E/A Ratio

Echocardiographic phases of ventricular filling have been described as early (E) and late, or atrial (A). The latter is of course dependent upon atrial contraction and therefore is absent in atrial fibrillation. Characteristically, when diastolic dysfunction is present, a greater portion of end-diastolic volume is the result of late filling rather than early filling. Thus the E/A ratio is reduced in diastolic dysfunction.