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HowToPreventHeartDisease.com |
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Is Abnormal Heart Rate A Risk Factor For Heart Disease? Diabetes, hypertension (high blood pressure), high blood cholesterol, overweight or obesity, smoking, tipple, unhealthy diet and sedentary lifestyle are some of traditional risk factors for heart disease. Recently, researchers from the Heart Rate Variability Laboratory at Washington University School of Medicine in St. Louis found that abnormal heart rate turbulence (HRT) is also associated with a higher risk of heart disease death. Their paper appeared in the Feb. 15 issue of the “Journal of Cardiovascular Electrophysiology”. National Heart, Lung, and Blood Institute (NHLBI), which is part of the National Institutes of Health, and the National Institute of Neurological Disorders and Stroke, jointly funded the study. While C-reactive protein (CRP) has emerged to be a potential heart disease biomarker in recent years, the researchers found that HRT could be an even stronger heart disease risk factor than elevated levels of CRP. HRT reflects how well the heart reacts to occasional premature contractions. Being part of the NHLBI’s Cardiovascular Health Study, the study followed a total of 1,272 adults aged 65 and older. The participants were divided into 3 groups: healthy group (no sign of heart disease risk except possibly diabetes), subclinical group (some signs of heart disease) and clinical group (had a cardiovascular event like heart attack).
At the beginning of the study, all participants underwent 24-hour monitoring of their hearts’ electrical activity through a small electrocardiographic (ECG) device known as Holter monitor that was attacked to their skin. The magnitude of the initial heart rate jump (turbulence onset) and the speed at which heart rate returns to normal (turbulence slope) were measured. Then, the researchers determined whether the heart rate turbulence response was normal. About 7 percent of the study participants had abnormal HRT, which predicted increased likelihood of heart disease death. Study participants classified as low risk of heart disease were 8 to 9 times more likely to die of heart disease if they had abnormal HRT during the 14-year follow-up. Those individuals, who were at low risk of heart disease and also had elevated CRP, were 2.5 times more likely to die than those with normal or low CRP. Traditional risk factors for heart are no doubt important, but both abnormal HRT and CRP levels were independently correlated to an increased likelihood of dying of heart disease, particularly in the healthy group, even after taking into account of other risk factors. Though abnormal HRT also predicted a higher likelihood of heart disease death in the other 2 groups, the results were not as pronounced as in the healthy group. According to the researchers, HRT measurements is insightful as it reveals a sign of how well the autonomic nervous system functions. Inability of a person’s heart to react well to the uncoordinated beats might indicate that the heart is also not good at reacting to other issues such as sudden stress or severe arrhythmias. The new findings suggested that apparently healthy people might be at higher risk of death from cardiovascular disease, and HRT that has potential value in diagnostic settings may help identify them. While measurement of HRT is not widely available presently, interest might now grow within the medical community to measure HRT in clinical practice because of the new findings. In addition to heart disease prediction, it is believed that HRT could also be used for heart disease prevention in the near future. In order to assess if HRT can be a clinically valuable tool, more studies should be replicated in other patient populations and should be done as an add-on to testing for CRP levels. No knowledge is currently available on whether abnormal HRT could be treated or prevented but it is hoped that scientists could eventually find some therapies that could be used to change this kind of abnormal response.
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