People with a common heart problem could be at higher risk of having a stroke or developing a form of dementia than previously thought, according to a study.
While some people with atrial fibrillation (AF) – an irregular heartbeat – are deemed to be at risk of having a stroke and given preventative medicine, others are not.
Academics said that the risk assessment tools used to decide who should be given these drugs only have “modest” capabilities.
They also do not factor in other blood clot-related illnesses such as vascular dementia – a form of dementia caused by reduced blood flow to the brain.
Researchers set out to assess whether people with AF deemed to be at low risk of developing strokes and other blood clots – who would not normally be prescribed blood thinners – may actually still suffer negative outcomes.
The team from the University of Birmingham examined data on more than five million people registered with UK GP practices.
Among these they identified 36,340 AF patients who had no history of stroke, a low perceived risk of stroke and no oral anticoagulant (blood thinners) prescription.
They were tracked for an average of five years to assess their risk of strokes, vascular dementia or death.
Their data was also compared with information held on 117,000 healthy people without AF.
Despite being in the low-risk group, some 3.8% of AF patients monitored had a stroke, compared with 1.5% of healthy people.
Some 9% of people with AF died compared with 5% of healthy people.
People with the condition had 68% increased odds of developing vascular dementia, according to the study, which has been published in the journal Nature Medicine.
Dipak Kotecha, professor of cardiology at the University of Birmingham and senior author of the study, said: “Atrial fibrillation is one of the most common heart conditions, with over 60 million cases expected worldwide by 2050.
“With its prevalence continuing to rise, it is crucial that we develop strategies to prevent not only stroke, but outcomes like dementia which are a big concern for patients and healthcare systems.
“Our research highlights the urgency of addressing AF comprehensively, considering its overall impact on the wellbeing of patients.”
Alastair Mobley, a PhD researcher at the University of Birmingham and first author of the study, said: “This study demonstrates a clear correlation between AF and vascular dementia.
“This may have a similar mechanism to the association between AF and stroke.
“Ongoing clinical trials such as DaRe2THINK, currently being run by the University of Birmingham, are exploring whether blood thinners in lower-risk patients can provide a way to prevent these bad outcomes.”
Atrial fibrillation is a heart condition that causes an irregular and often abnormally fast heart rate – in some cases people with the condition have a heart rate of more than 100 beats a minute.
It is the most common heart rhythm disturbance, affecting around 1.4 million people in the UK.
The condition has been linked to developing blood clots and there are “numerous” tools to estimate stroke risk among people with AF but researchers said that “these have only a modest predictive capacity” and they do not consider other outcomes such as vascular dementia.
The authors highlight how guidelines from the National Institute for Health and Care Excellence and others recommend anticoagulant use only in patients with an elevated stroke risk score.
They said that more trials are needed to asses whether patients with AF could benefit from earlier use of blood thinners to prevent these bad outcomes.
