Low-flow aortic stenosis and preserved left ventricular ejection fraction.

Valvular aortic stenosis (AS) is the most frequent valvular disease in developed countries. Treatment decisions in AS are mainly based upon the symptomatic status of the patient and the severity of AS. Doppler echocardiography represents the standard tool for detecting and assessing the severity of the disease. Under the same denomination of severe AS [aortic valve area (AVA) < 1 cm(2)], several entities might be identified that differ in terms of trans-valvular flow rates and pressure gradients development. From a clinical standpoint, severe AS (AVA < 1 cm(2)) can be subdivided into 4 flow-gradient patterns: normal flow/low gradient (NF/LG), normal flow/high gradient (NF/HG), low flow/high gradient (LF/HG) and low flow/low gradient (LF/LG). The most commonly described entity is the paradoxical low-flow, low-gradient severe AS state, in which the stroke volume is unexpectedly reduced, despite preserved left ventricular (LV) ejection fraction. In daily practice, misdiagnosing this clinical condition might lead to an inappropriate timing of follow-up with an unnecessary delay of aortic valve replacement (AVR), which may, in turn, have a negative impact on patient outcome.