# Diagnostic Power of Head-Up Tilt Test Enhanced by Autonomic ECG Parameters and Beat-to-Beat Hemodynamic Monitoring

## TL;DR

This study shows that adding advanced ECG and blood pressure monitoring to a tilt test improves the ability to diagnose syncope.

## Contribution

The study introduces autonomic ECG parameters and continuous hemodynamic monitoring to enhance the diagnostic accuracy of the head-up tilt test.

## Key findings

- The extended protocol detects more pronounced hemodynamic fluctuations and enables real-time trend analysis.
- Patients with syncope showed significantly higher PRD values during the tilt phase (8.14 vs. 3.91 deg², p=0.043).
- Continuous monitoring allows earlier recognition of impending syncope and better identification of its cause.

## Abstract

Objectives: The head-up tilt test (HUTT) is a well-established diagnostic procedure used to differentiate between the types of syncope. Since its introduction in 1986, the protocol has undergone several refinements aimed at increasing diagnostic accuracy. Despite growing interest in advanced autonomic ECG parameters and beat-to-beat blood pressure monitoring, their integration into routine HUTT protocols remains limited.

Methods: In this study, we compared the conventional HUTT protocol using two-minute interval monitoring with an advanced protocol incorporating autonomic ECG parameters—periodic repolarization dynamics (PRD) and deceleration capacity (DC)—as well as continuous beat-to-beat hemodynamic monitoring.

Results: The extended protocol improves diagnostic resolution by detecting more pronounced hemodynamic fluctuations, enabling real-time trend analysis, and allowing earlier recognition of impending syncope. The tilt phase was characterized by a significant initial increase in PRD, and patients with syncope showed significantly higher PRD values during the tilt phase (8.14 vs. 3.91 deg2, p=0.043).

Conclusions: Continuous hemodynamic monitoring during HUTT improves the diagnostic quality by detecting changes at an early stage, thus allowing to anticipate syncope and to clearly identify its etiology. While beat-to-beat blood pressure monitoring is already recommended by current syncope guidelines, we propose the additional evaluation of autonomic ECG parameters as a valuable extension to standard protocols.