Early syncope prediction by a new neuronal approach
Résumé
The goal of this study is to present a method that predicts unexplained syncope or presyncope occurrences induced by a head-upright tilt-test (HUTT). The HUTT is based on the reproduction of symptoms in combination with hypotension and bradycardia induced by a tilt at 70 during 45 minutes. The main drawback is the duration of this test because, by adding the supine position of 10 minutes, the test could reach 55 minutes. Therefore, we propose a new predicting tool, based on a new neuronal approach (Generalised Mapping Regressor), that establishes a diagnosis by using only the supine position of the HUTT. In the experiments, 86 patients (mean age: 43+/- 15 years, range 18-73 years, 44 males and 42 females) with history of unexplained recurrent upright syncope or presyncope were included. During the supine position of the HUTT, 16 variables were determined: cardiovascular variables (heart rate, systolic and diastolic blood pressure, pulsed pressure, contractility index, maximum value and two time intervals based on the left ventricular ejection time), body composition variables (age, sex, body surface area, total body water, plasma volume, hematocrit, hemoglobin, ratio fat-free mass on fat mass). Those variables allowed to reach a prediction quality comparable with studies using the tilt position (85% of specificity and 80% of sensitivity were reached in a group test). We conclude that patients with a positive HUTT outcome are in an abnormal state that can be detected even before the head-up position. Cardiovascular variables are an important contributor to this abnormal state.