The last 2 decades have witnessed a revolution in acute reperfusion
therapy for ST-segment elevation myocardial infarction (STEMI). This therapy
has focused on patients who present within the first 12 hours of infarction,
in the belief that the benefit of therapy is minimal after that time. However,
a significant minority of patients present with STEMI more than 12 hours after
the onset of chest pain. In 2 large registry studies,1,2 patients
presenting after 12 hours represented 8.5% and 31.3% of all patients with
STEMI. Available randomized trial evidence has until now suggested little
role for acute reperfusion therapy in this setting. The Fibrinolytic Therapy
Trialist Collaboration3 reported that mortality
was not reduced by thrombolytic therapy in patients presenting after 12 hours.
Based on these data, existing clinical practice guidelines4,5 strongly
favor the use of acute reperfusion therapy in patients presenting within 12
hours but are more cautious about the potential value of reperfusion therapy
in patients presenting later than 12 hours. However, the lack of benefit may,
in part, be due to the inability of thrombolytic drugs to restore patency
in vessels that have been occluded for several hours.6