Clinical Question

Can midodrine decrease recurrent episodes of vasovagal syncope?

Bottom Line

Midodrine is a vasoconstrictor used to prevent orthostatic hypotension and may reduce the likelihood of recurrence of vasovagal syncope in patients with frequent episodes. It seems to work completely or not at all; during this study, the patients who had at least one episode of syncope had several episodes over the course of the year regardless of whether they received midodrine or placebo. (Level of Evidence = 1b−)

Synopsis

The investigators enrolled 133 adults without orthostatic hypotension who had fainted at least twice (median = six times) in the past year and who did not have other known causes of syncope. Patients were randomized, concealed allocation unknown, to receive placebo or midodrine for one year. Treatment was started at 5 mg three times daily, during daylight hours, with the dosage increased up to 10 mg three times daily, if tolerated. Over one year, 58% of patients in the midodrine group were syncope-free compared with 39% in the placebo group (number needed to treat = 5). Midodrine was associated with a longer time to first recurrence of syncope (P = .035). In the subset of participants who had at least one syncope episode during the study, the rates were similar between treatments (i.e., 3.6 to 3.8 episodes per year).

Study design: Randomized controlled trial (double-blinded)

Funding source: Industry and government

Allocation: Uncertain

Setting: Outpatient (specialty)

Reference: Sheldon R, Faris P, Tang A, et al. POST 4 investigatorsMidodrine for the prevention of vasovagal syncope: a randomized clinical trial. Ann Intern Med. 2021;174(10):1349–1356.

Editor’s Note: Dr. Shaughnessy is an assistant medical editor for AFP.