Stress ECG testing is performed before and after the heart is placed under some kind of stress. This stress can occur in the form of exercise (e.g. walking on a treadmill), which forces the heart to beat faster and harder than usual. A stress ECG is typically performed if your doctor needs to know whether or not you have decreased blood flow to the heart. Decreased blood flow to the heart could indicate the presence of coronary artery disease – this occurs when cholesterol plaque accumulates inside the arteries. Symptoms of coronary heart disease include chest pain and can result in a heart attack.