Fast Tilt Test: a New Paradigm in the Management of Reflex Syncope

pp. 42-49

Abstract

Introduction
Between 20% and 30% of persons present syncope throughout their lives and reflex syncope represents the most common cause. The differential diagnosis of syncope is based on the characteristics of the episode and on the reproducibility of symptoms with the head-up tilt test. Yet, as tilt test has important limitations, we began exploring a new parameter in successive stages of investigation, which we called “delay of the carotid pulse wave”.

Objectives
To present the results of the investigation about the discovery, development and clinical applicability of the parameter: “delay of the carotid pulse wave”, capable of identifying patients with reflex syncope.

Methods
The development of the idea and the results of the analysis of the correlation between the parameter and the tilt test evaluated in a pilot study of 43 patients with syncope are described. The correlation is confirmed in 100 patients with syncope and in controls; the pathophysiological mechanism of the parameter is evaluated; the design of an automated device is described and its validation is confirmed in a multicenter study of 100 patients with history of syncope using drug-stimulated head-up tilt test. The search of a new gold standard for reflex syncope is described.

Results
The statistical analysis performing univariate and multivariate models and the construction of ROC curves on 243 patients undergoing head-up tilt test showed that, despite the different ages or methods used, the parameter classified in a correct fashion more than 80% of patients with history of syncope and positive head-up tilt test and 100% of volunteers without history of syncope who presented positive head-up tilt test. The measurement of the parameter without using a tilt table identified 100% of volunteers with history of syncope (7/30).

Conclusions
We developed a simple and non-invasive measurement parameter, capable of predicting a positive head-up tilt test within 5 minutes in patients with syncope and of identifying people with history of syncope without using the tilt table. The parameter could help to  make rapid diagnostic decisions in patients with syncope, to understand the pathophysiological aspects and to evaluate the therapeutic interventions.