Finally, a Drug Proves to Be Effective Against Vasovagal Syncope!: But Not in All Patients.

SEE PAGE 1 M any drugs have been tested for the treatment of vasovagal syncope; for the most part, the results have been disappointing. The list includes beta-blockers, disopyramide, scopolamine, theophylline, ephedrine, etilefrine, midodrine, clonidine, and serotonin reuptake inhibitors. Although results have been satisfactory in uncontrolled trials or short-term controlled trials, the few long-term placebo-controlled prospective trials conducted have been unable to show a benefit of the active drug over placebo. For example, because failure to achieve proper vasoconstriction of the peripheral vessels commonly occurs in reflex syncope, alpha-agonist vasoconstrictors (etilefrine and midodrine) have been used. Etilefrine has been studied in a large randomized, placebo-controlled, double-blind clinical trial (1). During follow-up, patients treated twice daily with etilefrine 25 mg or placebo showed no difference in the frequency of syncope or the time to recurrence. Midodrine has proved effective in 4 small studies (2), but none of these satisfied the criteria of a pivotal clinical trial. Beta-blockers have been advocated in vasovagal syncope on the presumption that they lessen ventricular mechanoreceptor activation owing to their antisympathetic and negative inotropic effect in reflex syncope. However, beta-blockers failed to be effective in 2 randomized double-blind controlled trials (3,4), and the underlying rationale has been questioned.