Young Women Face Highest Risk of Cardioinhibitory Vasovagal Syncope in Tilt Testing Study

Young women appear to be at the highest risk of the cardioinhibitory subtype of vasovagal syncope, according to a large retrospective analysis of more than 3,000 patients who underwent head-up tilt testing at a single Chinese hospital. The study, published in BMC Cardiovascular Disorders, examined how age, gender and hypertension relate to the three hemodynamic subtypes of vasovagal syncope identified during tilt testing.

Researchers led by Zimo Liu and Yan Li reviewed records from 3,084 consecutive patients with suspected reflex syncope who had undergone head-up tilt testing following the Italian protocol at Yantai Yuhuangding Hospital.

Head-up tilt testing is an established diagnostic tool for vasovagal syncope, a common form of reflex fainting. During the test, patients are tilted upright, and in some protocols a drug such as nitroglycerin is added to provoke a response.

The analysis found significant differences in the distribution of the three subtypes across four age groups, with the authors reporting a P value below 0.001. The gender ratio also differed significantly between the passive phase of the test and the phase enhanced with trinitroglycerin for all subtypes, again with P values below 0.001. Only about 10 percent of tilt-test-positive vasovagal syncope cases were provoked during the passive phase alone, underscoring how often the drug-enhanced phase was needed to elicit a positive response.

To characterize how risk changed with age, the researchers used restricted cubic spline analysis, a statistical technique that can reveal nonlinear relationships. In the passive phase, after adjusting for hypertension, this analysis showed a nonlinear association between age and the risk of the mixed and cardioinhibitory subtypes. The mixed subtype followed a J-shaped pattern and was more common in women, with an adjusted odds ratio of 2.44 for females, while the vasodepressor subtype showed a linear relationship with age.

During the trinitroglycerin-enhanced phase, all three subtypes displayed nonlinear age-risk associations. Both the mixed and cardioinhibitory subtypes followed a J-shaped pattern, with adjusted odds ratios for females of 2.265 and 2.557 respectively, while the vasodepressor subtype showed a U-shaped distribution across age. These patterns suggest that the youngest and oldest patients carried elevated risk for certain subtypes, with young women standing out for the cardioinhibitory form.

Hypertension showed a consistent negative association with all three subtypes during the drug-enhanced phase. The adjusted odds ratios were 0.420 for the mixed subtype, 0.502 for the cardioinhibitory subtype and 0.326 for the vasodepressor subtype. The authors also reported significant interactions between hypertension and age for the mixed and cardioinhibitory subtypes, with P values for interaction below 0.05, indicating that the apparent protective association of hypertension changed with age.

The authors conclude that the study revealed nonlinear risk patterns of vasovagal syncope subtypes in relation to age, gender and hypertension, and they recommend subtype-based stratified assessment for personalized prevention and intervention. As a retrospective, single-center study of Chinese patients tested with one protocol, the findings describe associations observed in this population and require confirmation in other settings before broader conclusions can be drawn.

Subject of Research: Demographic patterns of vasovagal syncope subtypes identified by head-up tilt testing

Article Title: Demographic features of vasovagal syncope subtypes identified by head-up tilt testing: a 10-year cross-sectional study of 3084 cases

Article References: Liu, Z., & Li, Y. (2026). Demographic features of vasovagal syncope subtypes identified by head-up tilt testing: a 10-year cross-sectional study of 3084 cases. BMC Cardiovascular Disorders. https://doi.org/10.1186/s12872-026-06863-w

Image Credits: AI Generated

DOI: 10.1186/s12872-026-06863-w

Keywords: vasovagal syncope, head-up tilt test, cardioinhibitory subtype, vasodepressor subtype, mixed subtype, hypertension, age, gender differences, reflex syncope, retrospective study, nitroglycerin-enhanced phase, restricted cubic splines