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 monitor ing is non-diagnostic in 90 % of cases. Recent developments in loop recorde r technology permit longterm ECG monitoring in patients with recurrent unex plained syncope. The implantable loop recorder monitors a single lead elect rogram continuously using 2 sensing electrodes on the device shell. The dev ice was implanted in 20 patients (11 male, 9 female) with the history of re current syncope. During a mean follow-up of 12 +/- 6 months after device im plantation, 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 d etermined whether an arrhythmia was the cause of symptoms or not. Diagnosis included bradycardia in one patient, tachycardia in two patients, in one p atient two rhythm disturbances were revealed: frequent ventricular prematur e beats with bigemini and atrial flutter. Two patients had a neurocardiogen ic syncope. Syncope was nonarrhythmic in 5 patients. An implantable loop re corder is useful for establishing the diagnosis if symptoms are recurrent b ut too infrequent for conventional monitoring techniques.