You can read about the study in the European Heart Journal, the official Journal of the European Society of Cardiology.
The researchers say that tracking heart rate over time may provide a "profoundly simple and important marker of health issues that could become lethal but which also might be prevented with diagnosis and treatment."
Lead investigator, Dr. Peter Okin, a noted cardiologist at the Ronald O. Perelman Heart Institute of NewYork-Presbyterian/Weill Cornell and professor of medicine in the Division of Cardiology at Weill Cornell Medical College, said:
It is easy and inexpensive to determine heart rate, and in fact is done routinely in a doctor's office. But this study suggests that physicians need to track the pattern over a number of years, not just consider single readings.
Based on this study, we believe that an elevated heart rate seen over a number of years is worrisome, signifying that these patients need further evaluation to see what might be causing the high heart rate.
The researchers found that a resting heart rate of over 84 beats per minute that either developed or persisted over a 5-year period increased the risk of cardiovascular death by 55%, and raised the risk of death from any cause by 79%.
Although the 9,193 patients in the study had hypertension (high blood pressure), adjustments were made for this in the study, as well as for other cardiovascular risk factors.
The authors state that a healthy heart rate is between 60 and 80 beats per minute.
The study revealed that every extra ten beats per minute higher than a normal resting heart rate is linked to a 16% higher risk of death from cardiovascular disease and a 25% increased risk of death from all causes.
Dr. Okin points out that this is one of very few studies that examined alterations in pulse rates over time.
The idea is that because heart rates may go up or down over time in response to changes in a person's condition or response to a treatment, the predictive value of a single heart rate measurement is less valuable than measurements over time.
Dr. Okin said:
Heart rates can change day to day and year to year. It's like having a higher body temperature one day that goes away the next. Something caused the fever, but it has resolved, perhaps with treatment. Heart rate is the same over a longer time span. If it goes up and remains elevated, some disorder is likely to blame.
For example, high heart rate, among other things, is a marker of raised sympathetic nervous system activity, which itself is associated with increased heart ischemia, and is also linked to promoting atherosclerosis and susceptibility to arrhythmia.
9,193 patients from Scandinavia and the USA were enrolled in this study; it is a sub-analysis of the LIFE (Losartan Intervention For Endpoint) study. Two different treatments were tested - losartan versus atenolol for hypertension. The patients' heart rates were regularly monitored.
The patients were divided into two groups - those with a persistent heart rate of 84 beats per minute or more, and individuals who had less. 84 beats per minute was selected because previous studies had linked it to mortality risk.
814 (8.9%) of the patients died after a mean of nearly five years. 4.8% (438) of them from cardiovascular disease. After making adjustments for possible effects of randomized treatment, and other risk factors, such as age, sex, diabetes, medical history, etc., the scientists found a strong link between persistent elevated heart rate and risk of death.
Although the patients died from many different causes, Dr. Otkin said that heart rate remains a significant predictor of higher mortality.
Dr. Okin added:
In addition to high blood pressure, this study demonstrated that changing heart rate over time is a highly significant predictor of mortality.
No drug has been approved in the USA for the reduction of heart rate without side effects. Ivabradine, a medication, is currently being tested. The researchers say that exercise and diet can lower heart rate.
Written by Christian Nordqvist