Sign In

Blood-thinning drugs to cut strokes

One in five of the patients admitted to hospital with a stroke have a heart rhythm disorder known as atrial fibrillation or AF.

The condition means that blood can pool in the heart, causing clots to form. People with AF are at five to six times greater risk of having a stroke which can often be fatal.

Although it can affect anyone, AF is more common the older we get, affecting almost one in ten of the over-80s. Overall, there are now more than one million people diagnosed with AF and many more who are thought to have it, but are unaware that they do.

By 2050, experts say these figures could double.

Trudie Lobban, founder and chief executive of the AF Association, says: “We know there are many people with AF who do not know they have it. In the first instance detection can be as simple as a pulse check.

“If you have AF and are at risk of an AF-related stroke, it is imperative you are assessed, and considered for anticoagulation medicine.

“We know that at least 7,100 AF-related strokes could be prevented every year if people with AF were appropriately treated.

“It is critical that greater awareness of AF and appropriate prescribing of effective therapies are NHS priorities – saving lives while also reducing cost to the NHS.”

The danger from AF occurs when the atria – the upper chambers in the heart – beat irregularly and the blood stagnates causing clots. When a clot forms, it can be pushed around the circulatory system and may get lodged in blood vessels in the brain, resulting in a stroke.

A large number of people diagnosed with AF are known to be at risk of stroke, but they are not receiving the anticoagulation they need, either because it isn’t offered to them or because it isn’t being used optimally

Fortunately, anticoagulants, often referred to as blood-thinning pills, can significantly reduce the risk of a stroke.

Warfarin, for example, is an anticoagulant that has been used since the 1950s. It is cheap, effective and well understood by doctors. But warfarin and other, more recently introduced, anticoagulant medicines are not always used.

In August 2013, data from the Sentinel Stroke National Audit Programme showed only one in three of the patients with AF who had a stroke were on anticoagulants such as warfarin.

This may be because getting the dose of warfarin right is not a simple process, and is complicated by the fact that it interacts with certain foods and alcohol.

Careful monitoring is needed and patients must go regularly to a special INR clinic to have a blood sample taken that ensures their dosage is correct.

Worse still, many AF patients are not prescribed anticoagulation therapy at all and are instead given aspirin. This may increase their risk of a bleed while doing little to reduce stroke risk.

Eve Knight, chief executive and co-founder of the charity AntiCoagulation Europe, says: “There are a large number of people diagnosed with AF who are known to be at risk of stroke, but they are not receiving the anticoagulation they need, either because it isn’t offered to them or because it isn’t being used optimally.”

The good news is that major changes should soon alter how AF patients are treated.

Existing guidelines from the European Society of Cardiology (ESC) will be bolstered in the forthcoming updated guidelines from the UK’s National Institute for Health and Care Excellence (NICE), which makes clear that anticoagulation is key.

The NICE guidelines will also include another important change for patients.

Three medicines that mark a significant innovation in anticoagulation for AF patients in more than half a century are now being recommended in the draft NICE guidelines which will be finalised and published in June.

Known as novel oral anticoagulants or NOACs, these medicines provide a fixed dose without the need for anticoagulation monitoring and eliminate the need to visit an INR clinic. Three NOACs are available on the NHS and all of them are at least as good as warfarin in reducing the risk of a stroke in AF patients.

While the ESC guidelines make clear that there is insufficient evidence to recommend one of these NOACs over another, they do point out that some patient characteristics, drug compliance, tolerability and cost may be important considerations in the choice of an agent.

In some parts of the UK, these more recently introduced medicines are already being embraced.

Craig Barr, a consultant cardiologist at the Dudley Group NHS Foundation Trust, says: “When we looked at the options available and all of the data, we felt that novel anticoagulants, which don’t require constant blood tests, were the best option for the majority of our patients. We now have options in anticoagulation management, whereas three years ago we didn’t. This means patients and doctors alike now have choice so that factors, such as age, lifestyle and preferences, can be taken into account when considering the treatment plan.”

Charities such as the Stroke Association say they hope that the new guidelines for doctors, combined with a wider range of treatments, will lead to a reduction in strokes.

Joe Korner, director of external affairs at the Stroke Association, says: “We know that people with AF are five times more likely to have a stroke and that it’s linked to around 22,500 strokes in the UK each year. That’s why it’s vital that people with AF get the right treatment as soon as possible. If the underlying conditions of stroke, such as AF, are picked up at an early stage and people get the right treatment, they can reduce their risk of stroke which will save lives.”

ANTICOAGULATION

Q&A

Patients with atrial fibrillation should always ask their doctor about the best treatment to reduce their risk of stroke. Dr Khalid Khan, consultant cardiologist at Wrexham Maelor Hospital, answers some common questions

Q: I’ve been diagnosed with AF, what is anticoagulation for?

A: The purpose of anticoagulation in AF is to reduce your chance of having a stroke. It achieves this by reducing the risk of clot formation in your heart that might then cause a stroke. We now have very good tools that can be used to estimate what your personal risk of having a stroke is. The calculation is based on known risk factors for stroke, including your age, sex and medical history, notably diabetes, high blood pressure, heart disease or a history of previous stroke. Based on these results, your doctor can advise you on whether you need anticoagulation and, if so, which approach is most suitable for you.

Q: What are the differences between the anticoagulants available?

A: Warfarin has been used for many years and is certainly effective when used correctly. Its downside is that it can be hard to get the dose right for some patients as warfarin’s action varies between individuals, and it can interact with certain foods and other medications. For this reason, you may need to go for regular blood tests at a clinic. There are three alternative anticoagulants to warfarin, called rivaroxaban, apixaban and dabigatran. These novel oral anticoagulants or NOACs are not affected by food or other drugs, so you do not need monitoring by regular blood tests. In terms of their ability to reduce your stroke risk, they are at least as good as warfarin, but some of the NOACs work differently to others. Your doctor can advise.

More recent evidence and international guidelines recognise that aspirin is much less effective in preventing stroke in atrial fibrillation

Q: I heard that the more recently introduced anticoagulants are more risky because they don’t have an antidote and so, if you start bleeding, it cannot be stopped, whereas warfarin has an antidote?

A: We have clear guidelines and measures that we can undertake to manage bleeding when it does occur, whatever a patient might be taking, including for the more recently introduced oral anticoagulants. The action of warfarin lasts for several days and an injection of vitamin K can reverse its effects, but this takes eight to twelve hours and is therefore not a true antidote (which reverses the effects immediately). Compared with warfarin, the blood thinning effect of NOACs wears off much faster. It is reassuring that in all the studies with the more recently introduced oral anticoagulants, they had at least a comparable safety profile to warfarin in terms of overall bleeding rates.

Q: My GP prescribed me aspirin as this follows current guidelines. Is this right?

A: Older guidelines from 2006 suggested that aspirin could be used in patients at low or medium risk of stroke. More recent evidence and international guidelines recognise that aspirin is much less effective in preventing stroke in AF, and is no safer than an anticoagulant in terms of bleeding risk. Guidelines due to be published by NICE in June are expected to recommend anticoagulation for all patients who are thought to be at risk of stroke from AF.

Q: Does age affect how I should be treated for my AF?

A: As you get older, both your chance of having AF and your chance of having a stroke increase significantly. Older patients also have a somewhat higher bleeding risk with anticoagulation. However, overall, older patients are more likely to benefit from receiving anticoagulation when compared to younger patients. The risks and benefits of treatment should be considered for every individual to ensure the anticoagulation they receive is appropriate for them. Your own doctor, with knowledge of your medical history, is in the best position to advise you of the most appropriate treatment.