Aims: To assess the relation between the timing of syncopal attacks and tilt test positivity.
Method and results: Prospective comparisons of distribution of syncopal attacks in 49 consecutive neurally mediated cardiac syncope (NMCS) patients (19 boys, 30 girls, mean age 13.7+/-0.68) were evaluated. Head-up tilt test (HUT) was positive in 28 patients and negative in 21. A questionnaire was given to every patient about the time and number of the syncopal attacks, presyncopal symptoms or signs before HUT. Although syncopal attacks were found to be concentrated in the morning especially between 10 AM and 12 noon in HUT positive patients (P < 0.001), there was a concentration in the late afternoon and evening period of the day especially between 2 PM and 6 PM in HUT negative patients (P < 0.001).
Conclusion: It was assumed that diurnal variation in autonomic function may be the factor in the timing of syncopal events during morning hours in the HUT positive NMCS children and adolescents.