Normal-Flow Low-Gradient Severe Aortic Stenosis: Myth or Reality?

ABSTRACTThe most prevalent form of “low-gradient” aortic stenosis (AS) is characterized by the concomitant presence of a small aortic valve area (<1.0 cm2) and a low mean gradient (<40 mmHg) but with preserved LV ejection fraction (≥50%) and normal flow (stroke volume index ≥ 35 mL/m2). This intriguing pattern referred to as “normal-flow, low-gradient” (NF-LG) AS is a matter of debate. Some studies suggest that this NF-LG pattern is a moderate form of AS, whereas others report that about half of these patients actually have true severe AS and thus benefit from aortic valve replacement (AVR). The purpose of this article is to provide an overview of the pathophysiology, diagnosis workup, and therapeutic management of NF-LG AS. This pattern of AS may occur as a result of normal stroke volume but reduced mean transvalvular flow rate, reduced arterial compliance and systolic hypertension, and/or incongruity in the aortic valve area and mean gradient severity cut-points. The key steps in the management of NF-LG...