EARLY DIAGNOSIS OF CARDIAC INVOLVEMENT IN SYSTEMIC-SCLEROSIS BY I-123MIBG NEUROTRANSMITTER SCINTIGRAPHY

Cardiac involvement of systemic sclerosis (SSc) is associated with a p oor prognosis. Arrhythmias and conduction disturbances are a known fea ture of SSc. From histopathological examinations, it is known that the conducting system is secondarily involved as a result of focal fibros is of the myocardium. Fibrotic changes are believed to be related to v asospasms, such as Raynaud's phenomenon. The sympathetic nervous syste m is very sensitive to ischaemia, impairing the energy-dependent uptak e of intraneuronal norepinephrine. I-123-metaiodobenzylguanidine (I-12 3-MIBG) is a metabolic analogue of norepinephrine and can therefore be used as a marker of norepinephrine depletion. The aim of the study wa s to evaluate the incidence and extent of SSc-associated ischaemic dam age due to primary cardiac involvement by assessing intraneuronal I-12 3-MIBG uptake and distribution. Supplementary myocardial stress and re st perfusion scintigraphy, together with cardiological examinations (i ncluding an exercise stress test, Holter ECG and echocardiography), we re performed in 18 patients. None of the patients showed evidence of i schaemia upon myocardial perfusion stress SPET or exercise stress. ECG at rest detected pathological conductance disturbances in one patient (6%). Holter ECG evoked pathological arrhythmias in three patients (1 7%). The echocardiograms of four patients (22%) showed a slight impair ment of left ventricular diastolic function. I-123-MIBG scintigraphy r evealed an inhomogeneous reduction of norepinephrine content in 15 pat ients (83%). It would appear that I-123-MIBG scintigraphy is able to d etect cardiac SSc involvement prior to cardiological investigations. ( (C) 1998 Lippincott Williams & Wilkins).