Heart Rate And Strokes: Is There A Link?

Heart rate is an important indicator of cardiovascular health. While a high resting heart rate is associated with an increased risk of coronary heart disease and cardiovascular-related mortality, the relationship between heart rate and stroke is less clear. Some studies suggest that a high resting heart rate is associated with an increased risk of stroke, particularly in patients with hypertension. However, other studies have found no association between resting heart rate and stroke.

The REasons for Geographic and Racial Differences in Stroke (REGARDS) study found that high resting heart rates were associated with an increased risk of ischemic stroke compared to low heart rates. Similarly, a study of Chinese adults aged 40 and above found that elevated resting heart rates increased the risk of total and hemorrhagic stroke. In contrast, studies of the general French population and the Women's Health Initiative Study showed no link between resting heart rate and stroke.

It is important to note that the relationship between heart rate and stroke may depend on various factors such as age, sex, race, exercise habits, hypertension, and coronary heart disease. Additionally, the definition of a normal heart rate range is not standardized, and the measurement methods can vary between studies. Further research is needed to clarify the association between low heart rate and stroke risk, as well as the potential benefits of interventions aimed at reducing heart rate to prevent stroke.

High resting heart rates are associated with an increased risk of stroke

High Resting Heart Rates and Risk of Stroke

Mechanisms

Several mechanisms may explain the association between high resting heart rates and stroke:

• High resting heart rates are associated with higher levels of oxidative stress and endothelial dysfunction, which can lead to atherosclerosis and increased vascular resistance and blood pressure, predisposing individuals to stroke.
• High resting heart rates may reflect sympathetic overactivity, which is related to increased stress, anxiety, vascular stiffness, cardiac remodelling, atherosclerosis, metabolic changes, and pro-arrhythmic effects.
• High resting heart rates are associated with an increased risk of atrial fibrillation, which is a known risk factor for ischemic stroke.
• High resting heart rates may be a marker of chronic stress and anxiety, which have been linked to an increased risk of cancer and, potentially, stroke.

Implications

The findings suggest that interventions aimed at reducing resting heart rates may help decrease the risk of stroke, especially in individuals with hypertension. However, further research is needed to confirm these findings and determine the optimal resting heart rate for stroke prevention.

The association between resting heart rate and stroke remains unclear

The association between resting heart rate and stroke is not well understood. While some studies have found a link between elevated resting heart rate and an increased risk of stroke, others have found no association. This uncertainty may be due to differences in cohort characteristics, sample size, race, stroke subtype, resting heart rate measurement, and adjustment for confounding variables.

Conflicting Results

Several studies have reported conflicting results regarding the association between resting heart rate and stroke. Some studies have found that elevated resting heart rates are associated with an increased risk of stroke, while others have found no significant association.

For example, a study of 24,730 participants from the REasons for Geographic and Racial Differences in Stroke (REGARDS) study found that high resting heart rates were associated with an increased risk of ischemic stroke compared to low heart rates. However, reports from the general French population and the Women's Health Initiative Study have shown that resting heart rate is not associated with stroke.

Potential Explanations for Conflicting Results

The conflicting results regarding the association between resting heart rate and stroke may be attributed to several factors:

• Cohort characteristics: Differences in the characteristics of the study populations, such as age, sex, race, and medical history, may influence the association between resting heart rate and stroke.
• Sample size: Larger studies may have greater statistical power to detect associations that smaller studies may not.
• Race: Racial and ethnic differences in the association between resting heart rate and stroke may exist due to genetic, environmental, or social factors.
• Stroke subtype: The association between resting heart rate and stroke may vary depending on the type of stroke, such as ischemic or hemorrhagic stroke.
• Resting heart rate measurement: The method used to measure resting heart rate, such as electrocardiography or standardized electronic monitors, may impact the results.
• Adjustment for confounding variables: The inclusion or exclusion of certain confounding variables in the statistical analysis may influence the observed association between resting heart rate and stroke.

Mechanisms and Implications

Several mechanisms have been proposed to explain the potential association between elevated resting heart rate and stroke:

• Oxidative stress and endothelial dysfunction: Elevated resting heart rates are associated with higher levels of oxidative stress and endothelial dysfunction, which can lead to atherosclerosis and an increased risk of stroke.
• Vascular compliance: Lower heart rates improve vascular compliance, which is an important determinant of blood pressure and cardiac autonomic tone, potentially reducing the risk of stroke.
• Sympathetic over-activity: Elevated resting heart rates are often associated with sympathetic over-activity, which can reflect increased stress, anxiety, vascular stiffness, cardiac remodeling, and metabolic changes.
• Atrial fibrillation: Resting heart rate may be associated with the development of atrial fibrillation, which is a known risk factor for stroke.

