Resting, Night-time, and 24 H Heart Rate as Risk Markers
Resting, Night-time, and 24 H Heart Rate as Risk Markers
Aims Increased heart rate (HR) is a predictor of all-cause and cardiovascular (CV) mortality. We tested which measure of HR had the strongest prognostic value in a population with no apparent heart disease.
Methods and results Six hundred and fifty-three men and women between the age of 55 and 75 years were included in the Copenhagen Holter Study and underwent 48 h ambulatory electrocardiographic (ECG) monitoring. Resting HR was measured after at least 10 min of rest. Twenty-four-hour HR was derived from the mean time between normal-to-normal RR intervals (MEANNN). Night-time HR was derived from a 15 min sequence between 2:00 and 2:15 a.m. The median follow-up time was 76 months, and an adverse outcome was defined as all-cause mortality and the combined endpoint of CV death, acute myocardial infarction (AMI), and revascularization. All three measures of HR were significantly associated with all-cause mortality, also after adjustment for conventional risk factors. We found an association between all three measures of HR and CV events in analyses adjusted for sex and age. However, when adjusting for CV risk factors, the association with resting HR and 24 h HR disappeared. In a fully adjusted model, only night-time HR remained in the model, hazard ratio = 1.17 (1.05–1.30), P = 0.005.
Conclusion In middle-aged subjects with no apparent heart disease, all measures of increased HR were associated with increased mortality and CV risk. However, night-time HR was the only parameter with prognostic importance after multivariable adjustment
Epidemiological studies have shown that resting heart rate (HR) is a predictor of all-cause mortality and cardiovascular (CV) mortality in subjects with as well as without diagnosed CV disease, and the effect is independent of traditional CV risk factors. Increased HR is associated with a poor prognosis, and the importance of resting HR as a risk factor in the general population is recognized by the European Guidelines on CV Prevention.
However, HR is a highly variable parameter that is influenced by numerous factors. The sino-atrial node (SA-node) is affected by physical and mental activities, sleep stages, and environmental factors through the autonomic nervous system, reflex regulation, and circulating hormones. HR has a circadian variation, with a higher HR during daytime compared with night-time. During non-rapid eye movement (REM) sleep, there is a relative vagal dominance in the regulation of HR. This phase is periodically interrupted by REM sleep, where HR increases as vagus nerve tone is withdrawn, and sympathetic nerve activity reaches levels higher than during waking.
It is not clear which measure of HR has the strongest prognostic value. Thus, a better estimate of an individual's habitual HR might be obtained from 24 h or night-time recordings compared with resting HR and hence a measure with a stronger prognostic value.
The aim of the present study was to compare the prognostic value for CV morbidity and mortality of resting HR, 24 h average HR, and night-time HR in middle-aged and elderly men and women with no apparent heart disease.
Abstract and Introduction
Abstract
Aims Increased heart rate (HR) is a predictor of all-cause and cardiovascular (CV) mortality. We tested which measure of HR had the strongest prognostic value in a population with no apparent heart disease.
Methods and results Six hundred and fifty-three men and women between the age of 55 and 75 years were included in the Copenhagen Holter Study and underwent 48 h ambulatory electrocardiographic (ECG) monitoring. Resting HR was measured after at least 10 min of rest. Twenty-four-hour HR was derived from the mean time between normal-to-normal RR intervals (MEANNN). Night-time HR was derived from a 15 min sequence between 2:00 and 2:15 a.m. The median follow-up time was 76 months, and an adverse outcome was defined as all-cause mortality and the combined endpoint of CV death, acute myocardial infarction (AMI), and revascularization. All three measures of HR were significantly associated with all-cause mortality, also after adjustment for conventional risk factors. We found an association between all three measures of HR and CV events in analyses adjusted for sex and age. However, when adjusting for CV risk factors, the association with resting HR and 24 h HR disappeared. In a fully adjusted model, only night-time HR remained in the model, hazard ratio = 1.17 (1.05–1.30), P = 0.005.
Conclusion In middle-aged subjects with no apparent heart disease, all measures of increased HR were associated with increased mortality and CV risk. However, night-time HR was the only parameter with prognostic importance after multivariable adjustment
Introduction
Epidemiological studies have shown that resting heart rate (HR) is a predictor of all-cause mortality and cardiovascular (CV) mortality in subjects with as well as without diagnosed CV disease, and the effect is independent of traditional CV risk factors. Increased HR is associated with a poor prognosis, and the importance of resting HR as a risk factor in the general population is recognized by the European Guidelines on CV Prevention.
However, HR is a highly variable parameter that is influenced by numerous factors. The sino-atrial node (SA-node) is affected by physical and mental activities, sleep stages, and environmental factors through the autonomic nervous system, reflex regulation, and circulating hormones. HR has a circadian variation, with a higher HR during daytime compared with night-time. During non-rapid eye movement (REM) sleep, there is a relative vagal dominance in the regulation of HR. This phase is periodically interrupted by REM sleep, where HR increases as vagus nerve tone is withdrawn, and sympathetic nerve activity reaches levels higher than during waking.
It is not clear which measure of HR has the strongest prognostic value. Thus, a better estimate of an individual's habitual HR might be obtained from 24 h or night-time recordings compared with resting HR and hence a measure with a stronger prognostic value.
The aim of the present study was to compare the prognostic value for CV morbidity and mortality of resting HR, 24 h average HR, and night-time HR in middle-aged and elderly men and women with no apparent heart disease.
