Initial experience with an implantable loop recorder in patients with unexplained syncope

Patients with recurrent syncope undiagnosed after extensive noninvasive and invasive testing pose a diagnostic and therapeutic dilemma. Holter monitoring is non-diagnostic in 90% of cases. Recent developments in loop recorder technology permit longterm ECG monitoring in patients with recurrent unexplained syncope. The implantable loop recorder monitors a single lead electrogram continuously using 2 sensing electrodes on the device shell. The device was implanted in 20 patients (11 male, 9 female) with the history of recurrent syncope. During a mean follow-up of 12+/-6 months after device implantation, 11 patients (55%) experienced syncope (8 pts) or presyncope (3 pts). In the remaining 9 patients, no syncope occurred. In all 11 patients with syncope or presyncope during follow-up, loop recording definitively determined whether an arrhythmia was the cause of symptoms or not. Diagnosis included bradycardia in one patient, tachycardia in two patients, in one patient two rhythm disturbances were revealed: frequent ventricular premature beats with bigemini and atrial flutter. Two patients had a neurocardiogenic syncope. Syncope was nonarrhythmic in 5 patients. An implantable loop recorder is useful for establishing the diagnosis if symptoms are recurrent but too infrequent for conventional monitoring techniques.