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

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 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.