Update on the Role of Pacemaker Therapy in Vasovagal Syncope and Carotid Sinus Syndrome

Vasovagal syncope (VVS) and carotid sinus syndrome (CSS) are related, neurally mediated disorders with different clinical features and treatment implications. Pacemaker intervention studies in both syndromes are hampered by a dearth of randomized, controlled (particularly with placebo) studies, unfortunate premature termination of studies, and variation in both the clinical presentation and cardiovascular profile of patients enrolled. Given this relatively limited evidence base, pacing therapy in VVS should be reserved for older sufferers with relatively frequent symptoms and spontaneous asystole documented during real-life monitoring. The long term course of patients paced for vasovagal syncope needs clarification, both in terms of symptom and device-related burden, while a comprehensive health economic evaluation of the costs and benefits of such an invasive approach for this usually benign condition is essential. It will also be important to determine the efficacy of closed loop stimulation pacing in an adequately powered study, including a comparison with standard pacing.Pacing should be considered in those with unexplained syncope with reproduction of symptoms during a cardio-inhibitory or mixed response to carotid sinus massage (asystole > 3 s), though the evidence base for this recommendation is firmly in the consensus rather than pragmatic randomized controlled trial camp. Patients presenting with unexplained falls and drop attacks, particularly where injuries are prominent and where patients cannot give a clear account of their fall (“I just ended up on the floor, didn't slip or trip”), should also be considered for pacing. Pacing is not recommended for the vasodepressor sub-type of CSS.