Recurrent syncope in patients with carotid sinus hypersensitivity.

Syncope recurrence in pacemaker-implanted subjects for the cardio-inhibitory response to sinus carotid massage (SCM) was investigated. The study-hypothesis was that recurrences had significant vasodepressor responses that could justify the loss of consciousness. Forty-six patients were enrolled (16 patients and 30 controls), followed and revaluated after 5-7 years. At the end of follow-up, significant differences were found between patients and controls in mean SCM SAP (87 versus 106 mmHg) and reduction in mean SCM SAP (59 versus 38 mmHg); in the number of symptomatic subjects soon after SCM (5 versus 1); and in the number of subjects suffering from orthostatic hypotension. A subgroup of 13 patients showed significantly different hypotensive responses to SCM compared with the values observed at study recruitment. The data showed that some subjects with a defined hemodynamic pattern in response to SCM may change their characteristics and have spontaneous and/or provocative symptoms. These data explain the syncopal relapses, and suggest the presence of autonomic dysregulation in individuals with carotid sinus hypersensitivity.