Low Adrenomedullin and Endothelin-1 Predict Cardioinhibitory Response During Vasovagal Reflex in Adults Over 40 Years of Age
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Vasovagal reflex syncope (VVS) is a common cause of syncope that may be identified by tilt testing.1 Dual-chamber pacing has been found to reduce syncope recurrence in patients ≥40 years with cardioinhibitory type of VVS with asystole.2,3 In the SUP-2 (Syncope Unit Project 2), a selection algorithm, based on asystole during carotid sinus massage, tilt testing, or implantable loop recording, effectively selected patients that benefitted from pacing.3
We hypothesized that differences in neuroendocrine profile exist between patients ≥40 years with cardioinhibitory and noncardioinhibitory syncope and, if found, would play a part in identifying patients who may benefit from pacing. We, thus, aimed to relate patient characteristics and resting plasma levels of 4 neuroendocrine biomarkers to different forms of VVS.
We included consecutive patients ≥40 years with unexplained syncope referred for head-up tilt testing (HUT). Patients with carotid sinus syndrome, orthostatic hypotension, or postural tachycardia syndrome were excluded. In total, 159 patients, 40 to 89 years, were included and provided supine blood samples followed by tilt according to the Italian protocol.4 Patients were classified as negative HUT, noncardioinhibitory, nonasystolic cardioinhibitory, and asystolic VVS according to the …