Recovery of the cardiac adrenergic nervous system after long-term beta-blocker therapy in idiopathic dilated cardiomyopathy: assessment by increase in myocardial 123I-metaiodobenzylguanidine uptake

J Nucl Med. 2001 Jan;42(1):49-54.


In chronic heart failure, elevated plasma norepinephrine (NE) levels and a disparity between the neuronal release and the effective reuptake of NE lead to an increased concentration of NE in the presynaptic cleft, causing a downregulation of the myocardial beta-adrenoceptors. The clinical and prognostic effectiveness of beta-blocker therapy has been shown in patients with chronic heart failure in several large trials. The purpose of this study was to investigate the effect of long-term beta-blocker therapy on the cardiac adrenergic nervous system as assessed by the myocardial uptake of 123I-metaiodobenzylguanidine (MIBG), an analog of NE, in idiopathic dilated cardiomyopathy (IDC).

Methods: In 10 patients with IDC and stable chronic heart failure the myocardial MIBG uptake was measured at baseline and at 1 y (median, 11.5 mo) after treatment with beta-blockers (metoprolol, n = 5; bisoprolol, n = 1; and carvedilol, n = 4) in addition to standard medication. In parallel with the changes in MIBG uptake, the New York Heart Association functional class, the left ventricular ejection fraction (LVEF), and the left ventricular end-diastolic diameter (LVEDD) were documented before and after 1 y of therapy with beta-blockers.

Results: During the 1-y follow-up, a significant increase in myocardial 123I-MIBG uptake (P = 0.005) in parallel with an improved LVEF (P = 0.005) and a reduced LVEDD (P = 0.019) was found. A trend toward an improvement of the New York Heart Association functional class under the beta-blocker therapy (P = 0.139) was also found.

Conclusion: Assessment of the myocardial 123I-MIBG uptake is a useful noninvasive tool for evaluating changes in cardiac sympathetic nerve activity under medical therapy. Long-term treatment with beta-blockers in IDC causes a recovery of the cardiac adrenergic nervous system concomitantly with a clinical and hemodynamic improvement.

MeSH terms

  • 3-Iodobenzylguanidine*
  • Adrenergic beta-Antagonists / therapeutic use*
  • Cardiomyopathy, Dilated / diagnostic imaging*
  • Cardiomyopathy, Dilated / drug therapy*
  • Female
  • Follow-Up Studies
  • Heart / diagnostic imaging
  • Heart / innervation*
  • Humans
  • Iodine Radioisotopes*
  • Male
  • Middle Aged
  • Myocardium / metabolism
  • Prospective Studies
  • Radiopharmaceuticals
  • Sympathetic Nervous System / physiopathology*
  • Technetium Tc 99m Sestamibi
  • Time Factors
  • Tomography, Emission-Computed, Single-Photon


  • Adrenergic beta-Antagonists
  • Iodine Radioisotopes
  • Radiopharmaceuticals
  • 3-Iodobenzylguanidine
  • Technetium Tc 99m Sestamibi