Cardiac Imaging for Assessing Low-Gradient Severe Aortic Stenosis.
Up to 40% of patients with aortic stenosis (AS) harbor discordant Doppler-echocardiographic findings, the most common of which is the presence of a small aortic valve area (≤1.0 cm2) suggesting severe AS, but a low gradient (<40 mm Hg) suggesting nonsevere AS. The purpose of this paper is to present the role of multimodality imaging in the diagnostic and therapeutic management of this challenging entity referred to as low-gradient AS. Doppler-echocardiography is critical to determine the subtype of low-gradient AS: that is, classical low-flow, paradoxical low-flow, or normal-flow. Patients with low-flow, low-gradient AS generally have a worse prognosis compared with patients with high-gradient or with normal-flow, low-gradient AS. Patients with low-gradient AS and evidence of severe AS benefit from aortic valve replacement (AVR). However, confirmation of the presence of severe AS is particularly challenging in these patients and requires a multimodality imaging approach including low-dose dobutamine stress echocardiography and aortic valve calcium scoring by multidetector computed tomography. Transcatheter AVR using a transfemoral approach may be superior to surgical AVR in patients with low-flow, low-gradient AS. Further studies are needed to confirm the best valve replacement procedure and prosthetic valve for each category of low-gradient AS and to identify patients with low-gradient AS in whom AVR is likely to be futile.
Institut Universitaire de Cardiologie et de Pneumologie de Québec (Québec Heart and Lung Institute), Laval University, Québec, Québec, Canada.
Marie-Annick
MA
Clavel
University of Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada.
Ian G
IG
Burwash
Institut Universitaire de Cardiologie et de Pneumologie de Québec (Québec Heart and Lung Institute), Laval University, Québec, Québec, Canada. Electronic address: philippe.pibarot@med.ulaval.ca.
Philippe
P
Pibarot
D001021:Aortic Valve / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D057791:Cardiac Imaging Techniques; D015150:Echocardiography, Doppler; D025401:Echocardiography, Stress; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000295:instrumentation; D006439:Hemodynamics; D006801:Humans; D061330:Multidetector Computed Tomography; D011237:Predictive Value of Tests; D011379:Prognosis; D011474:Prosthesis Design; D012720:Severity of Illness Index; D013318:Stroke Volume; D016277:Ventricular Function, Left
aortic stenosis; computed tomography; echocardiography; low flow; low-gradient