Prevention of Syncope Trial (POST): a randomized clinical trial of beta blockers in the prevention of vasovagal syncope; rationale and study design.
BACKGROUND
Few therapies for vasovagal syncope have been proven effective. A large, placebo-controlled clinical trial of beta-blockers is needed.


METHODS
The Prevention of Syncope Trial (POST) is a multicentre, randomized, placebo-controlled, study of metoprolol in the prevention of vasovagal syncope. The primary hypothesis is that beta-blockers will increase the time to the first recurrence of syncope when compared with placebo. Patients will be randomized 1:1 to receive metoprolol or placebo, and followed for 1 year. The primary endpoint is the time to first syncope recurrence, and secondary endpoints include syncope frequency, presyncope, and quality of life.


METHODS
Patients are eligible if they have a positive tilt test and 3 syncopal spells preceding the tilt test. They are excluded if they have seizures or other causes of syncope; important heart disease; a contraindication to or need for beta blockers; a permanent pacemaker; a major noncardiovascular disease; or previous use of beta blockers at a dose greater than the equivalent of metoprolol 25mg twice daily for the purpose of suppressing vasovagal syncope.
We assume a 40% risk of syncope in the control arm, an absolute reduction of 20% by metoprolol, and a dropout of 20%. Entry of 220 patients will result in an 80% chance of reaching a positive conclusion about beta-blocker therapy with 2p=0.05.
Sheldon
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Cardiovascular Research Group, University of Calgary, Calgary, Alberta, Canada. sheldon@ucalgary.ca
Rose
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Connolly
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D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D006801:Humans; D008790:Metoprolol / Q000627:therapeutic use*; D008875:Middle Aged; D011446:Prospective Studies; D011788:Quality of Life; D012008:Recurrence; D012107:Research Design; D019462:Syncope, Vasovagal / Q000503:physiopathology / Q000517:prevention & control*; D018667:Tilt-Table Test
D000319:Adrenergic beta-Antagonists; D008790:Metoprolol