Low-gradient ‘severe’ aortic stenosis with preserved ejection fraction: new entity, or discrepant definitions?

Surgery of aortic valve stenosis (AS) is often dependent on whether stenosis is considered severe, as defined by aortic valve area (AVA) and/or mean pressure gradient (dPm) criteria set forth by the American College of Cardiology/American Heart Association and the European Society of Cardiology. Problems arise in determining whether AS is severe in patients with normal left-ventricular (LV) function who meet either an AVA criterion or a dPm criterion but not the other, especially in patients with low-gradient 'severe' AS (dPm ≤ 40 mmHg, AVA < 1.0 cm2). This article considers whether low-gradient 'severe' AS with preserved ejection fraction (EF) is a new entity or merely an example of discrepant or inconsistent criteria for defining severe AS.