Background and Objective: The tilt table test is a diagnostic modality used to evaluate patients presenting with altered levels of consciousness (ALOC) or orthostatic symptoms. The autonomic nervous system's response to postural changes induces alterations in sympathovagal tone, subsequently altering various electrocardiographic (ECG) parameters. The index of cardio-electrophysiological balance (iCEB) is calculated based on the ratio of the QT interval to the QRS duration, serving as a non-invasive measure of the cardiac impulse wavelength. The present study aimed to evaluate changes in the iCEB during the tilt table test in patients with ALOC.
Methods: This case-control study was conducted using a convenience sampling method on the medical records of 40 patients selected from among 390 patients with ALOC who visited the tilt table Laboratory at Ayatollah Taleghani Educational and Medical Center in Gorgan, Golestan Province, Iran. The participants were divided into two groups of 20 (10 males and 10 females per group). Based on medical records, 20 patients with a positive tilt table result were initially selected, followed by the random selection of 20 patients with a negative tilt table result, who were age- and sex-matched with the first group. The data related to patients’ ECG, blood pressure, and pulse rate were recorded and compared prior to the test (baseline conditions), during tilt, and during recovery.
Results: The mean and standard deviation of iCEB in the positive tilt table group at baseline, tilt, and recovery phases were determined to be 6.04±1.48, 6.18±1.85, and 6.81±1.72, respectively. In the negative tilt table group, these values were 4.67±2.01, 4.46±2.07, and 4.48±2.19, respectively. Between-group comparisons revealed a statistically significant increase in the iCEB among patients with positive tilt table results compared to those with negative tilt table results during the baseline, tilt, and recovery phases (P<0.05). However, the values were not statistically significant for the corrected iCEBc.
Conclusion: Baseline values of the iCEB may serve as useful predictors for tilt table test results in patients presenting with ALOC.