Is the Type of Cardiovascular Response During Tilt Table Testing Useful for the Choice of the Treatment? The New VASIS Classification

Abstract

Worldwide experience of more than 10 years of tilt testing has shown that, while it has dramatically reduced the number of patients whose syncope cannot be explained, the population of patients who show a positive response to the test is greatly heterogeneous, raising the possibility that different syndromes can be diagnosed by tilt testing. Many drugs as well as cardiac pacing have been proposed for patients with tilt-induced syncope; however, a consensus on management has not been achieved due to the unsatisfactory results of trials of therapy which have been undertaken. The classification of the Vasovagal Syncope International Study (VASIS) was developed in 1992 in order to facilitate the understanding of the different types of vasovagal reactions that were observed during tilt-induced syncope [1]. This has been recently extended to tilt testing with pharmacological challenge [2, 3]. Like the other current classifications of the positive responses to tilt testing, the VASIS classification is based on the different behaviour of the blood pressure and heart rate observed when the vasovagal reaction and symptoms occur. To date, the cardiovascular patterns preceding the development of the vasovagal reaction have received little study. We believe that the pattern of blood pressure response to tilt may provide more strict diagnostic information and that a more detailed although still arbitrary classification may form the basis of a number of future drug and pacemaker trials and may help us toward a better understanding of the different mechanisms of tilt-induced syncope. We, therefore, propose that the following classification should be used as a complementary classification in addition to the VASIS classification. Moreover, we have tried to correlate this classification with some simple clinical variables.