Exercise Treadmill Test

An exercise treadmill test (ETT) is an real-time evaluation of the heart while under cardiovascular stress. A primary care provider or well-trained professional performs ETTs in the outpatient setting. The testing is performed with a treadmill or bicycle and the heart's electrical activity (electrocardiogram, EKG), blood pressure, heart rate, and pain levels are measured. Individuals undergoing this exam have typically exhibited unclear chest discomfort or signs of myocardial ischemia and have significant risk factors for coronary artery disease (CAD). The ETT aims to reproduce any chest discomfort or electrical changes in the heart for an evaluation of worsening disease. ETTs are most beneficial in symptomatic men, older than 45 years old with risk factors for CAD, and are least predictive of disease in women, and individuals less than 35 years old.

Although there are numerous acceptable protocols to complete an ETT, the overall goal remains consistent. The intensity of the treadmill increases until the patient reaches approximately 85 percent of his or her predicted maximum heart rate for his or her age group. If any type of pain occurs prior to reaching this goal, the testing may be terminated early. Interpretation of ETTs involve monitoring the EKG, heart rate, and blood pressure values for changes indicative of worsening ischemia, decreased exercise capacity, or arrhythmias. Following the results, a clinician may determine that this patient is a candidate for angioplasty, a procedure involving the unblocking of the heart's coronary arteries.

ETT is relatively safe, but as myocardial infarctions occur in 1 of 2,500 tests, clinical discretion of which patients are most appropriate for testing is imperative. Patients with cardiac arrhythmias, electrical conduction blocks, a recent heart attack, or uncontrolled heart failure represent absolute contraindications. Patients who are overly obese, have difficulty walking, have significant pulmonary disease, or have central nervous system disorders may have limitations preventing testing completion; thus, other testing modalities may need to be performed. ETT can be combined with further imaging including ultrasound (echocardiography), to visualize the heart's wall motion, or with nuclear imaging to measure heart muscle perfusion.