A cardiac event monitor is a portable medical device used to record the heart’s electrical activity (electrocardiogram or ECG) over an extended period, typically ranging from several days to a few weeks. Unlike a standard ECG, which captures a snapshot of heart activity during a short clinical test, an event monitor is designed to capture intermittent or infrequent cardiac symptoms that may not be detected during a routine exam. This device is particularly useful for diagnosing arrhythmias (abnormal heart rhythms), unexplained fainting (syncope), palpitations, or episodes of dizziness.
Cardiac event monitors are typically worn by patients who experience symptoms that occur sporadically. There are two main types of event monitors: looping memory monitors and post-event monitors. Looping memory monitors continuously record and overwrite heart rhythms, saving data when the patient activates the device in response to symptoms. Some can also auto-activate based on preset heart rate thresholds. Post-event monitors, on the other hand, begin recording only when manually activated. This means they rely on the patient to recognize symptoms and initiate a recording.
The device usually consists of small electrodes attached to the chest and connected by wires to a recorder, which is often worn on a belt or carried in a pocket. In some models, the monitor is wireless and patches directly onto the skin. Patients are instructed to press a button on the device when they feel symptoms such as chest pain, fluttering, lightheadedness, or fainting. When activated, the monitor saves the heart’s rhythm before, during, and after the episode.
Some event monitors allow real-time data transmission to a monitoring center via a phone or internet connection. This enables healthcare providers to review the ECG shortly after the event and make timely decisions about further diagnostic steps or treatment. In contrast, traditional models store the data internally and require the patient to return the device for analysis after the monitoring period ends.
The advantages of cardiac event monitoring include its non-invasive nature, ease of use, and ability to capture transient events that would otherwise go undetected. It plays a vital role in diagnosing arrhythmias such as atrial fibrillation, supraventricular tachycardia, or pauses in heart rhythm (asystole). Once a diagnosis is made, appropriate interventions such as medication adjustments, pacemaker implantation, or lifestyle changes can be considered.