Hi there. The best test is an angiogram. Its an invasive test, but basically a tiny line is inserted in an artery in the groin or wrist. The doctor threads this to your heart, a contrast dye is released which shows on the monitor for the doctor to view. (Its like a moving live Xray) Blockages are generally spotted promptly with this test. The test result can be clear or if there is CAD, the doctor will discuss options including Bypass or more often Stent placement. If there is a blockage of less than 70%, intervention is unlikely, but medication treatment is likely.
This test is good for measuring heart function also, as well as looking at valves. An echo can also be done, this is useful as a test to look at the heart function side of things.The echo is an ultrasound test and is non invasive, but for checking for blockages, the Angio is best. For checking electrical activity of your heart, an ECG test is often carried out. This is often the initial test done.