An electrocardiogram, also known as an ECG or EKG, is a diagnostic test used to check for different heart conditions. The test is performed by placing electrodes or small adhesive pads on the body and around the chest to record the electrical signal from the heart. EKG testing can be used to screen and diagnose cardiac-related medical conditions. This test is often performed with an annual physical exam or as a part of a screening exam to make sure there are no underlying abnormalities with the heart that need further medical evaluation or work-up.