Intermittent Rhythm Capture
Event Recorder
An event recorder is a form of ambulatory heart-rhythm monitoring used to capture rhythm information over a longer period, when symptoms or rhythm disturbances may not occur every day.
On this page
Understanding the test
What Is an Event Recorder?
Portable rhythm-monitoring concept
An event recorder is a type of ambulatory ECG or rhythm monitoring. It is designed to capture heart-rhythm information over a longer observation period.
It is most often considered when symptoms are less frequent, so that a short recording could miss them.
Event recorders vary. Not every device records or works in the same way, and there is no single monitoring duration that applies to all.
The reason for the test
Why Longer Monitoring May Help
A standard ECG records a short moment, and a Holter records for a defined period. If symptoms do not happen during that window, the recording may look normal even though a rhythm problem exists.
Monitoring over a longer time gives more chance to capture the rhythm when symptoms occur.
An event recorder is not always the next test. Your doctor decides what is useful in your situation.
The process
How Recording Works
The details differ between devices, but the general sequence is similar.
Rhythm monitoring
A portable or wearable device monitors the heart rhythm.
Event captured
A rhythm event is recorded, depending on how the device works.
Recording stored
The recording is stored on the device or transmitted.
Clinical interpretation
A doctor reviews the recording.
Conceptual process. Device behaviour varies.
Symptom-triggered capture
Patient-Activated Recordings
Some devices allow you to mark or capture an event when you notice symptoms, for example by pressing a button.
This helps to record the rhythm at the moment you feel the symptom.
Not every recorder has this function. You will be told what your device does and how to use it.
Automatic capture
Automatic Detection
Conceptual illustration of automatic rhythm detection
Some monitoring systems can detect predefined rhythm events automatically and record them without any action from you.
This can be helpful when a rhythm disturbance happens without symptoms or is too brief to notice.
Functions differ between devices. Not all event recorders include automatic detection.
Putting it together
Symptom and Rhythm Correlation
The key question is whether your symptoms match a rhythm change.
Symptom occurs
You notice a symptom and, where the device allows, mark it.
Rhythm recorded
The device holds the rhythm from around that time.
Timing compared
The symptom time is compared with the recording.
Doctor interprets
The finding is interpreted together with your history.
Comparison
Event Recorder vs Holter Monitoring
The two serve different purposes. Neither is better than the other.
Defined period
Holter Monitoring
Continuous recording during a defined monitoring period.
Useful when symptoms or extra beats are frequent enough to appear within that period.
Event-oriented
Event Recorder
Longer-term or event-oriented rhythm capture, depending on the device type.
Useful when symptoms are infrequent and a short recording could miss them.
Interpretation
What the Results Can Show
After the monitoring period the recordings are reviewed. They may show:
- The rhythm during symptoms
- Fast rhythms (tachyarrhythmia)
- Slow rhythms (bradyarrhythmia)
- Extra beats
- Rhythm trends and recorded events
A normal recording during symptoms can also be useful information.
The findings are interpreted in context and may guide further tests or treatment.
Clinical use
When It May Be Considered
An event recorder may be considered in situations such as:
Intermittent palpitations
Symptoms that come and go and are not captured on a short recording.
Suspected infrequent arrhythmias
Rhythm problems that happen rarely.
Symptoms missed by shorter monitoring
Where an ECG or Holter did not capture an event.
Rhythm and symptom correlation
Where the aim is to see whether symptoms match the rhythm.
Whether it is appropriate depends on your symptoms and your doctor’s assessment.
Longer-term monitoring
External and Implantable Loop Recorders
External event recorder
A portable device worn or carried for days to weeks. You press a button when symptoms occur, and many devices can also detect some rhythms automatically and store a short period before the press.
External loop recorder
A device, often worn on the skin, that records continuously and keeps the recording around an event. It suits symptoms that occur too rarely for a Holter but within a few weeks.
Implantable loop recorder (ILR)
A very small device placed under the skin of the chest in a short procedure, usually under local anaesthetic. It monitors the rhythm continuously for a long period, sometimes years, and records episodes automatically or when you activate it.
When longer-term monitoring may be useful
When symptoms such as palpitations or fainting are infrequent, when earlier monitoring has not explained them, or when a rhythm such as atrial fibrillation is suspected and needs to be looked for over time.
How the options differ
The main differences are how long the device records, whether it needs a procedure, whether it can detect events automatically and how easily it is worn. The choice depends on how often symptoms occur and on what the doctor needs to find out. See Holter Monitoring for shorter continuous recording.
Questions