Reduced baroreflex sensitivity in situational syncope compared with vasovagal syncope: Evidence for different...

Area of Science:

• Cardiology
• Autonomic Neuroscience
• Clinical Physiology

Background:

• Baroreflex sensitivity (BRS) is crucial for short-term cardiovascular autonomic regulation and blood pressure stability.
• Adequate blood pressure stability is essential for maintaining cerebral perfusion.
• Understanding BRS differences in syncope types may clarify pathophysiology.

Purpose of the Study:

• To assess baroreflex sensitivity (BRS) in patients with situational syncope (SS).
• To compare BRS in SS patients versus vasovagal syncope (VVS) patients.
• To investigate BRS under standardized resting and orthostatic conditions.

Main Methods:

• Prospective evaluation of patients with suspected reflex syncope.
• Inclusion of patients with confirmed SS or VVS and BRS assessment.
• Propensity score matching (1:1 ratio) to balance baseline characteristics between SS and VVS groups.

Main Results:

• Matched analysis included 45 SS patients and 45 VVS patients.
• SS patients demonstrated significantly lower BRS than VVS patients at rest (5.8±2.5 vs 7.4±4.0 ms/mmHg, p=0.02).
• Reduced BRS in SS patients persisted during orthostatic stress (5.3±2.7 vs 6.8±3.4 ms/mmHg, p=0.02).

Conclusions:

• Situational syncope is characterized by reduced baroreflex sensitivity compared to vasovagal syncope.
• Distinct baroreflex profiles exist within reflex syncope subtypes.
• Findings support differentiated pathophysiological classification and personalized syncope management.