Cardiovascular variables do not predict head-up tilt test outcome better than body composition

Area of Science:

• Cardiology
• Physiology
• Biomedical Engineering

Background:

• Reflex syncope pathophysiology is not fully understood.
• Patients with syncope may exhibit pre-existing abnormalities.
• Head-up tilt testing (HUTT) is a diagnostic tool for syncope.

Purpose of the Study:

• To investigate if patients with a history of syncope and positive HUTT outcomes are in an abnormal state before the head-up position.
• To identify variables that can predict HUTT outcomes.
• To explore the role of cardiovascular and body composition variables in predicting syncope events.

Main Methods:

• A 45-minute HUTT was performed on 86 patients with a history of syncope.
• 19 variables (9 cardiovascular, 8 body composition, age, sex) were assessed during the supine period.
• Neural networks were employed to predict HUTT outcomes using the assessed variables.

Main Results:

• Individual variable analysis did not differentiate between positive and negative HUTT outcomes.
• Neural network analysis achieved 76% sensitivity, 81% specificity, 78% PPV, and 80% NPV for HUTT outcome prediction.
• Body composition variables alone provided prediction accuracy comparable to cardiovascular variables.

Conclusions:

• Patients with a positive HUTT outcome exhibit detectable abnormalities even before assuming the head-up position.
• Body composition is a significant factor contributing to the abnormal state observed in these patients.
• These findings suggest novel avenues for predicting and understanding reflex syncope.