My husband and father both had quadruple bypasses during the summer of 2005. Both were given EKG's and Echo's and both showed some abnormality. My dad was given a stress test, and as I recall, it was the Isotope Stress Test (or IST). This test includes imaging before the stress test, then the stress test itself (treadmill), then imaging after the stress test. For the "after" imaging, a nuclear isotope is injected and the imaging machine takes 3-D images of the heart. The dye shows where blood flow is slowed or stopped by plaque. They found Dad's blockages this way. For my husband, however, the doctor said that based on how he "looked", and on the EKG and Echo, he wasn't going to put him through a stress test because "I know you'll fail it". He sent my husband straight to the hospital, where they did the angiogram. This is how they found his blockages. As others here have stated, the EKG, Echo, and stress tests can't tell a doctor difinitively that there are blocked arteries and/or veins, but abnormal readings can indicate a possible problem. From these readings the doctor can then determine the next testing to be done in order to pinpoint the exact problem. In these two men, one was diagnosed with the IST, the other with the angiogram. For more info, you can check out these sites: Angiogram: http://www.vascularweb.org/_CONTRIBUTION_PAGES/Patient_Information/NorthPoint/Angiogram.html IST: http://www.heartsite.com/html/isotope_stress.html It's amazing how educated one becomes when a family member is diagnosed with a health issue. Between cancer (5 fam members), artherosclerosis (3 fam members, all had quad-bypasses, all in 2005), Multiple Sclerosis, and Diabetes, I now seem to know more about these issues than I ever thought I would! Best wishes!