Level 1: Likely reliable evidence
Beta blockers appear to be no more effective than placebo for the treatment of vasovagal syncope. In a randomized trial, 30 patients with recurrent vasovagal syncope and positive tilt test were randomized to propranolol (Inderal, Inderal-LA) 20-40 mg three times daily vs. nadolol (Corgard) 40-80 mg once daily vs. placebo once daily for three months each in crossover fashion (J Am Coll Cardiol. 2002;40:499-504). All three treatments (including placebo) were associated with reduced spontaneous syncopal and presyncopal recurrence rates with no differences between treatments.
A more recent study evaluated the effect of another beta blocker, metoprolol (Lopressor, Toprol XL), in 208 patients with vasovagal syncope similarly defined as recurrent syncope and positive tilt test (Circulation. 2006;113:1164-1170).
Patients were randomized to metoprolol (50 mg twice daily, increased to 100 mg twice daily if tolerated) or placebo for one year. In an intent-to-treat analysis, there were no significant differences between metoprolol vs. placebo: 36.1% vs. 36% had syncope and 22.2% vs. 22% withdrew from the study.