Diagnostic value of history taking in reflex syncope.

The medical history, in combination with the physical examination and a 12-lead electrocardiogram, plays a key role in the diagnosis and risk stratification of patients with syncope. However, diagnostic clinical criteria are not uniformly applied. In older studies, the diagnostic criteria for vasovagal or reflex syncope often included typical precipitating events and warning symptoms. More recent studies have documented that a variety of unrecognized stressors can trigger reflex syncope and that warning signs and symptoms may be minimal. A characteristic medical history (a trigger and/or prodromi) is enough to diagnose reflex syncope if the risk for a cardiac cause of syncope is low (e. g. patients < 65 yrs, without a history of heart disease and no ECG abnormalities). In elderly subjects with a higher risk of cardiac syncope, the yield of the medical history is lower. However, a prospective study of the value of the medical history for the diagnosis of syncope with long-term follow-up has not been performed.