Comparison of 99Tcm-pyrophosphate 201Tl perfusion 123Ilabelled methylbranched fatty acid and sympathetic imaging in acute coronary syndrome

Among a group of patients (n=15) with acute coronary syndrome, the results of using two new myocardial radiopharmaceuticals - 123l-labelled 15-(p-iodo-phenyl)-3,R,S-methylpentadecanoic acid (BMIPP) and 123l-meta-iodobenzyl guanidine (MIBG) - were compared with dual 201Tl/99Tcm-pyrophosphate (Tl-PYP) imaging using single photon emission tomography (SPET). Defect scores were evaluated on a segment-by-segment basis for a total of 270 segments. For the 201Tl, BMIPP, and early and delayed MIBG studies, the mean (± S.D.) sums of defect scores were 9 ± 8, 18 ± 9, 22 ± 12 and 29 ± 9, respectively, revealing significantly higher scores for BMIPP and MIBG than 201Tl (P0.005). This was the case irrespective of various functional conditions, such as successful recanalization, failure of coronary angioplasty or restenosis. The culprit coronary artery was best identified using BMIPP, while MIBG SPET showed the most extensive defects. Normal perfusion with decreased BMIPP and MIBG uptake was frequently observed and associated with hypokinesis. 123I-BMIPP and MIBG are more sensitive for the detection of damaged myocardium, and the difference between perfusion and metabolism seems to reflect myocardial stunning.