Background: Syncope is a common clinical problem which can be remarkably debilitating and associated with high health care costs. Syncope is a clinical syndrome with many potential causes. The aim of the study was to determine the etiologies of patients with syncope in the emergency department (ED) of a referral and general university hospital.

 Methods: One hundred sixty-five consecutive patients aged more than 18 years old with syncope were admitted to the emergency department of Ayatollah Rouhani Hospital. Initially organized, systematic approach included detailed medical history and structured questionnaires for history taking, physical examination, ECG and cardiac monitoring, cardiology and neurology were done. Advanced diagnostic tests were carried out if the etiology of syncope remained unexplained.

 Results: Out of the 165 patients who presented to the ED between February 2012 and February 2013, 124 had definition of syncope. The mean age of male patients was 59.5±19.8, 58. The etiology of syncope was diagnosed in 104 (83%) patients. Neurocardiogenic syncope was found in 36 (29.03%) patients, cardiac arrhythmias in 40 (32.25%) patients, and acute coronary syndrome in 8 (6.45%) patients. There are some infrequent etiologies like intracranial hemorrhage in 5 patients, aortic stenosis in 4 patients, hypertrophic cardiomyopathy and aortic dissection in 3 patients, Brugada and pulmonary embolism in 2 patients and carotid hypersensitivity in one patient.

 Conclusion: We found that cardiac arrhythmias and neurocardiogenic type are the frequent causes of syncope. In about one-sixth of the patients, no etiology was found. Approximately one-third of patients had traumatic syncope.