*4.1.2 B blockers*

During the first hours of AMI, the B blockers can decrease the demand for O2 by the myocardium by decreasing heart rate, blood pressure, and contractility and, additionally, by prolonging diastole, can improve ischemic myocardial perfusion, mainly of the subendocardium. As a consequence of this, B blockers can reduce the size of the AMI. Based on the clinical evidence provided by the ISIS I, MIAMI, TIMI II, and Taste I trials, the use of B blockers early, in the absence of contraindications, may offer benefits from the first day and in a sustained way avoiding around 6 deaths per 1000 patients treated. B oral blockers have class I indication level of evidence A, and in the form of intravenous administration, they have class IIa indication with level of evidence B [55–57].
