NORADRENALINE DEPLETION IN PATIENTS WITH CORONARY-ARTERY DISEASE BEFORE AND AFTER PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY WITH I-123METAIODOBENZYLGUANIDINE AND SINGLE-PHOTON EMISSION TOMOGRAPHY

Iodine-123 metaiodobenzylguanidine (MIBG) is a noradrenaline analogue which can be used as a tracer to investigate the cardiac sympathetic n ervous system. Regional ischaemia leads to noradrenaline depletion wit h functional denervation which can be demonstrated by reduced MIBG upt ake. In order to evaluate the reversibility of ischaemia-associated da mage to the sympathetic nervous system, neuronal scintigraphy with I-1 23-MIBG and myocardial rest and stress perfusion scintigraphy with tec hnetium-99m sestamibi was performed in 16 patients with coronary arter y disease before and 3-4 months after percutaneous transluminal corona ry angioplasty (PTCA). Partial re-innervation ocurred in five patients , the degree of stenosis of remaining lesions being estimated by repea t angiography to be below 40%. Unchanged MIBG defects cold be confirme d in four patients with residual lesions of between 40% and 50%. Incre ased MIBG defects were shown in three patients with significant resten oses of more than 70%. In all patients the neuronal defects exceeded t he ischaemia-induced or scar-associated perfusion defects. Three patie nts dropped out of this study: one for technical reasons, one due to e mergency aortocoronary bypass surgery and one due to diabetic polyneur opathy. This investigation shows that the sympathetic nervous system i s highly sensitive to ischaemia. Further studies need to be done to as sess the conditions allowing re-innervation after PTCA.