ESOC 2026
Too high, too low: heart rate extremes raise stroke risk
Clinical takeaway: Resting heart rate at either extreme should prompt a closer look at overall cardiovascular risk, particularly in patients without atrial fibrillation where the heart rate signal is most informative.
Resting heart rate is one of the simplest measures in clinical medicine, yet its role in stroke risk has been unclear. Lower rates have generally been treated as a marker of fitness rather than risk. This UK Biobank analysis examined how resting heart rate relates to stroke incidence over long-term follow-up and whether the relationship holds independent of established risk factors.
Stroke risk was lowest at resting heart rates of 60 to 69 beats per minute and rose at both extremes. Compared with that reference range, risk was 25% higher at rates below 50 bpm and 45% higher at rates of 90 bpm or above. The U-shaped pattern persisted after adjustment for age, sex, hypertension, diabetes, and atrial fibrillation.
The mechanisms appear to differ at each end of the curve. Very low heart rates were primarily linked to ischemic stroke, consistent with reduced blood flow to the brain between heartbeats. Elevated heart rates were tied to both ischemic and hemorrhagic stroke, possibly reflecting added stress on vessel walls that could drive both clotting and bleeding.
The signal was driven by patients without atrial fibrillation. But in those with atrial fibrillation, no clear relationship between heart rate and stroke risk emerged — likely because atrial fibrillation itself raises stroke risk roughly fivefold, overshadowing the heart rate contribution. That finding sharpens the clinical use case: resting heart rate may be most informative as a risk-stratification tool in the broader population without known atrial fibrillation.
The analysis followed 460,000 UK Biobank participants for a median of 14 years, during which 12,290 strokes occurred. Findings have not yet undergone full peer review. Resting heart rate was measured at baseline, so the analysis cannot capture how rate variability or trajectory over time relates to risk.
"Resting heart rate is a simple, widely available measure that deserves greater attention in cardiovascular risk assessment, particularly in people without atrial fibrillation," said co-author Alastair Webb, clinical associate professor in stroke medicine at Imperial College London. "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."
Source: Penn D. European Stroke Organisation Conference 2026. Reduced and elevated resting heart rates predict risk of stroke, independently of atrial fibrillation: a UK Biobank analysis