Reduced coronary flow reserve and parasympathetic dysfunction in patients with cardiovascular syndrome X

Area of Science:

• Cardiology
• Autonomic Nervous System Function

Background:

• Cardiovascular syndrome X, also known as cardiac syndrome X, is a condition characterized by chest pain despite normal coronary angiograms.
• The underlying causes of syndrome X remain unclear, with research exploring autonomic dysfunction and coronary flow reserve.
• Investigating the link between parasympathetic dysfunction and impaired coronary flow reserve is crucial for understanding syndrome X pathophysiology.

Purpose of the Study:

• To investigate the correlation between parasympathetic nervous system dysfunction and reduced coronary flow reserve in women with cardiovascular syndrome X.
• To determine if vagal impairment is associated with diminished coronary blood flow in these patients.

Main Methods:

• Eleven women diagnosed with cardiovascular syndrome X were evaluated.
• Autonomic function was assessed using heart rate and blood pressure variability analysis and the cold face test.
• Coronary flow reserve was noninvasively measured using transthoracic echocardiography.
• Patients were compared with healthy volunteers.

Main Results:

• Over half of the patients (64%) exhibited vagal impairment, indicated by heart rate/blood pressure variability and cold face test results.
• Patients with vagal impairment showed significantly reduced mean and maximal diastolic coronary velocity reserves compared to controls and syndrome X patients without vagal impairment.
• A significant difference in coronary velocity reserves was observed across groups (P=0.0005 for mean, P=0.0047 for maximal).

Conclusions:

• Cardiovascular syndrome X patients are a heterogeneous group.
• Vagal dysfunction is present in a significant proportion of syndrome X patients.
• Impaired coronary flow reserve is associated with vagal dysfunction in syndrome X, suggesting a role for parasympathetic impairment in the condition's development.