Early reperfusion, late reperfusion, and the open artery hypothesis: an overview

Randomized clinical trials have clearly shown the beneficial effects of early reperfusion within 12 hours, and possibly up to 24 hours, after acute myocardial infarction (AMI). The data on late reperfusion beyond 24 hours are less convincing. Many studies show that an open infarct-related artery after MI, irrespective of the initial reperfusion strategy, is independently associated with improved long-term clinical outcome. However, similar analysis of the large Global Utilization of Streptokinase and tPA for Occluded Arteries (GUSTO) 1 study did not confirm this finding. It is unclear whether mechanical reperfusion of an occluded infarct-related artery late after MI (>24 hours) in asymptomatic patients will confer long-term benefits. The late open artery hypothesis, which proposes several mechanisms by which late reperfusion may offer benefit, remains to be tested in a large clinical trial. This overview focuses on the definitions of early reperfusion, late reperfusion, the relationship between timing of reperfusion and prognosis after AMI, and the late open artery hypothesis.