title: Low-gradient aortic stenosis.
abstract: An important proportion of patients with aortic stenosis (AS) have a 'low-gradient' AS, i.e. a small aortic valve area (AVA <1.0 cm(2)) consistent with severe AS but a low mean transvalvular gradient (<40 mmHg) consistent with non-severe AS. The management of this subset of patients is particularly challenging because the AVA-gradient discrepancy raises uncertainty about the actual stenosis severity and thus about the indication for aortic valve replacement (AVR) if the patient has symptoms and/or left ventricular (LV) systolic dysfunction. The most frequent cause of low-gradient (LG) AS is the presence of a low LV outflow state, which may occur with reduced left ventricular ejection fraction (LVEF), i.e. classical low-flow, low-gradient (LF-LG), or preserved LVEF, i.e. paradoxical LF-LG. Furthermore, a substantial proportion of patients with AS may have a normal-flow, low-gradient (NF-LG) AS: i.e. a small AVA-low-gradient combination but with a normal flow. One of the most important clinical challenges in these three categories of patients with LG AS (classical LF-LG, paradoxical LF-LG, and NF-LG) is to differentiate a true-severe AS that generally benefits from AVR vs. a pseudo-severe AS that should be managed conservatively. A low-dose dobutamine stress echocardiography may be used for this purpose in patients with classical LF-LG AS, whereas aortic valve calcium scoring by multi-detector computed tomography is the preferred modality in those with paradoxical LF-LG or NF-LG AS. Although patients with LF-LG severe AS have worse outcomes than those with high-gradient AS following AVR, they nonetheless display an important survival benefit with this intervention. Some studies suggest that transcatheter AVR may be superior to surgical AVR in patients with LF-LG AS.
authors.affiliation: Québec Heart and Lung Institute/Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, 2725 Chemin Sainte Foy, #A-2075, QC, Canada G1V4G5.
authors.forename: Marie-Annick
authors.initials: MA
authors.lastname: Clavel
authors.affiliation: CHU Limoges, Hôpital Dupuytren, Faculté de médecine de Limoges, Limoge, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Magne
authors.affiliation: Québec Heart and Lung Institute/Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, 2725 Chemin Sainte Foy, #A-2075, QC, Canada G1V4G5 philippe.pibarot@med.ulaval.ca.
authors.forename: Philippe
authors.initials: P
authors.lastname: Pibarot
mesh_terms: D001021:Aortic Valve; D001024:Aortic Valve Stenosis; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D012720:Severity of Illness Index; D013318:Stroke Volume; D016896:Treatment Outcome
keywords: Aortic stenosis; Aortic valve replacement; Computed tomography; Echocardiography; Low flow; Low gradient; Transcatheter aortic valve replacement