Background: The abnormal neural regulation of the heart is one of the most important pathogenesis of cardiac syndrome X (CSX). The aim the study was to evaluate changes in autonomic nervous system activity (ANS) in CSX patients.
Methods: Forty-two patients (age 46 +/- 9 years) with CSX and forty-two healthy volunteers (age 47 +/- 9 years) as a control group were included in the study. Function of ANS was estimated with non-invasive tests based on simple cardiovascular reflexes.
Results: In 50% of CSX patients was diminished response to parasympathetic stimulation in deep breathing test. In response to sympathetic stimulation (the changes in body position, hand grip test) was observed decreased 30/15 ratios. The cardiac autonomic activities were altered with parasympathetic withdrawal and/or sympathetic abnormality in patients with CSX.
Conclusions: The population of CSX patients is heterogeneous with normal autonomic system (about 23% of population) and abnormal ANS activity (about 77% patients). In cardiac syndrome X patients selected tests of ANS indicated presence of disturbances in sympathetic-parasympathetic balance.