Decreased cerebral blood flow in a supine position in patients with a history of syncope and presyncope during the Tilt Table Test

Objective To analyze the hemodynamic response, cerebral blood flow, and the sympathovagal balance between patients with structurally healthy hearts who have a history of syncope and presyncope that exhibited signs or symptoms of presyncope without progressing to syncope during the tilt-table test, and a healthy group. Methodology A retrospective study was conducted on patients attending the dysautonomia clinic of a tertiary care center. Individuals of both sexes aged 15 to 50 years were included. Patients with positive tests for VVS, OH, or POTS, and those with negative results were excluded. As a healthy group, healthy volunteers without a personal history of syncope or presyncope and with a negative tilt-table test were included. Statistical Analysis Categorical variables were expressed as percentages and quantitative variables as mean ± standard deviation. Repeated measures ANOVA, the χ2 test, and effect size using Glass’s Δ were used for group comparisons. A P-value < 0.05 was considered statistically significant. The R software, RStudio, and the effsize package were used for analysis. Results The main finding was a significant decrease in cerebral blood flow secondary to an increase in cerebral vascular resistance in patients from a supine position at the start and throughout the test, compared to the control group. Conclusion The analysis of cerebral hemodynamics allows for the identification of a subpopulation of patients who exhibit decreased cerebral blood flow from a supine position during the tilt-table test while maintaining cardiovascular stability without progressing to syncope.