Changes in resting heart rate and deaths from ischemic heart disease
Resting heart rate is a known predictor of cardiovascular risk. A recent CERG paper in the Journal of the American Medical Association shows that over a ten-year period, an increase in resting heart rate is associated with an increased risk of death from ischemic heart disease, as well as for all-cause mortality.
In a population-based prospective cohort study, 13,499 men and 15,826 women without known cardiovascular disease had their resting heart rate measured on two occasions, ten years apart, as part of the longitudinal Nord-Trøndelag County Health Study (HUNT). Over 12 years of follow-up, both deaths from ischemic heart disease (IHD) and all causes were recorded, and of the 3038 deaths observed, 975 were from cardiovascular disease and 388 were due to IHD.
Using people with a resting heart rate (RHR) of less than 70 bpm at both measurements as a control, statistical analysis showed that people whose RHR changed from less than 70 bpm to greater than 85 bpm had a 90 percent increased risk of death from IHD. Similarly there was an 80 percent increased risk in people with an initial RHR between 70-85 bpm, and a final RHR greater than 85 bpm. The results were similar for risk of death from all causes, with an increase in RHR associated with a higher risk of death, but the associations were generally weaker than those observed for IHD mortality.
The relationship between RHR and IHD mortality was not linear, which suggests that a decrease in RHR does not have a general mortality benefit. However, using people with a RHR between 70-85 bpm at both measurements as a control, it was observed that people in a subgroup with an initial RHR between 70-85 bpm and a final RHR lower than 70 bpm had a 40 percent lower IHD mortality, warranting further investigation.
It is also uncertain to which extent the findings can be extrapolated to less healthy individuals whose cardiovascular risk is already known to be high. Nevertheless, since resting heart rate and its relative changes over time are easy to obtain, its value as a prognostic marker could increase as a result of these findings. Recording RHR would be particularly relevant for early identification of asymptomatic people, who could benefit from primary intervention such as drug treatment or exercise training.
Link to the paper: http://www.ncbi.nlm.nih.gov/pubmed/22187277
This paper is part of the work included in Javaid's PhD dissertation, read more about his research here.
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