Abstract Body (Do not enter title and authors here): Background:
The diagnosis of VVS largely relies on clinical history and simple diagnostic tools (e.g., electrocardiogram) to rule out dangerous differential diagnoses. However, using the head-up tilt test (HUTT) has become controversial among clinicians. This retrospective study aims to evaluate whether the prodromal symptoms experienced during HUTT are consistent with those experienced during spontaneous syncope.

Methods:
This study utilized data from the HUTT registry at the Syncope Unit of the tertiary Heart Center, focusing on adults aged 18 and older diagnosed with VVS. Diagnoses were based on clinical histories, physical examinations, and the latest syncope guidelines. Out of 1914 patients with HUTT results, 764 patients with positive tests were analyzed for mutual prodromal symptoms during HUTT and spontaneous syncope.

Results:
The McNemar test revealed significant differences for several symptoms, including palpitation (X2 = 30.59, P < 0.001), nausea (X2 = 16.13, P < 0.001), chest pain (X2 = 24.32, P < 0.001), abdominal discomfort (X2 = 22.33, P < 0.001), flushing (X2 = 10.87, P < 0.001), and aura (X2 = 19.86, P < 0.001), indicating discrepancies in the occurrence of these symptoms. Cohen's Kappa values ranged from 0.06 to 0.32, signifying slight to fair agreement. Specifically, diaphoresis (k = 0.32), palpitation (k = 0.27), and vertigo (k = 0.25) demonstrated fair agreement, whereas nausea, aura, chest pain, abdominal discomfort, and flushing exhibited slight agreement. Among the 640 patients who experienced prodrome during spontaneous syncope, 110 (17.19%) had no symptoms. Conversely, among the 123 patients who did not experience prodrome, 96 (78.05%) experienced at least one symptom during the tilt test (Figure).

Conclusion:
The assessment of prodromal symptoms during HUTT compared to spontaneous syncope showed significant differences for several symptoms and overall low levels of agreement. Also, tilt cannot differentiate patients with or without prodrome during their spontaneous spells.