Comparison between electrophysiologic studies and ambulatory monitoring in patients with syncope.

The efficacy of 24-hour ambulatory monitoring and electrophysiologic studies was determined in sixty-five patients with a history of syncope or pre-syncope. Patients with an obvious cause of syncope and/or significant arrhythmias on the resting ECG were excluded. Monitoring and electrophysiologic studies were performed within one week. Arrhythmias and/or electrophysiologic abnormalities which were considered to be the cause of syncope or pre-syncope were detected with monitoring in 31 patients and with electrophysiologic studies in 42 patients. By combining both methods symptoms were explained in 51 patients (78%). In 22 of the patients arrhythmias were detected with both methods. Thus, in a group of patients with no obvious cause of syncope, abnormalities were readily detected with monitoring and electrophysiologic studies. These methods are complimentary and should be used (monitoring usually first) in the appropriate symptomatic patient.