Both unusually slow and unusually fast resting heart rates are linked to a higher stroke risk than moderate heart rates, according to a large new study that challenges the common belief that lower is always better. Researchers analyzing data from nearly 460,000 people in the UK Biobank found a U-shaped relationship between resting heart rate and stroke risk, with the lowest danger zone falling between 60 and 69 beats per minute.

What Did the Study Actually Find About Heart Rate and Stroke?

The research, presented in May 2026 at the European Stroke Organisation Conference, tracked participants for an average of 14 years and recorded more than 12,000 stroke cases among people ages 40 to 69. The findings revealed a striking pattern: compared with people whose heart rates fell in the middle range, those with resting heart rates at or above 90 beats per minute had a 45% higher stroke risk, while those with heart rates below 50 beats per minute had a 25% higher risk, even after researchers adjusted for other stroke factors like age, blood pressure, and atrial fibrillation (AFib), an irregular heart rhythm condition.

The relationship between heart rate extremes and stroke risk appeared consistently across people without any history of AFib, suggesting that resting heart rate itself may serve as a useful health marker. "When we looked across the data, the lowest risk was in the middle, around 60 to 69 beats per minute, and increased at both ends," explained Dr. Dexter Penn, a clinical fellow in cerebrovascular disease at Imperial College London. "The common idea is that the higher the heart rate, the higher the stroke risk, but the relationship isn't as linear as it seems".

Dr. Dexter Penn, a clinical fellow in cerebrovascular disease at Imperial College London

"The common idea is that the higher the heart rate, the higher the stroke risk, but the relationship isn't as linear as it seems," said Dr. Dexter Penn.

Dr. Dexter Penn, Clinical Fellow in Cerebrovascular Disease at Imperial College London

Why Would Both Low and High Heart Rates Increase Stroke Danger?

The mechanisms behind this U-shaped pattern remain under investigation, but researchers have proposed plausible explanations. Very low heart rates may stretch the pause between heartbeats, potentially reducing steady blood flow to small brain vessels and making blockages more likely, according to Penn. Meanwhile, higher heart rates may increase stress on blood vessel walls, making them more vulnerable to both blockages and bleeds. When researchers broke down the data by stroke type, very low heart rates were specifically linked to ischemic stroke, which occurs when blood flow to the brain is blocked, while high heart rates were associated with both ischemic and hemorrhagic strokes, the latter involving bleeding in the brain.

The findings suggest that resting heart rate may act as a marker of underlying cardiovascular risk in people without diagnosed AFib. "That's likely because atrial fibrillation itself is such a strong risk factor that it masks any additional signal from heart rate," noted Alastair Webb, a stroke medicine researcher at Imperial College London. "In people without AFib, resting heart rate may act as a marker of underlying risk, though we need more data to confirm how reliable it is".

"In people without AFib, resting heart rate may act as a marker of underlying risk, though we need more data to confirm how reliable it is," noted Alastair Webb.

Alastair Webb, Stroke Medicine Researcher at Imperial College London

How to Monitor Your Heart Rate and Stroke Risk

• Know Your Baseline: Measure your resting heart rate by counting your pulse for one full minute when you're calm and haven't exercised recently, ideally in the morning before getting out of bed. A rate between 60 and 69 beats per minute appears safest based on current research.
• Track Changes Over Time: Monitor whether your resting heart rate shifts significantly from your normal baseline, as sudden changes may warrant a conversation with your doctor, particularly if you notice your rate consistently above 90 or below 50 beats per minute.
• Manage Traditional Risk Factors: Continue controlling established cardiovascular risk factors including high blood pressure, diabetes, and high cholesterol, as these remain the most important stroke prevention strategies regardless of your resting heart rate.
• Discuss Findings With Your Doctor: Mention any concerns about your resting heart rate to your healthcare provider, especially if you're at either extreme, so they can assess your individual risk profile and recommend appropriate monitoring or interventions.

Experts emphasize that the findings should not cause alarm among people with naturally low heart rates. "A low resting heart rate can still mean good fitness, particularly in physically active people," explained Webb. "But in others, it may be a useful signal worth considering alongside traditional risk factors".

"A low resting heart rate can still mean good fitness, particularly in physically active people. But in others, it may be a useful signal worth considering alongside traditional risk factors," said Alastair Webb.

Alastair Webb, Stroke Medicine Researcher at Imperial College London

Dr. Sanskriti Mishra, an assistant professor of neurology at Hackensack Meridian School of Medicine in New Jersey, noted that the results are clinically relevant because resting heart rate is easy to measure and may help flag cardiovascular risk in patients at either extreme. However, she emphasized that the findings are observational, meaning they cannot prove that high or low heart rate directly causes stroke. "I would advise people to mention it to their doctor and continue managing established cardiovascular risk factors, such as high blood pressure, diabetes and high cholesterol," Mishra stated.

"I would advise people to mention it to their doctor and continue managing established cardiovascular risk factors, such as high blood pressure, diabetes and high cholesterol," stated Dr. Sanskriti Mishra.

Dr. Sanskriti Mishra, Assistant Professor of Neurology at Hackensack Meridian School of Medicine

The study has not yet been published in a peer-reviewed journal, so these findings represent preliminary research that may be refined as additional evidence emerges. Nevertheless, the large sample size and long follow-up period make this one of the most comprehensive examinations of resting heart rate and stroke risk to date, offering valuable insights for both patients and healthcare providers seeking to identify and manage cardiovascular risk factors.