You can wear a Post-Event recorder or carry it in your pocket. The pocket version is about the size of a thick credit card. These monitors don't have wires that connect the device to chest sensors. To start the recorder when you feel a symptom, you hold it to your chest. A Post-Event recorder only records what happens after you start it. It may miss a heart rhythm problem that occurs before and during the onset of symptoms.
Caution: U.S. Federal law restricts this device to sale by or on the order of a physician.