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Cardiac sympathetic dysfunction correlates with abnormal myocardial contractile reserve in dilated cardiomyopathy

Satoru Ohshima1, Satoshi Isobe, Hideo Izawa

  • 1Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan.

Journal of the American College of Cardiology
|December 6, 2005
PubMed

Insights

Iodine-123-metaiodobenzylguanidine (123I-MIBG) scintigraphy can noninvasively assess myocardial contractile reserve in dilated cardiomyopathy (DCM). Abnormal 123I-MIBG uptake correlates with impaired cardiac function and reduced SERCA2 mRNA levels in DCM patients.

Area of Science:

  • Cardiology
  • Nuclear Medicine
  • Molecular Biology

Background:

  • The relationship between cardiac sympathetic nervous function and myocardial contractile reserve in dilated cardiomyopathy (DCM) is not well understood.
  • Investigating this link can improve understanding of DCM pathophysiology.

Purpose of the Study:

  • To investigate the relationship between iodine-123-metaiodobenzylguanidine (123I-MIBG) findings and myocardial contractile reserve in patients with mild to moderate DCM.
  • To explore the association between 123I-MIBG uptake and molecular markers of cardiac function.

Main Methods:

  • Twenty-four DCM patients underwent echocardiography, biventricular catheterization, and 123I-MIBG scintigraphy.
  • Myocardial contractile function (LV dP/dt(max)) was assessed at rest and during atrial pacing.
  • Messenger RNA (mRNA) expressions of intracellular Ca2+-regulatory proteins, including SERCA2, were analyzed.

Main Results:

  • A significant correlation was found between delayed 123I-MIBG heart-mediastinum ratio (HMR) and the percentage change in LV dP/dt(max) (r = 0.64; p < 0.001).
  • Delayed 123I-MIBG HMR was lower in patients with worsening LV dP/dt(max) changes.
  • Reduced maximum LV dP/dt(max) and SERCA2 mRNA levels were observed in patients with lower delayed HMR values.

Conclusions:

  • Abnormal myocardial 123I-MIBG accumulation is linked to impaired myocardial contractile reserve and down-regulation of SERCA2 mRNA in DCM.
  • Myocardial 123I-MIBG scintigraphy serves as a valuable noninvasive tool for evaluating myocardial contractile reserve in mild to moderate DCM.
Abstract

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