Contrary to the conventional belief that a lower heart rate is better for cardiovascular health, new research suggests that stroke risk rises when resting heart rate falls outside a specific range.
On Monday local time, a team led by Dr. Dexter Penn of Imperial College London (ICL) presented findings at the European Stroke Organisation Conference (ESOC 2026) in Maastricht, the Netherlands, showing a "U-shaped relationship" between resting heart rate and stroke risk based on an analysis of UK Biobank data.
The large-scale cohort study tracked approximately 460,000 people over an average of 14 years, drawing on more than 12,000 stroke cases. The results remained consistent even after adjusting for major risk factors such as age, sex, hypertension and diabetes. Stroke risk was lowest in the 60-69 beats per minute range, and the further heart rate deviated from this range, the more clearly the risk increased.
Warning Zones Below 50 and Above 90 BPM: Risk Rises Up to 45%
The analysis found that stroke risk increased significantly when heart rate fell below 50 beats per minute or rose above 90. Risk was about 25% higher among those with very low heart rates and up to 45% higher among those with elevated rates.
The researchers said the association held even after adjusting for existing risk factors such as hypertension, diabetes and atrial fibrillation. They explained that an excessively low heart rate can prolong the cardiac diastolic phase and reduce blood flow to the brain, while a high heart rate can increase the burden on vessel walls, raising the risk of damage and hemorrhage.
"Heart Rate Is Not Just a Number": A Potential Warning Signal
Notably, the "U-shaped relationship" was more pronounced among people without atrial fibrillation.
"Atrial fibrillation is such a powerful factor that it raises stroke risk up to fivefold, which may relatively mask the impact of heart rate," said Dr. Penn, who led the study. "Heart rate could serve as a stroke risk assessment indicator, particularly in people without atrial fibrillation."
The research team stressed that because resting heart rate is a simple measurement, it should be used more actively in cardiovascular risk assessment going forward. Still, they noted that further research is needed to determine whether heart rate is a direct cause or a signal reflecting overall health status.
"When heart rate is excessively low or high, it can serve as a signal to more closely evaluate overall cardiovascular risk and to strengthen lifestyle improvements and standard prevention strategies," said Professor Alastair Webb of ICL, a co-author of the paper.
