The relation between stroke volume, which is extruded from the left ventricle and the starting end diastole filling volume gives a measure of the contractile function of the left ventricle. Each patient with known cardiovascular disease should be subject to assessment of left ventricular function by measuring ejection fraction. Several studies have demonstrated that when the ejection fraction (LVEF), which measures the ability of the heart to eject blood into the aorta, not exceed 40% (natural rate ^ 50%) increased dramatically postinfarction mortality. The ejection fraction is a reliable prognostic indicator can be calculated by ultrasonography. The reduced ejection fraction is associated with an increased risk of life-threatening arrhythmias, heart failure and death. A low ejection fraction, particularly after myocardial infarction, is a strong indication for the administration of beta-blockers, as many studies have shown that administration of these drugs significantly reduces cardiovascular mortality.