Efficacy Of Intravenous Atenolol For Prevention Of Neurally Mediated Syncope Induced By Head-Up Tilt Testing

The treatment of neurocardiogenic syncope is still a clinical problem. The beta-blockers have been widely used for this purpose as st first line drug. In spite of that, there are not many studies that establish the real efficacy of those drugs in patients with recurrent episodes of this kind of syncope. We are performing in our hospital a prospective, randomized, double blind and controlled study on the efficacy of intravenous and oral atenolol in patients with neurocardiogenic syncope. 50 patients with clinically diagnosed vasovagal syncope were included. A complete study to discard other possible causes of syncope was performed in all patients. After a baseline tilt test with a protocol of 80 degrees during 45 minutes, all the patients (18) with a positive response underwent an infusion of intravenous atenolol. 4 patients with a positive baseline test did not accept the infusion of that drug and, therefore, they were not included in this protocol. Atenolol prevented a second positive tilt in 5 of 18 patients (27,8%). There were no significant differences between both groups with respect to age, gender, blood pressure, heart rate and number of syncopes. 13 patients had a recurrent positive response in spite of atenolol. II of these subjects had a syncope during the first tilt test. In 7 of them (63.6%) atenolol prevented severe symptoms (syncope) in the second test. In patients with a significant cardioinhibitory response in the first test, atenolol did not prevent a second positive response in anyone.