The use of monitoring strategies in patients with unexplained syncope--role of the external and implantable loop recorder.

Syncope is a complex clinical syndrome with multiple etiologies that can be very difficult to diagnose. The major obstacles to diagnosis are the periodic and unpredictable nature of events and the high spontaneous remission rate. Short-term electrocardiographic monitoring is often unproductive in patients when initial non-invasive testing is negative, particularly when a paroxysmal arrhythmia is suspected. The external and implantable loop recorders extend the ability to monitor cardiac patients, enhancing the diagnostic yield to as high as 85% in difficult to diagnose syncope. Several recent studies suggest that prolonged monitoring with an implantable loop recorder has a role in patients with syncope and conduction disturbances, negative tilt testing, unexplained seizures and may be superior to conventional testing with tilt and electrophysiologic studies in selected patients.