A low resting heart rate is often considered a sign of good health, but new research suggests both very low and very high heart rates may be linked to an increased risk of stroke.
Presented at the European Stroke Organisation Conference 2026 in Maastricht, Netherlands, the study analyzed data from nearly 460,000 people in the UK Biobank. Over an average 14-year follow-up, researchers recorded more than 12,000 strokes.
Compared to those with heart rates between 60 and 69 beats per minute (bpm), people with rates at or above 90 bpm had a 45% higher stroke risk. Those with rates below 50 bpm had a 25% higher risk-even after adjusting for age, blood pressure, and atrial fibrillation.
Dr. Dexter Penn of Imperial College London said, "The lowest risk was in the middle, around 60 to 69 bpm, and increased at both ends."
The U-shaped pattern persisted in people without a history of atrial fibrillation, as that condition itself is such a strong risk factor it can mask other signals.
Low heart rates were specifically linked to ischemic stroke, caused by blocked blood flow. High heart rates were associated with both ischemic and hemorrhagic strokes.
Dr. Alastair Webb, co-author and stroke researcher, cautioned that a low resting heart rate can still mean good fitness, especially in physically active people. "But in others, it may be a useful signal worth considering alongside traditional risk factors."
The findings are observational and have not yet been published in a peer-reviewed journal.