Importance of TIMI 3 flow.

Since the advent of reperfusion therapy for acute ST elevation myocardial infarction, the “open artery hypothesis” proposed that benefit is achieved from early reperfusion of the occluded coronary artery, which limits the size of infarction, reduces the degree of left ventricular dysfunction, and improves survival.1 After numerous studies confirmed the benefit of a patent infarct-related artery, more careful examination of the degree of reperfusion was performed using the Thrombolysis in Myocardial Infarction (TIMI) flow grading system devised in the TIMI 1 trial.2 When differentiating apparently normal TIMI grade 3 flow from more delayed TIMI grade 2 flow in patent arteries, greater myocardial salvage and improved survival were observed in patients who achieved TIMI grade 3 flow.3,4 There is a nearly linear correlation between higher rates of early TIMI grade 3 flow and improved survival, regardless of whether reperfusion is achieved with thrombolysis or primary percutaneous coronary intervention (PCI).4