Transient loss of consciousness

Transient loss of consciousness (T-LOC) is caused by cardiovascular (syncope), neurological (seizure) and psychological (non-epileptic attack disorder) conditions. Suspected cardiovascular causes should be further defined as either reflex/blood pressure regulatory or cardiac/arrhythmic disorders. Identifying select individuals at high risk of sudden death from amongst 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 taking a detailed history. Risk stratification into those at high and low risk of future cardiac arrest should be a standard part of the initial assessment of every T-LOC patient. Risk stratification is easily performed by considering the presence/absence of structural heart disease, family history of sudden unexplained death under 40 years of age and by systematic analysis of 12-lead ECG. Patients with high-risk features in whom 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.