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

Aims: 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.

Methods: 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.

Results: 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.

Conclusions: 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.