What is a Holter Monitor? A Holter monitor is a small, wearable device that records heartbeats. It's used to determine whether you're at risk of developing an irregular heartbeat (arrhythmias).

A Holter monitor test may be used if a regular Electrocardiogram (ECG or EKG) does not provide enough information about the heart's condition. If the irregular heartbeats are infrequent, a longer-term monitor, such as an event recorder, may be required.