Unexplained syncope: What to expect from loop recorders

The specific etiology of syncope can sometimes be pinpointed by transtelephonic ambulatory monitoring with looping memory capability. Utilizing a database (Raytel Cardiac Service, Inc.) we have isolated 361 incidents of syncope in 268 patients. The mean age of the patients was 44.1 years and 57% were female. Methods: Patients were supplied with an event recorder monitor for a 30 day period. Electrocardiogram recordings captured during or just subsequent to symptomatic events were transmitted by telephone. Cases recorded for a twelve month period were examined for the occurrence of syncope. Results: Episodes of arrhythmias were confirmed for 49 (18.3%) patients in the group studied. Eighty-two arrhythmias were documented in association with syncope. Of these arrhythmias, 58 (70.7%) were bradycardia and 24 (29.3%) were tachycardias. The recorded arrhythmias which correlated with syncope were junctional rhythm (23), supraventricular tachycardia (17), sinus node dysfunction (16), asystole (10), heart block (9), and ventricular tachycardia (7). Conclusions: (1) Event recorder monitors with loop recording capability documented arrhythmias in 23% (82/361) of the symptomatic syncopal events. (2) Bradyarrhythmias are the most common arrhythmias associated with syncope in these patients.