Sleep syncope: a prospective cohort study

Sleep syncope is defined as a form of vasovagal syncope which interrupts sleep. Long term follow-up has not been reported.

Between 1999 and 2013 we diagnosed vasovagal syncope in 1105 patients of whom 69 also had sleep syncope. We compared these 69 patients in the sleep syncope group to 118 patients with classical vasovagal syncope consecutively investigated between 1999 and 2003. We compared baseline demography, syncope history, tilt test results and follow-up findings.

At baseline, age and gender distribution (mean ± standard deviation) of the classical VVS and sleep synocope groups were similar: 46 ± 21 vs. 47 ± 15 years (p  = 0.53), and 55% versus 66% female (p  = 0.28), respectively. Abdominal discomfort and vagotonia were more frequent in sleep syncope patients: 80% versus 8% and 33% versus 2% (p  < 0.001). Childhood syncope and blood-needle phobia were also more frequent in sleep syncope patients: 58% versus 15% and 69% versus 19% (p  < 0.001). Positive tilt test results were similar for the two groups (93% [classical VVS] vs. 91%; p  = 0.56). Blood pressure, heart rate and stroke volume changed in a similar manner from baseline to syncope (p  = 0.32, 0.34 and 0.18, respectively). Mean duration of follow-up for the classical VVS and sleep syncope groups, as recorded in the electronic records, were 17 (3-21) and 15 (7-27) years, respectively. Rates of mortality and of permanent pacemaker insertion were similar in the two groups: 16.2% (classical VVS) versus 7.6% (p  = 0.09) and 3% (classical VVS) versus 3% (p  = 0.9). Incidence of sleep episodes decreased from 1.9 ± 3 to 0.1 ± 0.3 episodes per year (p  < 0.001).

Sleep syncope is a subtype of vasovagal syncope with characteristic symptoms. Despite the severity of the sleep episodes, the prognosis is very good. Very few patients require permanent pacing, and nearly all respond to education and reassurance.