What can I do when first-line measures are not enough for vasovagal syncope?

MEDICAL THERAPY

In patients who continue to have syncopal episodes despite adequate use of first-line measures, medical therapy can be considered. Unfortunately, evidence supporting drug therapy for recurrent syncope is limited.³ Options include midodrine (class IIa), fludrocortisone (class IIb), beta-blockers (class IIb), and selective serotonin reuptake inhibitors (class IIb).¹

Midodrine has the strongest recommendation and is a reasonable option if there is no history of hypertension, heart failure, or urinary retention. It is a peripheral alpha-agonist that ameliorates the reduction in peripheral sympathetic neural outflow responsible for venous pooling and vasodepression in vasovagal syncope.^4–6

Fludrocortisone results in increased blood volume due to mineralocorticoid activity. In the Prevention of Syncope Trial 2 of fludrocortisone vs placebo, patients on fludrocortisone had a “marginally nonsignificant” reduction in recurrence of syncope over 1 year (hazard ratio 0.69, P = .069).⁷

Overall, beta-blockers have failed to prevent syncope in randomized controlled trials. But in a meta-analysis that included patients from the Prevention of Syncope Trial,⁸ an age-dependent benefit of beta-blockers was noted in patients age 42 and older.⁹ Therefore, a beta-blocker may be a reasonable option in patients in this age group with recurrent vasovagal syncope.¹

Serotonin has central effects on blood pressure and heart rate that can induce syncope. However, evidence for the effectiveness of selective serotonin reuptake inhibitors in the prevention of recurrent vasovagal syncope has been contradictory in small trials.^10,11

When choosing a drug, contraindications should be considered, including possible effects during pregnancy in women of childbearing age.

OTHER MEASURES

Orthostatic training, with repetitive tilt-table testing until a test is negative, or with daily standing quietly against a wall for prolonged periods of time, has not been shown to have sustained benefit in reducing the recurrence of syncopal episodes (class IIb recommendation).¹

Dual-chamber pacing can be considered in carefully selected patients age 40 or older with syncope and documented asystole of at least 3 seconds or spontaneous pauses of at least 6 seconds without syncope on implantable loop recorder monitoring (class IIb recommendation).^1,12,13 Strict patient selection increases the likelihood that pacing will be effective.¹ For example, patients with documented asystole during syncope and a tilt-table test that induces minimal or no vasodepressor response are more likely to respond than patients with a positive tilt-table test with a vasodepressor (hypotensive) response.¹³

Tilt-table testing may also be considered to identify patients with a hypotensive response who would be less likely to respond to permanent cardiac pacing.¹⁴ 


Compression garments carry a class IIa recommendation for orthostatic hypotension,1 but they have not been adequately studied in vasovagal syncope.