Hello, The thallium stress test is done to see whether your heart muscle is getting enough blood flow, and therefore enough oxygen, when it is working hard (under stress). It is being done in you so as to see... How well your heart is pumping Diagnose the coronary artery disease To determine the proper treatment for coronary heart disease. A normal result means that blood flow through the coronary arteries is probably normal. An abnormal result indicates that there is reduced blood flow to a part of heart muscle most likely due to blockage or narrowing of one or more arteries that supply your heart muscle. After the test it is decided whether to go for Angioplasty or CABG. Thanks