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Cardiac adrenergic nerve function and microvascular dysfunction in patients with cardiac syndrome X

A Di Monaco1, I Bruno, A Sestito

  • 1Istituto di Cardiologia, Università Cattolica del Sacro Cuore, Roma, Italy.

Heart (British Cardiac Society)
|January 24, 2009
PubMed

Insights

Cardiac MIBG uptake abnormalities and coronary microvascular dysfunction are common in cardiac syndrome X (CSX). However, this study found no correlation between these cardiac MIBG defects and impaired coronary flow response in CSX patients.

Area of Science:

  • Cardiology
  • Nuclear Medicine
  • Cardiovascular Imaging

Background:

  • Cardiac Syndrome X (CSX) is characterized by chest pain despite normal coronary angiograms.
  • Coronary microvascular dysfunction (CMD) is increasingly recognized as a key feature of CSX.
  • The role of cardiac autonomic dysfunction in CSX is not fully understood.

Purpose of the Study:

  • To investigate the relationship between cardiac adrenergic nerve function, assessed by (123)I-metaiodobenzylguanidine (MIBG) scintigraphy, and coronary microvascular dysfunction in patients with CSX.
  • To determine if MIBG uptake abnormalities correlate with impaired coronary flow reserve in CSX.

Main Methods:

  • A case-control study involving 29 patients with CSX and 20 healthy controls.
  • Myocardial scintigraphy using (123)I-metaiodobenzylguanidine (MIBG) planar and SPECT imaging.
  • Coronary flow response (CFR) to adenosine and cold pressor test (CPT) assessed by transthoracic Doppler echocardiography in the LAD coronary artery.

Main Results:

  • 86.2% of CSX patients exhibited abnormal cardiac MIBG uptake compared to none of the controls (p<0.001).
  • CSX patients had significantly lower heart/mediastinum (H/M) MIBG uptake ratio and higher defect scores than controls (p<0.001 and p=0.002, respectively).
  • Coronary flow response to both adenosine and CPT was significantly reduced in CSX patients compared to controls (p<0.001 for both).
  • No significant correlation was found between MIBG uptake parameters (H/M ratio, defect score) and CFR to adenosine or CPT in CSX patients (p>0.05 for all).

Conclusions:

  • Patients with CSX demonstrate significant abnormalities in both cardiac adrenergic nerve function and coronary microvascular function.
  • Despite the presence of both abnormalities, no direct correlation was identified between MIBG uptake defects and impaired coronary microvascular function in this CSX cohort.
  • Further research is warranted to elucidate the underlying mechanisms and the clinical significance of MIBG defects in CSX.
Abstract

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