Also known as ECG or EKG. An electrocardiogram, also called an ECG or EKG, is a simple, painless test that detects and records your heart’s electrical activity. An EKG can show how fast your heart is beating, whether the rhythm of your heartbeats is steady or irregular, and the strength and timing of the electrical impulses passing through each part of your heart. You may have an EKG as part of a routine exam to screen for heart disease.