Pacing for neurally-mediated syncope: How to decide?

Neurally-mediated syncope has a broad clinical spectrum which ranges from typical vasovagal syncope on one hand, to those situations in which reflex syncope occurs with uncertain, or even apparently absent, triggers or prodromes, on the other hand. Overlap of clinical features is frequent in clinical practice and makes any classification difficult to apply when selecting patients for cardiac pacing. Typically, the reflex is both hypotensive and cardio-inhibitory. The rationale for efficacy of cardiac pacing is that the cardio-inhibitory reflex is dominant, since there is no role for pacing in preventing vasodilatation and hypotension. Establishing a relationship between symptoms and cardio-inhibitory reflex should be the goal of the clinical evaluation before embarking on permanent pacing. Similar efficacy has been observed in patients affected by dominant cardio-inhibitory reflex irrespective of the clinical form. In general, cardiac pacing should be considered last choice applied only in highly selected patients, i.e. those ≥ 40 years of age, affected by severe forms of reflex syncope with recurrences associated with frequent injury, often due to the lack of prodromes. Recurrence of syncope may still occur despite cardiac pacing in a minority of patients.