The nitroglycerin (NTG) potentiated head-up tilt test (HUTT) positivity rate was about 1.5 times higher in patients with classical vasovagal (VVS) compared to those with non-classical VVS. The higher HUTT positivity rate observed in patients with classical VVS syncope was mainly due to the higher rate of mixed responses. The relative prevalence of cardioinhibitory forms was higher in patients with non-classical VVS. Among this subgroup, Traumatic syncope, use of diuretics and male sex were independent predictors of HUTT positivity.
