RESUMO
Introduction: Alteration of autonomic function is the main pathophysiology of most types of syncope, including syncope due to orthostatic hypotension and neurally mediated syncope or reflex syncope. The aim of this study was to investigate the difference in autonomic dysfunction assessed between each type of syncope and to evaluate the association between the severity of autonomic dysfunction and the recurrence of syncope. Methodology: Three hundred and six participants, including 195 syncope and 109 healthy control participants, were recruited to this retrospective cohort study. Autonomic function was initially assessed by the Thai version of the Composite Autonomic Symptom Score 31 (COMPASS 31), a self-administered questionnaire. Result: According to one hundred and ninety-five syncope participants, twenty-three participants had syncope due to orthostatic hypotension, 61 had reflex syncope, 79 had presyncope, and 32 had unclassified syncope. Participants in the syncope due to orthostatic hypotension and reflex syncope groups had significantly higher COMPASS 31 scores than the control and presyncope groups, of which the syncope due to orthostatic hypotension group had the highest score. The cutoff score of 32.9 for COMPASS 31 had a sensitivity of 50.0% and a specificity of 81.9% to predict the recurrence of syncope. Conclusion: The degree of autonomic dysfunction, which was assessed by COMPASS 31, could vary depending on the syncope type. The COMPASS 31, which is an easy-to-use self-administered questionnaire utilized for the assessment of autonomic symptoms and function, was a helpful tool for classifying some types of syncope and predicting the recurrence of syncope, which could lead to appropriate further management.