Further research is needed to clarify the association between resting heart rate and stroke and to determine whether interventions aimed at reducing resting heart rate can decrease the risk of stroke.

Heart rate monitoring is recommended for acute stroke patients

Tachycardia (heart rate ≥120 beats per minute) and bradycardia (heart rate <45 beats per minute) are frequent phenomena in acute stroke patients. However, they do not independently predict clinical course or outcome.

In a study of 256 acute ischemic stroke patients, 39 patients (15%) experienced tachycardia, and 12 patients (5%) experienced bradycardia. Neither tachycardia nor bradycardia independently predicted poor outcome at three months.

Factors that predicted the occurrence of tachycardia included:

• Stroke severity (larger lesion size/higher NIHSS-score on admission)
• Atrial fibrillation
• Higher heart rate on admission

Factors that predicted the occurrence of bradycardia included:

Lower heart rate on admission

Elevated resting heart rate and hypertension are independently and jointly associated with the increased prevalence of stroke

Stroke is the leading cause of death in China and the second leading cause of death worldwide. Hypertension is a well-recognized major modifiable risk factor for stroke. However, the association between resting heart rate (RHR) and stroke remains unclear due to limited and inconsistent data. This study aims to evaluate the independent and joint effects of RHR and hypertension on the prevalence of stroke in a population-based cross-sectional study.

Methods

This cross-sectional study analyzed 14,677 participants from the China Hypertension Survey. The history of stroke was obtained through questionnaires, and RHR was measured by standardized electronic monitors. Multivariate logistic regression analyses were performed to evaluate the association between RHR, hypertension, and stroke. A generalized additive model (GAM) and smooth curve fitting were also conducted to assess the association between RHR and stroke in different hypertension status.

Results

The prevalence of stroke was 1.4% (221/14,677) in the study population. Each 10 beats per minute (bpm) increase in RHR was associated with an 18% increased prevalence of stroke (P = 0.017). Subjects with RHR > 80 bpm had a 47% higher prevalence of stroke (OR = 1.47; 95% CI, 1.08-2.01) compared to those with RHR ≤ 80 bpm. Similarly, hypertensives had a 3.76 times higher prevalence of stroke than normotensives (OR = 3.76; 95% CI, 2.39-5.92). Notably, hypertensives with RHR > 80 bpm had the highest prevalence of stroke compared to their counterparts (OR = 5.47; 95% CI, 3.13-9.56). The fully adjusted smooth curve fitting revealed a linear association between RHR and stroke among participants with hypertension but an almost horizontal association among participants without hypertension.

Elevated RHR and hypertension were independently and jointly associated with the increased prevalence of stroke. These findings suggest that elevated RHR is associated with an increased prevalence of stroke, especially among hypertensives. Further longitudinal investigations are needed to confirm these findings and examine the potential of heart rate-modifying therapies in preventing cerebrovascular events.

A high resting heart rate is associated with mortality in patients with acute ischaemic stroke and atrial fibrillation

A high resting heart rate is associated with an increased risk of coronary heart disease and cardiovascular-related mortality. However, the association between resting heart rate and stroke is unclear. While some studies have shown that high resting heart rates are associated with an increased risk of stroke, others have shown that resting heart rate is not associated with stroke.

A study of 24,730 participants from the REasons for Geographic and Racial Differences in Stroke (REGARDS) study found that high resting heart rates were associated with an increased risk of ischaemic stroke compared with low heart rates. Over a median follow-up of 7.6 years, a total of 646 ischaemic strokes occurred. Each 10 bpm increase in heart rate was associated with a 10% increase in the risk of ischaemic stroke. The results were consistent when the analysis was stratified by age, sex, race, exercise habits, hypertension, and coronary heart disease.

Another study of 3,447 acute ischaemic stroke patients from 22 hospitals in Suzhou City found that a higher resting heart rate (≥76 beats/min) was associated with an increase in the risk of in-hospital mortality among acute ischaemic stroke patients without atrial fibrillation (AF). During hospitalization, 124 patients (3.6%) died from all causes.

A high resting heart rate is also associated with higher mortality in patients with AF. A study of US outpatients with permanent AF in the Outcomes Registry for Better Informed Treatment of AF found that increasing heart rate >65 bpm was associated with higher all-cause mortality.

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