Michele Brignole, Richard Sutton, Carlo Menozzi, Antonio Raviele, Paolo Alboni, Paolo Giani, Angel Moya on behalf of the Vasovagal Syncope International Study (VASIS) Investigators*.
Departments of Cardiology oc:\www Ospedali Riuniti, Lavagna, Italy, Royal Brompton Hospital, London, UK, Ospedale S. Maria Nuova, Reggio Emilia, Ospedale Umberto I, Mestre, Ospedale Civile, Cento, Ospedale Bolognini, Seriate, Italy, Hospital Vall d’Hebron, Barcelona, Spain. *A complete list of Investigators appears in Appendix
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The pacemaker protocol of the Vasovagal Syncope
International Study (VASIS) was designed to investigate whether dual-chamber pacing is able
to prevent syncopal recurrences in patients with severe cardioinhibitory tilt positive responses.
Study protocol
The study was prospective, controlled, multicentre with central randomization: therapy versus
no therapy. The study tested the hypothesis that a decision to implant a DDI pacemaker with
rate hysteresis would reduce the risk of recurrence of syncope compared to not implanting a
pacemaker. Main aim of the study was to evaluate the ability of the active therapy to reduce
the interval to first recurrence of syncope. Secondary aims were: to investigate whether
pacing is able to reduce the total burden of syncopal recurrences; to evaluate the natural
history of tilt-induced cardioinhibitory neurally-mediated syncope; to evaluate the acute
effect of pacemaker therapy during tilt testing; to test the utility of the VASIS classification of
tilt-induced syncope to identify patients who may benefit from pacing therapy.
Patients eligibility
To be included in the study, the patients affected by neurally-mediated syncope had to fulfill all
the following 3 conditions: at least 3 syncopal episodes in the last 2 years with the last
episode occurring within 6 months of enrolment and with an interval between the first and the
last episode >6 months; positive VASIS 2A or 2B cardioinhibitory response to head-up tilt
testing; and age more than 40 years or, if less than 40 years, proven refractoriness to
conventional drug therapy.
Findings
Before enrolment, the patients had had a median of 6 syncopal episodes. A severe
cardioinhibitory response to tilt testing causing a prolonged asystolic pause >3 s was present
in 36 of 42 patients (86%) with a mean ventricular pause 13.9±10.2 s (median 11.5 s, range
3-34 s).
In the intention-to-treat analysis, syncope recurred in 1 patient (5%) in the pacemaker arm
after 15 months and in 14 patients (61%) in the no-pacemaker arm after a median of 5 months
(interquartile range 2-20). The results of the secondary end-point are listed in the table I. The
difference was highly significant, (p=0.0006). In no case did syncopal relapse cause injury.
TABLE I – Primary and secondary outcome events by groups
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