Hi
A thorough history and physical examination is the first step -
Irregular heart beats need to be documented by ElectroCardioGram (ECG / EKG).
If a routine ECG does not show, 24 or 48 hour ambulatory ECG monitoring (Holter) is done.
An
ECHOcardiogram is done to see the heart valves, wall and function
Some laboratory work-up also is routine - like blood counts, sugar urea, electrolytes,
thyroid - depending on the situation
There are several more (some of them invasive) - depending on these results and severity.
Smoking is an important cause in many / some have bypass tracts (additional pathways/
nerve fibres) in the heart / so on
Beta blockers are generally started / there are several drugs - acting by different mechanisms - the specialist will decide tailored to the individual
Take care
Good luck