Holter and event monitors are small, wearable devices that record your heart rhythm. You usually wear a Holter monitor for one to three days and event monitor up to 30 days. During that time, the device will record all of your heartbeats. A Holter or event monitor test is usually performed after a traditional test to check your heart rhythm (electrocardiogram) isn't able to give your doctor enough information about your heart's condition.
A Holter and event monitor has electrodes that are attached to your chest with adhesive and then are connected to a recording device. Your doctor uses information captured on the monitor's recording device to figure out if you have a heart rhythm problem.
Although similar, Holter and event monitors aren't the same. A Holter monitor records your heart's electrical activity the entire time you're wearing it. An event monitor only records your heart's electrical activity at certain times while you're wearing it.
While wearing these monitors may be a little inconvenient, it's an important test that may help your doctor diagnose your condition.