Both very low and very high heart rates are significantly associated with stroke risk, novel study finds
(Wednesday, 6 May, Maastricht, the Netherlands) A new study presented today at the European Stroke Organisation Conference (ESOC) 2026 suggests that both very low and very high resting heart rates are linked with an increased risk of stroke.1
As the largest population-level study to examine this relationship, the findings challenge the assumption that lower heart rates are always a sign of good cardiovascular fitness and carry no risk.
In an analysis of the UK Biobank, researchers followed 460,000 participants for an average of 14 years, during which 12,290 strokes occurred. Analyses were adjusted for age, sex and cardiovascular risk factors, including atrial fibrillation – a heart condition that causes an irregular heartbeat and is a major cause of stroke.2
Stroke risk was lowest at resting heart rates of 60 to 69 beats per minute (bpm) but increased at both extremes – below 50 bpm and at or above 90 bpm – forming a clear U-shaped pattern. At these extremes, stroke risk was 25% higher in those with very low heart rates and 45% higher in those with very high heart rates.
Importantly, in the overall population, this relationship remained after adjustment for established stroke risk factors including hypertension, diabetes and atrial fibrillation, suggesting it reflects a genuine biological signal.
However, when participants were analysed separately, the pattern was only seen in people without atrial fibrillation. In those with the condition, the relationship was not apparent.
Lead author Dr Dexter Penn, from the Department of Brain Sciences at Imperial College London, explained: “This is likely because atrial fibrillation is such a strong risk factor for stroke, increasing risk by around fivefold, that it outweighs the contribution of heart rate and limits our ability to detect its effect. Heart rate was therefore most informative in people without atrial fibrillation, where it may provide a valuable additional tool for identifying and stratifying stroke risk.”
The researchers also explored the potential mechanisms underlying the relationship between heart rate and stroke. Very low heart rates were primarily associated with ischaemic stroke. This would be consistent with the hypothesis that very low heart rates could be associated with reduced blood flow to the brain by prolonging the relaxation phase between heartbeats.
In contrast, elevated heart rates were associated with both ischaemic and haemorrhagic stroke and may suggest increased stress on blood vessel walls that could contribute to both ischaemic injury and a greater predisposition to bleeding.
Commenting on the clinical implications of the findings, co-author Professor Alastair Webb, Clinical Associate Professor in Stroke Medicine, Department of Brain Sciences at Imperial, said: “Resting heart rate is a simple, widely available measure that deserves greater attention in cardiovascular risk assessment, particularly in people without atrial fibrillation. More research is required to understand why both low and high heart rates may be associated with an increased stroke risk and what implications this may have for treatment, but very low or very high heart rates should act as a signal for clinicians to look more closely at an individual’s overall cardiovascular risk and take action to reinforce lifestyle changes and standard prevention strategies.”
The authors emphasise that further research is needed to better understand whether resting heart rate plays a causal role in stroke or reflects underlying health. This will include studies exploring genetic factors linked to heart rate, as well as research using repeated or continuous monitoring to better capture how heart rate changes over time. It will also be important to confirm these findings in more diverse populations.
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Note to editors:
A reference to ESOC 2026 must be included in all coverage and/or articles associated with this study.
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About the study authors:
Dr Dexter Penn is an Alzheimer’s Research UK Clinical Fellow in Cerebrovascular Disease at Imperial College London. Since qualifying in medicine at the University of the West Indies in 2010, he has built a career spanning neurology, stroke medicine, dementia research, and entrepreneurship – including founding Kalgera, a fintech start-up that raised over £1 million to protect vulnerable people from financial exploitation. Dr Penn is a Fellow of the Royal College of Physicians and a Stroke Training Excellence Programme Fellow of the British and Irish Association of Stroke Physicians. Dr Penn’s PhD research focuses on the epidemiology and underlying physiologic mechanisms involved in stroke and vascular cognitive impairment.
Prof Alastair Webb is a Clinical Associate Professor in Stroke Medicine and a Vascular Neurologist at Imperial College London, providing clinical care for acute stroke patients and people with chronic cerebrovascular disease at Charing Cross Hospital. He leads the Imperial Small Vessel Disease Research Group, which focuses on cerebral small vessel disease and its associated cerebrovascular physiology, using big data, observational cohorts, experimental medicine and clinical trials to develop mechanism-based treatments to reduce the burden of this high impact disease.
His research began with a DPhil under the guidance of Professor Peter Rothwell at the Wolfson Centre for Prevention of Stroke and Dementia, University of Oxford, from 2010-2013, focussing on effects of antihypertensive medications on blood pressure variability and stroke risk in meta-analyses of randomised controlled clinical trials. He then defined the underlying physiological mechanisms in his physiological cohort within the population based ‘OXVASC’ study. Having identified novel physiological indices that predict the future risk of stroke, cerebral small vessel disease and cognitive impairment, this led to mechanistic clinical trials to identify new interventions such as the recently completed phase 2 OxHARP trial testing the effects of sildenafil on cerebral perfusion and endothelial function. Having moved to Imperial College London in 2024, he has established a new research program including the Miro-Dose experimental medicine study defining the role of PDE5 dysfunction in small vessel disease and the prospective ACCESS@ICL cohort study at Imperial College London that aims to better define the nature of small vessel disease and its underlying mechanisms.
He is the Divisional Director of Research for Medicine and Integrated Care at Imperial College Healthcare NHS Trust, the chair of the Scientific Committee of the British and Irish Association of Stroke Physicians and a member of the Board of Directors of the European Stroke Organisation.
About the European Stroke Organisation (ESO):
The ESO is a pan-European society of stroke researchers and physicians, national and regional stroke societies and lay organisations that was founded in December 2007.
The aim of the ESO is to reduce the burden of stroke by changing the way that stroke is viewed and treated. This can only be achieved by professional and public education, and by making institutional changes. ESO serves as the voice of stroke in Europe, harmonising stroke management across the whole of Europe and taking action to reduce the burden of stroke regionally and globally.
https://eso-stroke.org/
About Imperial College London:
Imperial is a world-leading university for science, technology, engineering, medicine and business (STEMB), where scientific imagination leads to world-changing impact.
As a global top ten university in London, it uses science to try to understand more of the universe and improve the lives of more people in it. Across its 10 campuses and throughout the Imperial Global network, its 22,000 students, 8,000 staff, and partners work together on scientific discovery, innovation and entrepreneurship. Their work addresses some of the world’s toughest challenges in global health, climate change, AI, business leadership and more.
Founded in 1907, Imperial’s future builds on a distinguished past, having pioneered penicillin, holography and fibre optics. Today, Imperial combines exceptional teaching, world-class facilities and a habit of interdisciplinary practice to unlock scientific imagination.
https://www.imperial.ac.uk/
References:
- Penn, D., Gill, F., Warrington, O., Webb, A. (2026). Reduced and elevated resting heart rates predict risk of stroke, independently of atrial fibrillation: A UK Biobank analysis. Oral presentation. European Stroke Organisation Conference (ESOC) 2026.
- Stroke Association. (n.d.). Atrial fibrillation. https://www.stroke.org.uk/health/atrial-fibrillation