Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Emergency symptoms remain different from routine follow-up concerns.
Seek immediate help for fainting, severe shortness of breath, persistent chest pain or pressure, stroke symptoms, or collapse with abnormal breathing.
Contact the treating clinician promptly if episodes become more frequent or prolonged, symptoms change, or a medicine appears to cause side effects.
People taking an anticoagulant should report unusual bleeding and follow instructions for procedures, injuries, and missed doses.
Follow-up depends on the diagnosis and treatment.
Routine visits may be used to review symptoms, check heart rate and blood pressure, assess medicine side effects, and repeat rhythm monitoring.
People with a pacemaker or ICD need scheduled device checks.
The article also says
Keep a current list of medicines and supplements.
A symptom log can record the time of an episode, its duration, activity at the time, and associated dizziness, chest discomfort, or breathing difficulty.
Bring recordings from a wearable device if available.
Every sign above is quoted from the sofidex article on Arrhythmias. If you are not sure, err upward — it is always reasonable to be checked.