Diagnostic Tests in Syncope: 5A Diagnostic Tests in Syncope: Tilt-Table Testing, Autonomic Tests, and Electrophysiological Study

Transient loss of consciousness (TLOC) is a common presenting complaint with a wide range of possible causes including syncope, seizures, concussion, and metabolic disturbances. In the initial evaluation, a crucial step is determining whether the patient’s symptoms are due to syncope. Careful history taking, standing BP and an ECG will establish a reasonably certain diagnosis in most patients, and if the initial evaluation provides a clear diagnosis subsequent testing can be avoided. However, if further assessment is needed, then selective diagnostic testing is warranted. Given the frequency of vasovagal and other reflex syncope forms, autonomic evaluation including tilt-table testing may be useful. Tilt testing and active standing tests may also help assess susceptibility to orthostatic hypotension (OH). Carotid sinus massage may be useful in older patients but must be interpreted with caution as carotid sinus hypersensitivity is common and often unrelated to the cause of syncope. Electrophysiological study has only a limited role in syncope diagnosis but may be considered in patients with underlying structural heart disease or ECG evidence of significant conduction system disease. Extended ambulatory monitoring, particularly with an implantable cardic monitor (ICM), has been shown to be safe and cost-effective and recommended early in the evaluation process.