Arrhythmias, by their very nature, are unpredictable and intermittent, which makes it unlikely that an ECG or electrocardiogram will capture the underlying electrical pathway problem. Even tests that stretch over longer time lengths, such as Holter monitoring, may not capture an event. During an EP study, a specially trained cardiac specialist may provoke arrhythmia events and collect data about the flow of electricity during actual events. As a result, EP studies can help locate the specific areas of heart tissue that give rise to the abnormal electrical impulses that cause arrhythmias. This detailed electrical flow information provides valuable diagnostic and, therefore, treatment information. EP studies most often are recommended for patients with symptoms indicative of heart rhythm disorders or for people who may be at risk for sudden cardiac death.