Copeptin in vasovagal syncope

Purpose: The arginine-vasopressin (AVP) system is one of the main blood pressure regulating systems. Copeptin is a stable and sensitive surrogate marker for AVP release. Vasovagal syncope (VVS) is the most common type of syncope. The purpose of this study was to assess copeptin, as a marker of AVP system responsiveness, in patients (pts) with VVS during a diagnostic head-up tilt test (HUT). Methods: We studied 26 pts with typical history of recurrent VVS (at least 2 episodes during the preceding 6 months), without underlying cardiovascular disease or renal dysfunction, mean aged 52±6 years, 12 males/14 females, who underwent a diagnostic, positive HUT. Fourteen similar pts without history of syncope and a subsequently negative HUT served as controls. We assessed copeptin plasma levels by the CRYPTOR Copeptin Assay (BRAHMS) prior to and 10 min following HUT positivity or HUT termination (controls). A p value <0.05 was considered statistically significant. Data are presented as mean ± SD. Results: Baseline copeptin values were similar in the 2 groups (9.3±5.6 pmol/l in pts vs 7.9±3.6 pmol/l in controls, p: NS). A significant difference was observed in copeptin values between the 2 groups following HUT termination (80.2±75 vs 13.6±9.4 respectively, p<0.05). Copeptin levels increased with HUT in VVS pts (from 9.3±5.6 to 80.2±75, p<0.05), exceeding the upper limit of normality (14 pmol/l) in 17/26 (65%) pts, but in only 3/13 (23%) controls (p<0.05). Conclusions: In pts with VVS and a positive HUT, copeptin values are greatly increased. This may be of pathophysiologic significance for VVS and warrants further investigation. Since copeptin values have been proposed as diagnostic and prognostic markers in other cardiovascular conditions, such as acute ischemia and shock, the findings of the present study should be taken into consideration.