Technetium 99m sestamibi in the assessment of acute myocardial infarction.

Technetium 99m sestamibi is a promising new radiopharmaceutical that can assess myocardium at risk, infarct size, and treatment efficacy in acute myocardial infarction. The minimal redistribution of this radiopharmaceutical makes it ideal for the measurement of myocardium at risk, as demonstrated by several animal studies. The high-count density images are readily quantitated, and techniques have been developed and validated for this purpose. Early clinical studies have shown that myocardium at risk varies widely, even for a coronary occlusion in a similar location, a finding similar to that reported previously in several different animal infarction models. The clinical use of this radiopharmaceutical to measure final infarct size and treatment benefit, or myocardial salvage, has now been demonstrated using both planar and tomographic imaging techniques. Evidence of benefit is often evident by 18 to 48 hours after reperfusion therapy, although the full extent of improvement is not evident until later. The current 6-hour shelf life and 30-minute preparation time are logistical barriers to widespread clinical use. This radiopharmaceutical provides a new, powerful measurement tool for the assessment of treatment efficacy in acute myocardial infarction that is probably superior to other currently available methods.