[Evaluation of the sympathetic nervous system in silent ischemia with 123I-metaiodobenzylguanidine (MIBG)].

Aim: Examination of the integrity of the sympathetic nervous system in patients with angiographically proven coronary artery disease and ECG documented asymptomatic ST-segment depression.
Method: Stress and rest myocardial perfusion scintigraphy using either Thallium-201 or 99mTc-isonitrile was performed in SPECT technique in order to localize ischemia or scar associated perfusion defects. 15 min and 4 h p.i. static anterior 123I-MIBG uptake was acquired. In order to localize norepinephrine depletion 4 h p.i. additional 123I-MIBG SPECT acquisition was performed. Incidence of arrhythmias was investigated by Holter ECG. Patients with diabetes mellitus were excluded.
Results: SPECT images showed in all patients regional 123I-MIBG depletion which corresponded with scintigraphically infarcted or ischemic regions. Well perfused myocardial regions matched with regular 123I-MIBG uptake. There was no evidence of increased arrhythmias in long-term ECG.
Conclusion: The finding of regular 123I-MIBG uptake in well-perfused myocardium and infarction- or ischemia-associated regional 123I-MIBG depletion confirms that silent ischemia is not caused by a global sympathetic nervous dysfunction in a sense of cardiac polyneuropathy.