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HowToPreventHeartDisease.com |
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Why Stress Tests Revealed Fewer Heart Blockages? Coronary heart disease (CHD) is a disease in which plaque builds up in the coronary arteries that supply oxygen-rich blood to the heart. The plaque narrows the arteries and reduces the blood flow to the heart muscle. Blood clots, which can partially or completely block the blood flow, will more likely to form in the arteries. This can then lead to angina (chest pain) or even a heart attack. When a person’s heart is at rest, he or she may not have any signs or symptoms of CHD. During exercise, however, the heart has to work harder, and it will need more blood and oxygen. Narrow arteries cannot supply enough blood for the heart and hence signs and symptoms of CHD might surface. Doctors usually use stress test or sometimes called exercise test to help diagnose and find out the severity of CHD. During test, the patient is asked to walk or run on a treadmill or pedal a stationary bike to make the heart work hard and beat fast. Tests are done on the heart while the patient exercises. For patients who have arthritis or other medical problems that refrain them from exercising during a stress test, doctor might perform an alternative test called pharmacological stress test. In such test, doctor gives the patients medicine to make their heart work hard as if it would during exercise.
Stress test could reveal problems such as abnormal changes in the heart rate or blood pressure, shortness of breath or chest pain (especially if they occur at low levels of exercise), abnormal changes in the heart’s rhythm or electrical activity. If a person cannot exercise for as long as what is considered normal for his or her age, it might indicate that insufficient blood is flowing to the heart. Nevertheless, there are other factors besides CHD that can prevent one from exercising long enough, for instance, lung disease, anemia, or poor general fitness. Approximately two thirds of patients with CHD could be diagnosed by a stress test. The accuracy is about 50 percent when patients have narrowing in a single coronary artery and higher than 80 percent when all the 3 major arteries are blocked. There will be about 10 percent of patients might have a false-positive test when the result is falsely abnormal in a patient without CHD. A paper, published on March 12, 2013 in the ‘Journal of the American College of Cardiology’, reported that the proportion of patients have blocked arteries show up during a stress test has dropped significantly over the past 20 years. In the new study, researchers from St. Luke's Roosevelt Hospital in New York City assessed 39,515 diagnostic patients who underwent stress test to locate blocked arteries at Cedars-Sinai Medical Center in Los Angeles between 1991 and 2009. During that period, the proportion of referred patients with an abnormal test fell from about 41 percent to less than 9 percent. Similarly, the proportion with moderate to severe blockage dropped from 21 percent to 5 percent. In the study's later years, more patients undergoing the test were obese or had diabetes but fewer smoked. The researchers argued that the findings might suggest fewer people with heart-related symptoms, like chest pain, have blockages, or it could mean that doctors might need a better test to diagnose these patients. Other health professionals had, however, different interpretation of the findings. They felt that the stress test has been overused. It is possible that more people with only mild or non-traditional heart disease symptoms, like shortness of breath, are being sent to stress test when it is unlikely to reveal any problems. Meanwhile, the study also found that the majority of tests performed in recent years were pharmacologic stress tests, which are typically 3 to 4 times more expensive than an exercise stress test. Clearly, this also reflects that more and more doctors are using the more expensive test for less appropriate patients.
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