Reperfusion revisited: beyond TIMI 3 flow

Therapy for acute myocardial infarction has advanced dramatically since the early 1980s with the use of early intravenous fibrinolytic therapy. Combining low-dose fibrinolysis and platelet lysis appears to provide an additional increase in infarct-related artery (IRA) patency, but the large-scale mortality reduction trials evaluating this strategy are just getting under way. Recently, considerable attention has shifted away from the epicardial arteries to the microvasculature. Contemporary evidence suggests that epicardial patency does not necessarily translate to actual perfusion at the myocardial level. Techniques to evaluate beyond thrombolysis in myocardial infarction (TIMI) epicardial flow are now available and validated. In addition, there are promising treatments for the prevention or alleviation of certain forms of microvascular obstruction. This review attempts to clarify the confusion surrounding epicardial flow and "myocardial malperfusion" and to provide some insight into the next direction in acute myocardial infarction therapeutics.