Heart Health

Holter/Event Monitor

What is a Holter Monitor?

A Holter monitor is a portable electrocardiogram (ECG) that measures your heart’s electrical current for a period of time varying from 24 hours to 72 hours. This type of test is primarily performed if a standard ECG cannot detect irregularities in the heart’s electrical activity.

What is a Cardiac Event Monitor?

A cardiac event monitor is also a type of portable ECG that is similar to a Holter monitor. It records that same information as a Holter monitor, but not continuously. There are two types of event monitors: symptom event monitors and looping memory monitors. 

A symptom event monitor is only activated when the user becomes symptomatic. It can record information for a few minutes following the activation of the device. This information is then relayed to your doctor by phone or Internet depending on the type of device.

A looping memory monitor does the same thing, but it can also record the data from the minutes leading up to the symptomatic episode.  Both event monitor options are used for long-term testing and can be worn for up to 30 days.

Your doctor may suggest Holter or event monitor testing if you are experiencing the following symptoms:

  • Unexplained fainting, dizziness or lightheadedness
  • Heart palpitations
  • Chest pains
  • Irregular heartbeat


A Holter or event monitor may also be suggested to:

  • Evaluate the success of a pacemaker
  • Evaluate how well the treatment of a complex arrhythmia is working

What Happens During a Holter or Event Monitor Test?

The test is performed by placing electrodes (small, plastic patches that adhere to the skin) in standardized locations. The electrodes are then connected to a portable monitoring device that attaches at the site of the electrodes. You will be asked to keep a diary or the events you perform while wearing the monitor. The monitor will be returned to your doctor after the test is complete.

What are the Risks of Having a Holter or Event Monitor?

There is no pain or risk associated with having a Holter monitor or an event monitor. Some patients may experience skin irritation from the adhesive on the electrodes or minor discomfort when then the electrodes are removed from the skin.

Request an Appointment

To learn more about Holter monitors, event monitors, or other heart monitoring exams,  request an appointment with your doctor today!