Heart Rate Recovery After Exercise Helps Predict RisksStress Test Response Is Key< September 17, 2003 >Exercise testing not only helps predict a person's risk of death from cardiovascular disease, but it also provides information to physicians as they make treatment decisions, according to a report in the Journal of the American College of Cardiology. Patients whose heart rates remain elevated after exercise testing are more than twice as likely to die within six years, making heart rate recovery a risk factor comparable to, and independent of, the severity of coronary artery disease as measured by angiography. Angiography, also called arteriogram or angiogram, is an invasive procedure in which a catheter is placed in the coronary arteries, allowing physicians to determine if any arteries are blocked. The stress test is a good gauge independent of angiography, says study author Dr. Michael S. Lauer, a cardiologist with the Cleveland Clinic Foundation. "If anything, heart rate recovery is a stronger predictor of risk than the severity of coronary disease,” Dr. Lauer says. “It is also a very good predictor of people at low risk who do not need aggressive treatment.” Dr. Lauer and his colleagues collected data on 2,935 patients suspected of having heart disease. The patients underwent exercise testing followed by an angiogram. During exercise testing, patients walk on a treadmill while their heart rate and blood pressure are measured. During the test, the degree of difficulty is steadily increased as the incline of the treadmill is raised. Speed is also increased until the patient is out of breath or until the heart rate reaches a predetermined level. The object of the test is to see how well the patient's heart performs under stress. The test has been used for years to uncover heart disease. In this six-year study, 336 (11 percent) patients died. The researchers found that heart rate recovery was a stronger predictor of risk than the severity of coronary disease. Measuring heart rate recovery is different from just looking at heart disease, Dr. Lauer says. Measuring heart rate recovery is assessing autonomic nervous system function, which is different from how much blockage there is in a coronary artery, Dr. Lauer notes. He adds this is what makes heart rate recovery an independent predictor of death. Identifying People With Low RiskThe most important aspect of this finding, Dr. Lauer says, is that exercise testing can be used to identify patients who are at low risk for heart disease. "Using exercise testing to identify those at low risk for heart disease is a cheap, effective way to identify those who do not need aggressive treatment," Dr. Lauer says. Normal heart rate recovery, along with preserved functional capacity, can identify patients at low risk. Given this finding, "patients can be assured that exercise is an adequate tool for assessing heart disease," Dr. Lauer adds. Dr. Lauer says there are still many unanswered questions about the causes and mechanisms of abnormal heart rate recovery. Dr. Lauer warns individuals against trying to interpret their own heart rate recovery after routine exercise. “The problems with people taking their own heart rates are, one, we use a standard protocol which is truly symptom-limited, very different from what people do at the gym,” Dr. Lauer says. “And, two, we measure heart rates very accurately using an electrocardiogram machine. Hence we can’t simply extrapolate our findings to casual heart rate measurements in people doing typical exercise.” Experts Say Continued Study NeededHowever, Dr. Bernard Chaitman, director of cardiovascular research at St. Louis University School of Medicine and author of an editorial in the same journal, says that the implications of abnormal heart rate recovery are unclear. He says the new report contributes to new information demonstrating lower long-term survival rates in patients with abnormal heart rate responses during or immediately following an exercise test. "If we knew why people had abnormal heart rate responses to exercise, then maybe we could develop treatments to reduce the mortality rate," Dr. Chaitman adds. "Right now we don't know if treating them in any special way will reduce the mortality rate." Dr. Chaitman also does not believe that having normal heart rate recovery alone is necessarily a sign of reduced cardiac risk. Risk needs to be determined in the context of their pretest risk factors as well as the results of their exercise test, he argues. Dr. Chaitman advises that "if your heart rate responses to exercise are abnormal, you should want to know more as to why and what it means, and you should consult your physician." Always consult your physician for more information. Online Resources(Our Organization is not responsible for the content of Internet sites.) American College of Cardiology Centers for Disease Control and Prevention (CDC) National Heart, Lung, and Blood Institute (NHLBI) |
For more information on health and wellness, please visit health information modules on this Web site. What Is Coronary Heart Disease?Coronary heart disease (CHD) is characterized by the accumulation of fatty deposits along the innermost layer of the coronary arteries. The fatty deposits may develop in childhood and continue to thicken and enlarge throughout the life span. This thickening, called atherosclerosis, narrows the arteries and can decrease or block the flow of blood to the heart. Over 12 million Americans suffer from coronary heart disease - the number one killer of both men and women in the US. Risk factors for CHD often include:
Controlling risk factors is the key to preventing illness and death from CHD. Symptoms of coronary heart disease will depend on the severity of the disease. Some persons with CHD have no symptoms, some have episodes of mild chest pain, and some have more severe chest pain. If too little oxygenated blood reaches the heart, a person will experience chest pain called angina. When the blood supply is completely cut off, the result is a heart attack, and the heart muscle may be damaged. Some persons may have a heart attack and never present any symptoms. This is called a "silent" heart attack. When symptoms are present, each person may experience them differently. Symptoms of coronary heart disease may include:
To diagnose coronary heart disease, a physician will complete medical history and physical examination, and then select from a group of diagnostic procedures for coronary heart disease including:
Always consult your physician for a diagnosis. |
