LIMITATIONS OF HEAD-UP TILT TEST FOR EVALUATING THE EFFICACY OF THERAPEUTIC INTERVENTIONS IN PATIENTS WITH VASOVAGAL SYNCOPE - RESULTS OF ACONTROLLED-STUDY OF ETILEFRINE VERSUS PLACEBO

Objectives. 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 etilefr ine can be effective either in preventing a positive response to head- up tilt testing or in reducing syncopal recurrences in patients with v asovagal syncope. Up to now most studies assessing drug therapy in the se patients have been uncontrolled. Methods. This was a randomized dou ble-blind crossover study of etilefrine versus placebo in 30 consecuti ve patients with syncope and a baseline positive head-up tilt test. Af ter the first test, patients had no treatment for 3 days and were rand omized to receive etilefrine or placebo for 4 additional days. They un derwent 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 rat e of positive responses decreased with repeated testing irrespective o f the assigned treatment: A positive response was obtained during the second head-up tilt test in 20 patients (10 with placebo, 10 with etil efrine) but in only 12 during the third (7 with etilefrine, 5 with pla cebo) (p < 0.05). Conclusions. Oral etilefrine (10 mg three times a da y) was not superior to placebo in preventing a positive response to he ad-up tilt testing, Despite a low statistical power, the high rate of negative response with placebo (50%) suggests that controlled trials a re needed to assess the real efficacy of any treatment in patients wit h vasovagal syncope.