- The left atrium fulfills three major physiologic roles that influence LV filling and performance.
- acts as a contractile pump that delivers 15% to 30% of the entire LV filling,
- reservoir that collects pulmonary venous return during ventricular systole, and
- conduit for the passage of stored blood from the left atrium to the left ventricle during early ventricular diastole.
- Increased LA size
- In the absence of mitral valve disease, an increase in LA size most commonly reflects increased wall tension as a result of increased LA pressure, as well as impairment in LA function secondary to an atrial myopathy.
- A clear relationship exists between an enlarged left atrium and the incidence of atrial fibrillation and stroke, risk for overall mortality after myocardial infarction, risk for death and hospitalization in patients with dilated cardiomyopathy, and major cardiac events or death in patients with diabetes mellitus.
- LA enlargement is a marker of both the severity and chronicity of diastolic dysfunction and magnitude of LA pressure elevation.