Tracing ischemic memory by metabolic pathways: BMIPP and beyond

Myocardial ischemia (MI) resulting in infarction is an important cause of mortality and morbidity worldwide. Acute ischaemia rapidly impairs myocardial contractile function. Myocardial dysfunction persisting for several hours after transient non-lethal ischaemia, eventually resulting in full functional recovery is termed as myocardial stunning. Hibernation is now thought to be the consequence of repetitive bouts of ischaemia and stunning due to normally occurring increases in myocardial metabolic demand in the setting of significant coronary stenoses.We need robust investigations to identify and treat MI early. Myocardial perfusion imaging has established itself as the earliest investigation that can identify ischemia with or without infarction in an acute setting. However, recent data reveals that metabolic changes precede perfusion abnormalities during an ischemic or infarction episode; thus the renewed interest in the myocardial metabolic imaging. Concept of myocardial metabolic imaging is gaining momentum with the wider availability of positron emitting radio isotopes. Myocardial metabolism has been widely studied using 123I-BMIPP [15-(p-Iodophenyl)-3-methylpentadecanoic acid] and BMIPP was synonymous for ischemic memory imaging, (IMI). It was based on the fact that one can capture the still picture of the ongoing ischemic insult as a memory image past the acute episode. BMIPP imaging was primarily based on its ability to memorize the area at risk for a couple of weeks, even after reperfusion therapy. We aim to elaborate in this review the various radiotracers that can be used to identify myocardial metabolic disorders at its inception so that it may be possible to provide early management options.

Keywords:

Ischemic memory , BMIPP , 18F-FDG PET , 99mTc Labelled-Annexin , SPECT , Hibernation , Molecular probes