Transient loss of consciousness

Transient loss of consciousness (T-LOC) is usually caused by cardiovascular (syncope), neurological (seizure) and psychological (non-epileptic attack disorder) conditions. Suspected cardiovascular causes should be further defined as reflex/blood pressure regulatory or cardiac/heart rhythm disorders. Identifying select individuals at high risk of sudden death from a large cohort of patients with more benign causes of T-LOC is a major challenge. The key to assessing a patient with T-LOC lies in a detailed history. Risk stratification into patients at high and low risk of future cardiac arrest should be an integral part of the initial assessment of every T-LOC patient. Risk stratification is easily performed by considering the presence or absence of structural heart disease and family history of sudden unexplained death below 40 years of age, and by systematic analysis of a 12-lead electrocardiograph. Patients with high-risk features whose T-LOC is thought to be cardiovascular in origin should be referred to a heart rhythm specialist for urgent assessment. In these cases, T-LOC is an opportunity to intervene with highly effective therapies before a cardiac arrest occurs.