Clinical Factors Affecting a Response of Head-Up Tilt Test in Suspected Neurally Mediated Syncope

The purpose of this study was to assess the clinical factors affecting the results of the HUT in suspected neurally mediated syncope. From Oct. 1994 to Sep. 2009, HUT was consecutively performed to 3,740 patients with suspected neurally mediated syncope. We compared clinical factors of a positive response group (2,260 patients) with those of a negative response group(1,480 patients).The most common type of a positive response of HUT was a vasodepressive type (74.6%), followed by a mixed type (19.7%) and a cardio-inhibitory type (5.7%). By multivariable analysis, a blurred vision (p=0.049), pallor (p=0.010), and sweating (p=0.013) were found to be associated with a positive response of HUT. However, old age (p>0.0001), male gender (p=0.004), sitting situation (p=0.004), diabetes (p=0.007), and hypertension (p>0.001) were found to be associated with a negative response of HUT.In contrast to previous studies, the time interval between the last episode before HUT and HUT (p=0.48) and frequency of syncope (p=0.35) were not a predictor of a positive response of HUT. Clinical factors seem to be a useful for predicting a response of HUT in patients with suspected neurally mediated syncope.