Value and limitations of electrophysical testing for syncope.

Syncope is by definition a transient event, and its cause has usually resolved by the time the patient is examined. Electrophysiologic testing provides a method for assessing a patient's risk for future arrhythmias based on the known sensitivity and specificity of the analyses of sinus node function, atrioventricular conduction, and responses to programmed atrial and ventricular stimulation. Interpretation of these data must always be made in the context of the patient's total clinical situation.