Discordant iodine-123 metaiodobenzylguanidine uptake area reflects recovery time dispersion in acute myocardial infarction

Iodine-123 metaiodobenzylguanidine (MIBG) uptake was reported to be reduced compared to Tl-201 (Tl) in acute myocardial infarction (AMI). Within such an area, degrees of both sympathetic neural function and ischemic myocardia l cell damage arc considered to be greatly dispersed. These kinds of damage were reported to effect reporalization time in myocardial cells, and we ev aluated our hypothesis that extension of the discordant MIBG uptake area co rrelates with recovery time (RT) dispersion and relate ventricular arrhythm ias in AMI. MIBG and Tl images were obtained in AMI patients. Regional Tl o r MIBG uptake was estimated in 9 segments of SPECT by using four-point scor ing. The total score was the sum of scores in 9 SPECT segments. Delta Tl-MI BG was calculated by subtracting the total MIBG score from the total Tl sco re. Corrected RT (RTc) was measured as a signal-averaged ECG. RTc dispersio n was defined as the difference between maximal and minimal RTc. The patien ts were assigned to two groups (group A; less than or equal to Lown 4a, gro up B; greater than or equal to Lown 4b) according to the results of 24-hour Holter monitoring. A positive correlation between RTc dispersion and Delta Tl-MIBG was found. Delta Tl-MIBG and RTc dispersion in group B were greate r than those in group A. These results suggested that Delta Tl-MIBG could b e used to predict the development of malignant ventricular arrhythmias.