Patients should wear comfortable clothing that can be easily removed from the waist up. There is no need to limit eating or drinking before the electrocardiogram (EKG), and the test can be scheduled for any time of day. The test may be done in the physician’s office, a hospital or a clinic.

It is important for the physician to have a patient's complete medical history, including any medications that the patient is taking. Certain medications can affect the result of an EKG.

EKGs are noninvasive, quick, safe and painless. After removing clothing and jewelry from the waist up, the patient will be instructed to lie down. A nurse or technician will clean a series of small areas on the patient’s chest, arms and legs. The technician will apply gel to these areas. Ten or 12 small pads or metal devices (electrodes) are then attached to those clean areas of the skin and connected by wires to the electrocardiograph machine.

The electrodes record only the electricity that passes naturally through the heart. Electricity does not pass from the pads to the patient.

The technician will enter the patient’s information into a computer (e.g., name, age, sex, date). The patient will be asked to lie perfectly still for up to several minutes while resting-heart activity is measured and recorded. Each electrode produces a “tracing” or “lead” of a particular area of the heart and its activity.

Part of the evaluation may include an exercise stress test. This test requires the patient to either walk on a treadmill at varying speeds and elevations, or ride a stationary bicycle, to measure the heart’s activity during physical activity.

EKG results should be immediate. In some cases, the test may be done outside the physician’s office and results transmitted via phone line back to either the physician or another diagnostic center for evaluation. Transtelephonic monitoring, for the purpose of assessing the heart rhythm, can detect abnormal heart rhythms (arrhythmias) that occur when the patient is not in the physician’s office.

Depending upon the results, further treatment may or may not be necessary. If damage or a problem is found, usually a combination of medications and risk-reducing lifestyle changes is prescribed.

Abnormal EKG results will likely result in further testing. This may include imaging studies, such as chest x-ray, echocardiograms, magnetic resonance imaging (MRI) or computed tomography (CAT scan), or nuclear imaging studies that use specialized tracer chemicals to evaluate the heart's health. In some cases, EKGs may be combined with imaging studies, allowing the physician to carefully time the images of the heart to different phases of the heartbeat. This is called a gated study. More invasive testing, including coronary angiogram and electrophysiology studies, may also be recommended. The nature of the follow-up testing depends on what disease is suspected.

If abnormalities are not detected at the physician’s office, then the patient may be asked to wear a Holter monitor, a portable tape recorder that records the heart’s rhythm, usually over a 24-hour period.