People who may have arrhythmias need to receive a thorough cardiac examination, which may include one or more of the following tests:  

History and physical examination
The first steps the doctor will take.

Electrocardiogram (ECG or EKG)
A test in which several electronic sensors are placed on the body to monitor electrical activity associated with the heartbeat.

Signal-averaged ECG
A more detailed type of ECG during which multiple ECG tracings are obtained over approximately 20 minutes to capture abnormal heartbeats that may occur intermittently.  A computer captures electrical signals from the heart and averages them to provide the physician more detail about the heart's electrical conduction system is working.

Electrophysiology (EP)
Electrophysiology (EP) is a cardiac specialty that tests electrical activities in the heart to find the cause of your heart rhythm abnormalities—irregular heartbeats or abnormalities that cause the heart to beat too quickly, too slowly, or irregularly— and determine the best treatment for you.

To find the cause of your heart rhythm disturbance, physicians will insert one or more small wires through a vein in the leg or upper extremity leading to the heart. Programmed electrical stimulation then reproduces your arrhythmia to determine the nature and location of the rhythm disturbance. Based on the findings, your physician may have you try different medications, or recommend a procedure or device to treat your heart rhythm.

A method of studying the heart's structure and function by analyzing sound waves bounced off the heart and recorded by an electronic sensor placed on the chest. A computer processes the information to produce a one-, two- or three-dimensional moving picture that shows how the heart and heart valves are functioning.

Exercise stress testing
A common test for diagnosing coronary artery disease, especially in patients who have symptoms of heart disease. The test helps doctors assess blood flow through coronary arteries in response to exercise, usually walking, at varied speeds and for various lengths of time on a treadmill. A stress test may include use of electrocardiography, echocardiography, and injected radioactive substances. Also called exercise test, stress test, or treadmill test.

Tilt-table evaluation 
Measures your heart rate and blood pressure while lying flat, then monitors them as the table is tilted up. Position changes exert stress on the part of the nervous system responsible for maintaining heart rate and blood pressure, so physicians can observe the cardiovascular response under controlled conditions. The evaluation, which takes 20 to 45 minutes, is helpful for patients with syncope (blackout).

Arrhythmia monitoring devices
You may be asked to wear a Holter monitor, which records your heart rate and rhythm continuously for up to 24 hours at a time. Long-term monitoring - up to a month - may be performed with an event monitor, which records an infrequent arrhythmia and provides a way for your doctor to retrieve and save the data via computer recording.