Hi friend, Welcome to Health Care Magic THE FIRST STEP IS TO SEE A CARDIOLOGIST Routine 12-lead Electrocardiogram (ECG) is part of clinical examination. If a routine ECG does not show, 24 to 48 hour ambulatory monitoring (Holter) is done to analyse and plan for further management ECHOcardiogram is necessary to see the heart valves (Mitral Valve Prolapse) / heart muscle (Cardiomyopathy) and heart function (Ejection fraction, wall motion abnormality). Treadmill exercise ECG (TMT) is done to exclude Ischemia (reduced blood flow). Laboratory work-up is routine - like blood counts, sugar, urea, electrolytes (potassium in particular), thyroid (over-active) and so on. Your Internist shall suggest based on the situation. If there are no clues and if you are still bothered by it to the extent of interfering with life style, there are more tests. The treating doctor may suggest them depending on need, based on his assessment of the situation. They are advanced techniques of investigations of increasing complexity (and invasive) – like Electro Physiological Stdies (EPS) it resembles angio / a catheter is put inside the heart, electrical activity recorded, stimulation and suppression tests are carried out, suitable medicine tested and so on. Though the test is the gold standard, it is invasive and has a minimal risk and is not generally done unless there are compelling indications. This super-speciality expert is called ELECTRO-PHYSIOLOGIST. Take care Wishing speedy recovery God bless Good luck