Utility of implantable loop recorder (Reveal Plus) in the diagnosis of unexplained syncope

In about 30% of patients with syncope, the responsible mechanisms remain unrecognised. Nevertheless, the possibility of an arrhythmic aetiology remains, however, difficult to rule out.

We therefore monitored with an implantable loop recorder (ILR, Reveal Plus, Medtronic) 34 subjects (60+/-15 years) with at least two unexplained syncopal episodes and negative neurological and cardiovascular work-up.

During a follow-up of 7+/-4 months, syncope occurred in 11 subjects. In nine of them the mechanisms responsible for these events were identified by ILR monitoring: marked bradycardia or asystole (n=6), atrial fibrillation with wide QRS tachycardia (n=1) and sinus rhythm with fine artifacts likely to be due to muscle contractions (n=2). Pre-syncope occurred in seven patients: advanced atrioventricular block (n=3), sinus tachycardia (n=1), and wide QRS tachycardia (n=1) were documented. Thus, when considering all 18 patients with recurrences, a diagnosis was achieved in 53% of subjects. Recognition of the rhythm disorder in seven patients with syncope and four patients with pre-syncope guided patient management.

These data indicate that ILR monitoring facilitates the identification of mechanisms responsible for recurrences and therapeutic management in subjects with syncope or pre-syncope and negative traditional neurological and cardiovascular work-up.