For millions of people, a low dose of aspirin has become a morning routine along with brushing their teeth and reading the paper. Taking a baby aspirin, as the 75mg tablets are often called, has been sold as an easy, cheap and relatively risk-free way to cut the risk of stroke and heart attacks. However, over the summer the NHS changed its guidelines, saying that the pills are ineffective for those with heart rhythm disorders and that the risk of side effects in such cases outweighs the benefits.
The guidance published by Nice suggests a new generation of drugs is far better than aspirin at reducing the danger for such patients and is less likely to cause side effects including internal bleeding. So, who should be taking aspirin and who shouldn’t?
Firstly, it’s important to understand what aspirin does and how it works. Aspirin thins the blood and also acts as a painkiller. It’s been used by doctors for years to help patients at risk of developing blood clots, which can lead to heart attacks or strokes, including those with atrial fibrillation (abnormal heart rhythm). Blood clots cause strokes when they’re pumped from the heart to the brain, where the vessels are smaller and a clot can block them; it’s the resulting restriction of blood flow through the brain that’s a stroke. Aspirin is an ‘anti-platelet’ (as opposed to an anticoagulant, which we’ll come to later), meaning it reduces the stickiness of platelets in the blood, lowering the likelihood that blood will unnecessarily clot. The blood still has the ability to clot, but the chance of it happening is reduced and so the risk of having a stroke is also lower.
However, in those who have an abnormal heart rhythm, problems arise when you weigh up how effective aspirin is for this particular group of patients against its side effects. Another effect of aspirin is the regulation of stomach acid, which may lead to stomach ulcers. These are potentially very risky as they provide a site for the start of bleeding, and since the clotting ability of the blood is already reduced, there is a chance that the bleeding wouldn’t readily stop. The other drug options — anticoagulants, which block proteins involved in clotting — can also have internal bleeding as a side effect, and are traditionally seen as much more serious and powerful things than aspirin. (They’re also more expensive.) But Nice reckons that newer anticoagulants, such as dabigatran etexilate or rivaroxaban, reduce the risk of stroke in those with irregular heart rhythms much more than aspirin does, with about the same risk of side effects.
However, it is important to note that these new guidelines do not dismiss the clinical use of aspirin in stroke prevention completely. Indeed, they recognise it as the better choice in some cases. Nice is also clear in stating the new guidelines ‘do not apply to people with congenital heart disease precipitating atrial fibrillation’. The recommended course of treatment is dependent on the patient’s history; Nice is offering doctors a new online tool to help decide what to offer patients with persistent or permanent atrial fibrillation, atrial flutter or a continuing risk of the arrhythmia recurring once it’s been treated and turned back to normal. Meanwhile, in many instances — including lots of patients who have had a heart attack — aspirin is still recommended. If you know you have a heart rhythm problem and take aspirin or are otherwise high risk, then go to your GP and check if you should switch. For everyone else, keep calm and carry on.