Treadmill Stress Testing

Treadmill stress testing is a fundamental office based procedure in cardiology. Patients with symptoms of chest pain are the most appropriate candidates for treadmill testing. The diagnostic accuracy of a stress test is related to the pre-test probability of significant disease. It would be pointless to send a patient for a stress test if they report severe symptoms that are typical in nature at rest or with minimal effort.

Classic symptoms of cardiac chest pain include exercise induced pain or pressure, jaw pain, pain radiating to the left arm and chest pain with shortness of breath. Patients with high probability for a significantly abnormal test include diabetics, patients with kidney disease, patients with peripheral arterial disease and patients with known history of heart disease.

Conversely, if a patient has symptoms that are clearly not cardiac in origin and has very low risk of disease (no hypertension, no diabetes and less than 40 years old) there is often no need for a treadmill test. The conventional wisdom is to order a treadmill test for a patient with a 50 percent probability of having significant disease. The clinician must consider the possibility that if the test is positive, in a truly low probability patient, he may not believe it. If it is negative in a very high probability patient, she may not believe that, either. For this reason, you should not order a stress test for diagnostic purposes on patients on the extremes of the risk categories. An appropriate use of a stress test in a high probability patient would be to determine the effectiveness of medical therapy.

The standard treadmill test itself requires walking at three-minute intervals at increasing speeds. The longer the patient walks, the better. At each stage of exercise, an electrocardiogram is obtained to evaluate for depression in the baseline tracing. This depression in the tracing represents ischemia or low blood flow. The deeper the depression and the more areas affected, the worse the prognosis. If symptoms are present with abnormalities on the ECG; there is high probability that clinically significant obstructions are present in the coronary arteries.

If a patient can't walk, testing can be performed with nuclear perfusion scanning or echocardiography. Abnormal results on stress testing can be seen in patients with an enlarged heart or with excessively high blood pressure. If the test is a "true positive" treatment with beta-blockers, aspirin, statins and nitrates are usually started and consideration for cardiac catheterization should be entertained.