In Spain there are 30,000 sudden deaths per year. Many of them could be avoided by performing a stress test to all people who start any sport practice.
What is the stress test?
The stress test or ergometry is the performance of an intense and fast physical exercise, carried out on a treadmill or static bicycle, while the electrocardiogram and blood pressure are continuously monitored.
It is a diagnostic test performed to detect various cardiac processes, especially angina pectoris, in patients with chest pain of unclear cause. The stress test attempts to reproduce chest pain by subjecting the heart to intense physical stress, while looking for electrocardiographic alterations that may have been absent at rest.
In addition to assisting in the correct diagnosis, the stress test is useful for assessing the prognosis in patients with known coronary artery disease, as well as for evaluating the effect of treatment. It can also be used to determine the appropriate level of physical exertion for each individual.
Applications of exercise testing
Ergometry tends to reproduce the greatest possible effort, even reaching the threshold of fatigue or the maximum level of endurance. During the test, the physician continuously monitors the patient’s cardiovascular parameters and informs the patient of any symptoms he/she may experience, such as chest pain, dizziness, palpitations, headache, excessive dyspnea or extreme fatigue.
It is very important that as much effort as possible is attempted for the results to be reliable. The effort depends on pre-established values according to gender, age and body mass index. Based on this, a pre-established heart rate is calculated by subtracting 220 minus age. When 85% of the referred heart rate is achieved, the test can be considered completed and valid.
The stress test has multiple applications ranging from the early diagnosis of coronary disease, to know its evolution and the response to certain treatments. It also provides detailed information on the progress of patients in cardiac rehabilitation, detection of possible hidden arrhythmias or transient heart block. It is a test that indicates the level of adaptation to effort in both professional and amateur athletes.
Preparation for the stress test
The patient should wear light clothing and comfortable shoes, preferably sneakers. In order to avoid hypoglycemia, exercise testing should not be performed after a meal (2-3 hours) or after prolonged fasting.
The patient is connected to a monitor on which the electrocardiogram is displayed in real time and continuously under the strict supervision of a physician. Exercise is started gently, on a treadmill or static cycloergometer. Every two to three minutes the level of effort is increased according to a standard schedule, increasing the speed of the treadmill and its slope, so that the heart is accelerated to a predetermined maximum heart rate that varies according to age and gender. Blood pressure is also monitored every two to three minutes.
The test is stopped when the target is reached (85% of the predicted maximum heart rate), or earlier, if symptoms and signs such as chest pain, excessive tiredness, arrhythmias, blockages, blood pressure alterations, etc. appear.
Risks of the stress test
Despite the proper selection of the technique and its correct performance, undesirable effects and some complications may occur. The risks of the stress test are minimal and rare, and include dizziness, falls, heartbeat irregularities, etc. Only if there is a serious heart disease could there be a risk of severe arrhythmias, fainting, severe chest pain or other symptoms. According to experts in Cardiology, exceptionally some cases of cardiac arrest are reported, which usually recover with the usual resuscitation maneuvers.