733 Vasovagal syncope: prognostic factors for syncope recurrences

value from Mann-Whitney test. Standard deviation of the normal-to-normal beat interval averages calculated over 5 minutes (SDANN) and lowfrequency power (LF% n.u.) were significantly lower in ARVD patients than in healthy controls; there were no differences in measures of parasympathetic activity. There were no significant differences in QTc duration between groups. However, QT variability was increased and QT/RR slopes were steeper in ARVD patients than in controls. Conclusions: Young ARVD patients show decreased heart rate variability, increased QT variability, and signs of abnormal QT adaptation that might contribute to an increased risk of arrhythmic events.