Midodrine in neurally mediated syncope: a double-blind, randomized, crossover study.
Neurally mediated syncope is the most frequent cause of syncope in patients without structural heart disease. Its most common trigger is a reduction in venous return to the heart due to excessive venous pooling in the legs. We conducted a double-blind, randomized, crossover trial to investigate the efficacy of midodrine, a selective alpha-1 adrenergic agonist that decreases venous capacitance, in preventing neurally mediated syncope triggered by passive head-up tilt. Twelve patients with history of recurrent neurally mediated syncope, which was reproduced during head-up tilt, were randomized to receive a nonpressor dose of midodrine (5mg) or placebo on day 1 and the opposite on day 3. One hour after drug or placebo administration, patients underwent 60-degree head-up tilt lasting 40 minutes (unless hypotension or bradycardia developed first). In the supine position, midodrine produced no significant change in blood pressure or heart rate. The responses to head-up tilt were significantly different on the midodrine and the placebo day: on the placebo day, 67% (8/12) of the subjects suffered neurally mediated syncope, whereas only 17% (2/12) of the subjects developed neurally mediated syncope on the midodrine day (p < 0.02). These results indicate that midodrine significantly improves orthostatic tolerance during head-up tilt in patients with recurrent neurally mediated syncope.
Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, USA. horacio.kaufmann@mssm.edu
Horacio
H
Kaufmann
Daniela
D
Saadia
Andrei
A
Voustianiouk
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007024:Hypotension, Orthostatic / Q000188:drug therapy / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D008879:Midodrine / Q000627:therapeutic use*; D019462:Syncope, Vasovagal / Q000188:drug therapy* / Q000517:prevention & control; D018667:Tilt-Table Test; D014662:Vasoconstrictor Agents / Q000627:therapeutic use*
D014662:Vasoconstrictor Agents; D008879:Midodrine