Prevalence, timing, and haemodynamic correlates of prodromes in patients with vasovagal syncope induced by head-up tilt test.

Aims: To evaluate the prevalence, timing, and haemodynamic characteristics of prodromal symptoms in patients experiencing vasovagal syncope (VVS) during a head-up tilt test (HUT) potentiated with nitroglycerin, and their relationships with those reported before spontaneous episodes.
Methods and Results: Symptoms preceding HUT-induced syncope were recorded, together with heart rate (HR) and arterial blood pressure (BP) values, in 149 otherwise healthy and drug-free subjects with recurrent unexplained syncope. Head-up tilt test significantly increase the number of patients capable of recognizing the premonitory symptoms of VVS than before spontaneous episodes (96 vs. 79%; P<0.001). The nine most frequent symptoms were stratified into three groups on the basis of their characteristics: headache, hot flashes, and palpitations occurred more than 3 min before syncope, with a very slight reduction in BP; nausea, asthenia, diaphoresis, vertigo, and epigastric discomfort preceded syncope by 1-3 min and were associated with a slight reduction in BP; and blurred vision appeared the last minute before syncope and was characterized by the lowest BP and HR values.
Conclusion: In comparison with spontaneous syncopal episodes, HUT allows the more frequent recognition of prodromes also providing useful information in terms of timing and haemodynamic characteristics of symptoms that may allow more tailored patient counselling.