Heart rate

A determinant of myocardial oxygen demand, coronary bloodflow, heart performance, and is central to the adaptation of cardiac output to metabolic requirements.

Regulated by the autonomic nervous system.

Heart rate is determined by the intrinsic cardiac pacemaker activity of the heart along with the activities of the cardiac parasympathetic and sympathetic nerves. 

Heart rate is determined by the medulla oblongata and part of the pons, two organs located inferior to the hypothalamus on the brain stem. 

Baseline heart rate is a heritable trait
Some genetic loci for heart rate are also linked to regulation of the sympathovagal balance.
A higher heart rate is generally associated with prokinetic sympathomimetic activity with potential downstream effects.
Higher heart rate in normotensive patients is shown to precede the onset of blood pressure elevation later in life.

Higher heart rate is associated with cardiometabolic factors such as increased oxidative stress, inflammation, C reactive protein elevation, interleukin-6 elevation and increased fibrinogen, glucose intolerance, and diabetes.

An established biomarker affecting prognosis of cardiovascular processes.

Elevated resting heart rate associated with cardiovascular complications and poor outcomes in different disease states, including heart failure.

In some disease states such as heart failure, it is a modifiable risk factor because it’s reduction can provide benefits as to outcomes.

Peak heart rate is estimated to be 220 minus age for men and women.

Women have a higher resting heart rate at all ages.

Heart rate reserve is higher in men at all ages, due primarily to lower resting heart rate.

Peak heart rate is lower in younger women than in men.

Heart rate declines more slowly with age such that peak heart rate at ages 70-79 and 80-89 years is not significantly different between men and women.

Diabetes, smoking, obesity, poor exercise performance are associated with lower peak heart rate secondary to the less than maximal physiologic effort.

An inverse relationship exists between peak heart rate and age.

Resting heart rate predicts mortality after acute myocardial infarction.

HR is directly associated with survival in the general population, and in individuals with cardiovascular disease.

Heart rate is inversely associated with survival.

A higher resting heart rate is associated with increased risk of cardiovascular disease, including heart failure
Baseline and temporal changes in resting heart rate in young adults is associated with incident heart failure and cardiovascular disease by mid life.

Temporal increases in resting heart rate in patients followed up for a median of 26 years found smoking, higher alcohol intake, lower physical activity, male gender, and African-Americans had the greatest temporal increases in resting heart rate.

Temporal increases in resting heart rate is associated with impaired left ventricular relaxation and and worse diastolic function by middle-age.

For each 10 beats/min temporal rising resting heart rate there is an associate 38% and 23% higher risk of heart failure and cardiovascular disease, respectively.

HR associated with incident cardiovascular risk factors, such as impaired glucose metabolism, obesity, and diabetes.

Declining resting heart rates in the general population is to be perceived as having a parallel improvement in healthcare.

Positive association exists between cardiovascular mortality and transient hypertension and episodic heart rate increases.

In hypertension an increased heart rate during follow up is associated with mortality risk, where as a decrease in heart rate overtime is associated with lower

cardiovascular mortality.

Among patients with left ventricular hypertrophy increasing heart rate adds to cardiovascular mortality.

High heart rates are associated with markers of endothelial dysfunction, and with carotid and aortic arterial stiffness (Whelton SP et al).

In asymptomatic individuals, a higher heart rate is linked with sub clinical atherosclerosis because of lower coronary blood flow and atherogenic and endothelial shear stress patterns.

Higher heart rate is linked to microvascular and macrovascular degenerative target organ diseases.

Diabetics exhibit abnormal heart rate response to exercise, which are independently predictive of reduced long term survival.

Higher resting heart rate predicts for cardiovascular outcomes independent of

conventional risk factors and within subgroups of patients with cardiovascular disease.

Resting heart rate is modifiable overtime with respect to the interaction of genes and environmental factors such as exercise, medical conditions and medications.

HR is associated with severity of coronary atherosclerosis in young patients following myocardial infarction, and with coronary atherosclerosis progression of disease.

Cognitive decline, renal impairment, and endothelial dysfunction associated with high heart rate.

Higher heart rate is associated with less coronary and myocardial perfusion and lower diastolic filling time in the setting of increased myocardial oxygen consumption.
Heart rate is perceived to be a surrogate of basal metabolic rate and lower values have been linked with longevity.

In the Morbidity-Mortality Evaluation If-Inhibitor Ivabradine in Patients with Coronary Disease and Left ventricular Dysfunction (BEAUTIFUL) trial., HR of 70 beats or more per minute were associated with higher cardiovascular mortality, hospitalization for myocardial infarction and need for coronary revascularization compared with those with heart rates below 70 bpm.

In the BEAUTIFUL trial cardiovascular death and vascular events were not significantly reduced by ivabradine, however there was a significant reduction in need for revascularization and myocardial infarction in the subgroup of patients with a resting heart rate greater than 70 bpm.

Plaque ruptures associated with high heart rates.

Following stroke or myocardial infarction, or with proven vascular disease heart rate is directly associated with cardiovascular death, stroke, heart failure hospitalization.

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