DETECTION OF ANGINA-PROVOKING CORONARY STENOSIS BY RESTING IODINE-123METAIODOBENZYLGUANIDINE SCINTIGRAPHY IN PATIENTS WITH UNSTABLE ANGINA-PECTORIS

Resting iodine 123-labeled metaiodobenzylguanidine (I-123-MIBG) scinti graphy was performed in 19 patients with unstable angina to determine if it can detect myocardial ischemia and identify the angina-provoking coronary artery. Visual assessment of I-123-MIBG single-photon-emissi on computed tomograms was related to coronary vessel stenoses revealed by arteriography at each vascular territory. Fourteen (74%) of 19 pat ients had regional I-123-MIBG-identified defects at areas with preserv ed thallium-201 perfusion. I-123-MIBG defects were highly positive at areas supplied by angina-provoking coronary arteries. The sensitivity and specificity of I-123-MIBG defects for identifying the angina-provo king coronary vessel were 71% and 78%, respectively. The interval betw een the most recent angina attack and imaging was shorter and the angi na occurred more commonly after admission in patients with I-123-MIBG defects than in those without defects. These data suggest that repetit ive myocardial ischemia impairs regional I-123-MIBG uptake and that th is impairment persists for several days after perfusion has been resto red. Thus resting I-123-MIBG scintigraphy is a useful noninvasive meth od to detect coronary stenoses provoking repetitive ischemia in patien ts with unstable angina in its acute phase.