Aortic Valve Calcium Load
Diagnostic and Prognostic Implications in Aortic Stenosis
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In aortic stenosis (AS), patient management is highly dependent on the accurate evaluation of AS severity. A mean transvalvular pressure gradient ≥40 mm Hg, peak aortic jet velocity ≥4 m/s, and an aortic valve area <1.0 cm2 measured with echocardiography reflect severe AS.1–3 In the majority of patients with severe AS, these criteria are always present. However, up to 30% of patients with severe AS may show an aortic valve area <1.0 cm2 despite a low mean transvalvular pressure gradient (<40 mm Hg).4 This low-gradient severe AS is often the consequence of a low-flow state that may be a result of impaired left ventricular (LV) systolic function (ejection fraction <50%, so-called classical low-flow low-gradient severe AS) or in the setting of severe LV hypertrophy with normal LV ejection fraction (≥50%) and a small LV cavity (paradoxical low-flow low-gradient severe AS).4 In patients with classical low-flow low-gradient severe AS, the question is whether the aortic valve does not open because of degenerative (calcific) changes (true severe AS) or because the dysfunctional LV is unable to generate enough stroke volume to open the valve (pseudosevere AS). By increasing LV contractility with low-dose dobutamine infusion, Doppler-echocardiography can demonstrate a >20% increase in stroke …