The purpose of the study is to investigate effect of medical treatment and prognosis of Postural Orthostatic Tachycardia Syndrome (POTS)

Many patients who complained of dizziness are eventually diagnosed as POTS. However, the investigation of an appropriate medical treatment of POTS has not been enough yet. Also, the prognosis of the disease after treatment is not well known. It is known that propranolol attenuate the tachycardia and improve symptom burden in patients with POTS. However, the effect of other β-Blocker, bisoprolol compared with propranolol is not known well. In addition, acetylcholinesterase inhibition with pyridostigmine was a effective method of acutely decreasing the tachycardia in patients with POTS. However, difference among three medical treatments effect is not known and long-term studies are not done yet. Therefore, in this study investigator investigate effect of medical treatment (propranolol only, bisoprolol only, propranolol+pyridostigmine, bisoprolol+pyridostigmine) and prognosis of Postural Orthostatic Tachycardia Syndrome.

Longer-term studies are needed to assess this promising therapy.

Inclusion Criteria:

• aged 15<=
• developed symptoms of orthostatic intolerance accompanied by a HR rise ≥30 min-1 within the first 10 minutes of standing, HR rise ≥ 120 in the absence of orthostatic hypotension (a fall in blood pressure [BP] >20/10 mm Hg).

Exclusion Criteria:

• poor drug compliance
• patients who cannot or do not want to write questionaires.
• patients who do not want draw blood