The clinical characteristics and response to head-up tilt test of patients with micturition syncope: single-center experience in China.

Objective: This study compared clinical characteristics and response to head-up tilt test (HUTT) between micturition syncope (MS) and typical vasovagal syncope (VVS).

Methods: Consecutive patients who underwent nitroglycerin-potentiated HUTT were retrospectively dichotomized into two groups: those with a history of MS and those with a history of VVS. The patients with MS were further subdivided into patients with MS alone and with MS and at least one episode of VVS.

Results: A total of 2637 patients were enrolled: 204 had MS (MS alone in 103 and MS+VVS in 101), and 216 had typical VVS. Patients with MS were older (38.6 ± 13.1 vs. 36.3 ± 18.5, p = 0003) and more likely to be male (66.2% vs. 48.1%, p < 0.001). Multivariable analysis revealed that smoking habit (odds ratio [OR] 2.16, p < 0.0001), history of traumatic syncope (OR 2.24, p = 0.0001), and drinking alcohol before syncope (OR 2.63, p < 0.0001) were independently associated with MS. HUTT was positive in 141 (69.1%) patients with MS and in 144 (66.7%) patients with VVS (p = 0.592). Patients with MS showed more mixed (46.1% vs. 28.2%, p < 0.001) and vasodepressor forms (15.2% vs. 7.9%, p = 0.013) and fewer cardioinhibitory responses than others (7.4% vs. 30.6%, p < 0.001).

Conclusions: Compared with VVS, patients with MS have different clinical characteristics, and drinking alcohol was an important precipitating factor for MS. The positivity rate of HUTT is high and similar to that of VVS, although patients with MS show a higher prevalence of hypotensive responses.