Detection of angina-provoking coronary stenosis by resting iodine 123 metaiodobenzylguanidine scintigraphy in patients with unstable angina pectoris

Resting iodine 123-labeled metaiodobenzylguanidine (¹²⁵I-MIGB) scintigraphy was performed in 19 patients with unstable angina to determine if it can detect myocardial ischemia and identity the angina-provoking coronary artery. Visual assessment of ¹²³I-MIBG single-photon-emission computed tomograms was related to coronary vessel stenoses revealed by artariography at each vascular territory. Fourteen (74%) of 19 patients had regional ¹²³I-MIBG-identified defects at areas with preserved thallium-201 perfusion. ¹²³I-MIBG defects were highly positive at areas supplied by angina-provoking coronary arteries. The sensitivity and specificity of ¹²³I-MIBG defects for identifying the angina-provoking coronary vessel were 71% and 78%, respectively. The interval between the most recent angina attack and imaging was shorter and the angina occurred more commonly after admission in patients with ¹²³I-MIBG defects than in those without defects. These data suggest that repetitive myocardial ischemia impairs regional ¹²³I-MIBG uptake and that this impairment persists for several days after perfusion has been restored. Thus resting ¹²³I-MIBG scintigraphy is a useful noninvasive method to detect coronary stenoses provoking repetitive ischemia in patients with unstable angina in its acute phase.