VALUE AND LIMITATIONS OF THE TILT TEST IN THE DIAGNOSIS OF UNEXPLAINED SYNCOPE

This study was undertaken to assess the usefulness of the head-up tilt test in the diagnosis of vasovagal syncope and to evaluate the indica tions of this investigation. The test consists in a 30 minute period i n the horizontal decubitus position followed by a 60-degrees head-up t ilt position for 30 minutes. In the 26 subjects in whom the diagnosis of repeated vasovagal syncope had been made on the basis of typical pr odromic symptoms after exclusion of all other causes, the test induced a vasodepressive or vagal reaction in 10 cases (38 %) 20 +/- 4 minute s after tilting. In 8 patients in whom the test was performed within 4 8 hours of their syncopal episode, a similar malaise was induced in 7 cases. Twenty patients with repeated malaise without loss of conscious ness had no symptoms during the test which was also negative in 10 nor mal control subjects. In a group of 27 subjects with unexplained synco pe after clinical and paraclinical investigations, the test was accomp anied by a malaise on five occasions (19 %). Using this protocol, the tilt test had good specificity but moderate sensitivity in the diagnos is of vasovagal syncope. Its sensitivity increased when performed with in 48 hours of syncope. It is of no value in the diagnosis of recurren t malaise without loss of consciousness.