Study Reveals Both High and Low Resting Heart Rates Increase Stroke Risk Researchers from Imperial College London found that both very high and very low resting heart rates are associated with an increased risk of stroke, challenging the notion that a lower heart rate is always beneficial. The study, involving 460,000 participants, showed that heart rates below 50 bpm and at or above 90 bpm were linked to higher stroke risks, with the optimal range being 60 to 69 bpm. The findings suggest that heart rate could be a useful tool for assessing stroke risk, particularly in individuals without atrial fibrillation. A new study from Imperial College London has revealed that both very high and very low resting heart rates can significantly increase the risk of stroke, challenging the long-held belief that a lower heart rate is always a sign of good cardiovascular health. The research, which followed 460,000 participants from the UK Biobank over approximately 14 years, found that individuals with resting heart rates below 50 beats per minute (bpm) had a 25% higher risk of stroke, while those with rates at or above 90 bpm faced a 45% increased risk. The optimal range for minimizing stroke risk was identified as 60 to 69 bpm.The study accounted for established risk factors such as high blood pressure, diabetes, and atrial fibrillation, suggesting that the relationship between heart rate and stroke risk is biologically significant. Interestingly, the link between heart rate and stroke risk was not observed in individuals with atrial fibrillation, likely because this condition itself increases stroke risk fivefold, overshadowing the impact of heart rate.Dr. Dexter Penn, the lead author and a neurologist, noted that heart rate could serve as a valuable tool for assessing stroke risk, particularly in those without atrial fibrillation. The findings were presented at the European Stroke Organisation Conference, where researchers proposed that very low heart rates, known as bradycardia, may reduce blood flow to the brain, leading to ischemic strokes—the most common type, accounting for 85% of cases. Symptoms of bradycardia include dizziness, shortness of breath, confusion, and fainting.Conversely, very high heart rates were linked to both ischemic and hemorrhagic strokes, which occur due to bleeding in or around the brain. The researchers suggested that elevated heart rates may increase stress on blood vessel walls, contributing to blockages and a higher likelihood of bleeding. Atherosclerosis, the buildup of fatty material in arteries, and the formation of clots that can travel to the brain were also implicated in the increased stroke risk.Professor Alastair Webb, a co-author and stroke medicine expert, emphasized the importance of resting heart rate as a simple yet valuable measure in cardiovascular risk assessment. He recommended that clinicians pay closer attention to heart rates outside the normal range, reinforcing lifestyle changes and standard prevention strategies. The study underscores the need for further research to understand how heart rate influences treatment and prevention, but it offers promising insights into stroke risk stratification.Resting heart rate, defined as the number of heartbeats per minute while at rest, typically ranges between 60 and 100 bpm for most adults. Athletes, fit individuals, and those on beta-blockers often have lower resting heart rates due to improved cardiac efficiency. Regular cardiovascular exercise is known to enhance heart function, reducing the risk of major heart events.However, the study highlights that heart rates at either extreme—whether too low or too high—should prompt further evaluation of an individual's overall cardiovascular health