Ejection fraction (EF) is a key indicator of left ventricular systolic function, representing the percentage of the end-diastolic volume that is ejected with each heartbeat. A normal left ventricular EF is 55–70%. EF is most commonly calculated on echocardiography using the modified Simpson’s biplane method, which traces the endocardial border in apical four-chamber and two-chamber views. Reduced EF (below 40%) indicates systolic heart failure and guides treatment decisions.