How can I conveniently record intermittent discomfort related to arrhythmia for my doctor's visit?

After each episode of discomfort, note the time it occurred, how long it lasted, what you were doing, and exactly how it felt. Also note whether it started suddenly or gradually and how it ended. If you have a device that records data, keep the original data with timestamps for your doctor to review, but do not treat the device's readings as a diagnosis on your own. If you cannot measure anything, a written description is enough; do not delay seeking help just to get data.