A New Approach to the Etiology of Syncope: Infection as a Cause.

Background/objectives: Syncope is a common clinical occurrence, with neurally mediated and orthostatic types accounting for about 75% of cases. The exact pathophysiological mechanisms remain unclear, with recent evidence suggesting autonomic nervous system damage and a potential infectious etiology. This study aimed to examine the role of infection in the development of syncope and orthostatic hypotension (OH).

Methods: The cross-sectional study included 806 patients from the Neurocardiological Laboratory of the Institute for Cardiovascular Diseases "Dedinje". Patients were divided into three groups: unexplained recurrent syncope (n = 506), syncope with OH during the head-up tilt test (HUTT) (n = 235), and OH without a history of syncope (n = 62). All participants underwent the HUTT, and 495 underwent serological testing for various microorganisms. Data were analyzed using chi-squared tests and binary and multinomial logistic regression.

Results: The HUTT was positive in 90.6% of patients with syncope and OH, compared with 61.6% with syncope alone (p < 0.001). Serological testing revealed that 57.85% of syncope patients, 62.9% of syncope with OH patients, and 78% of OH patients had positive IgM antibodies to at least one microorganism. Multivariate analysis indicated that IgM antibodies to Coxsackievirus and Epstein-Barr virus were significant predictors of OH.

Conclusions: This study demonstrated a potential association between infections and syncope/OH. Further investigation into the role of infectious agents in autonomic dysfunction is warranted to clarify the underlying mechanisms of syncope and OH.