Prospective evaluation of syncope.

One hundred seventy patients with syncope presenting to an emergency department were studied prospectively. A checklist was used to supplement the physician's history and physical to ensure adequate recording of potentially useful data. Follow-up data were available in 89% of patients with a mean follow-up period of 6.2 months. Patients were categorized by presumed etiology using specific criteria. Typical vasovagal syncope occurred in 37.1% of patients. Other etiologies included first seizure (8.8%), orthostasis (7.6%), cardiac (4.1%), micturition (2.4%), hypoglycemia (1.8%), and psychogenic (0.6%). Syncope of unknown etiology accounted for 37.6% of the patients. The estimated duration of warning period was significantly shorter in patients with cardiac syncope compared to patients with vasovagal syncope. The yield of laboratory tests was low with the exception of the serum bicarbonate, which was decreased in 70% of our seizure patients. Recommendations regarding initial evaluation and admission are discussed.