Heart disease is diagnosed through a wide variety of different tests. As a first step, your doctor will take your medical history, record your current and past symptoms, perform laboratory tests, and perform an electrocardiogram. Further tests may be ordered by your doctor based on the results of your assessment and tests. It is possible to perform some of these tests non-invasively, which means no instruments are inserted into the body. There are also invasive tests that require instruments to be inserted into the body.