Limitations of head-up tilt test for evaluating the efficacy of therapeutic interventions in patients with vasovagal syncope: results of a controlled study of etilefrine versus placebo.
OBJECTIVE
This study assessed the efficacy of oral etilefrine (10 mg three times a day) in preventing a positive response to head-up tilt testing.


BACKGROUND
Previous reports have suggested that oral etilefrine can be effective either in preventing a positive response to head-up tilt testing or in reducing syncopal recurrences in patients with vasovagal syncope. Up to now most studies assessing drug therapy in these patients have been uncontrolled.


METHODS
This was a randomized double-blind crossover study of etilefrine versus placebo in 30 consecutive patients with syncope and a baseline positive head-up tilt test. After the first test, patients had no treatment for 3 days and were randomized to receive etilefrine or placebo for 4 additional days. They underwent tilt testing under treatment and again after 3 days of washout; they then received the alternative treatment for 4 days, and a third test was performed.


RESULTS
Head-up tilt test results were negative in 13 (43%) patients with etilefrine and 15 (50%) with placebo (p = NS). Therefore, the statistical power of the study was only 10%. The rate of positive responses decreased with repeated testing irrespective of the assigned treatment: A positive response was obtained during the second head-up tilt test in 20 patients (10 with placebo, 10 with etilefrine) but in only 12 during the third (7 with etilefrine, 5 with placebo) (p < 0.05).


CONCLUSIONS
Oral etilefrine (10 mg three times a day) was not superior to placebo in preventing a positive response to head-up tilt testing. Despite a low statistical power, the high rate of negative response with placebo (50%) suggests that controlled trials are needed to assess the real efficacy of any treatment in patients with vasovagal syncope.
Moya
A
A
Servei de Cardiologia, Hospital General Universitari Vall d'Hebron, Barcelona, Spain.
Permanyer-Miralda
G
G
Sagrista-Sauleda
J
J
Carne
X
X
Rius
T
T
Mont
L
L
Soler-Soler
J
J
D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005039:Etilefrine / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010919:Placebos; D013575:Syncope / Q000175:diagnosis* / Q000188:drug therapy*; D018667:Tilt-Table Test / Q000706:statistics & numerical data
D010919:Placebos; D005039:Etilefrine