blood pressure

  • Diabetes

  • Alcohol excess

  • Ischaemic heart disease (heart damage from hardening of the arteries)

  • Idiopathic (no obvious cause)

Stroke (CVA)

One of the potential serious complications of AF is the formation of blood clots in the left hand side of the heart.

These blood clots are unstable and can shoot off from the heart into the brain.

These blood clots can clog off the essential blood supply to brain tissue and even tiny blood clots can cause catastrophic damage, with that part of the brain losing its oxygen supply and dying.

This is known as ‘stroke’.

A stroke can have a severe ‘life-altering’ effect on patients, who may be:

  • Completely paralysed down one side of their body

  • Unable to speak

  • Unable to swallow

  • Unable to see properly and

  • When severe can cause death

  • Stroke is often irreversible.

 

The calculated risk for developing a stroke in patients with untreated AF is 5% (1 in 20) per year and for this reason there is a very strong argument for the use of anticoagulants in patients with AF to stop the formation of blood clots within the chambers of the heart.

Warfarin

Warfarin has been the main drug used in preventing stroke in patients in AF. It is:

  • Cheap

  • Well studied and

  • Has a good track record

But the downside is that in order for it to be effective, it has to be very closely monitored, with:

  • Regular blood tests,

  • Trips to the doctor and

  • Frequent dose changes

About 45% of patients on warfarin do not consistently maintain their blood tests within the recommended range, which makes them at risk of developing blood clots and strokes if their INR blood test is too low, or at risk of bleeding if their blood test is too high.

Some patients never achieve satisfactory blood tests and some are allergic to warfarin.

About 45% of patients on warfarin do not consistently maintain their blood tests within the recommended range, which makes them at risk of developing blood clots and strokes if their INR blood test is too low, or at risk of bleeding if their blood test is too high.

Some patients never achieve satisfactory blood tests and some are allergic to warfarin.

NOACs

Novel Oral Anti-Coagulants

There is a new class of drugs called ‘NOACs’. This stands for ‘novel oral anticoagulants’.

These drugs are very exciting in that the way in which they work:

  • Is absolutely predictable and therefore do not require frequent monitoring.

  • Their effect is fairly rapid (unlike warfarin which may take 3 days to reach the right level) and

  • The effect also wears off rapidly once they are stopped.

As you might expect the NOACs are significantly more expensive than warfarin and for this reason the current NICE guidelines suggest that patients should go on NOACs for the following reasons:

  • Inability to maintain blood tests at the right level while on warfarin

  • Allergy to warfarin

  • Conversion from aspirin onto anticoagulation

  • Genuine difficulty or inconvenience in attending for regular blood tests and GP appointments

As with warfarin there is a risk of haemorrhage, however in clinical studies, the risk of haemorrhagic stroke has been shown to be less in NOACs however their dose needs to be modified if the kidneys are not working properly so blood tests for kidney function need to be checked before starting and annually thereafter.

 

Should You be on a Proper Blood-Thinning Drug for your Atrial fibrillation?

Historically anti-platelet drugs such as aspirin have been used, but research has demonstrated that in AF, aspirin has little or no benefit.

 

 

  • There is a special formula for assessing the risk of developing a stroke with AF.

  • This is called the CHAD2DS2-VASc score.

  • This looks at all the risk factors for developing stroke and gives you a score.

  • A score of 1 and above puts you in the ‘moderate’ risk group.

  • As you can see from the formula, being female OR being over 65 puts you immediately in the moderate risk group.

  • There is an argument therefore that ALL patients with AF should be anticoagulated.

  • We believe that the vast majority of patients would opt for a NOAC for their sheer convenience.

  • NOACs should NOT be used if there is any history of rheumatic fever OR in patients who have significant heart valve defects.

  • There is a potential risk of haemorrhage with anticoagulants and any patient who scores more than 3 on the HAS-BLED scoring system would have to be very carefully considered for anticoagulation.

NICE Guidelines for:

Selecting Appropriate Patients for NOACs

Patients taking aspirin for stroke prevention are a priority group to consider. These patients can be directly switched from aspirin to a NOAC the next day.

There will be some patients currently taking warfarin for whom a switch to a NOAC is appropriate. These will include:

  • Patients on warfarin who, despite adequate adherence, spend less than 65% of time in therapeutic range, indicating suboptimal anticoagulant control.

  • New patients NOACs might be prescribed for newly diagnosed patients if this is the preferred option after discussion of the alternatives.

  • Patients with allergic reactions or intolerance to warfarin.

  • Patients who have genuine difficulty in attending for INR monitoring.

Online Medical Services – by Dr Helen Webberley

GMC no 3657058