Imaging of low-gradient severe aortic stenosis.

Although most patients with severe aortic stenosis (AS) have high peak velocity and mean transvalvular gradient, there is a subset of patients with low-flow, low-gradient severe AS (LGSAS). Assessment and management of such patients can be difficult and dobutamine echocardiography has been recommended to distinguish those with pseudo-AS (low calculated AVA due to insufficient flow to fully open the valve) from those with contractile reserve and true LGSAS, who may have good outcomes with surgery. More recently, a group of patients with LGSAS and preserved LV function have been identified. These patients are often elderly with hypertension, small left ventricular cavities, and concentric left ventricular hypertrophy. Because cardiac imaging plays a vital role in hemodynamic classification of patients with suspected LGSAS and determining appropriate management, this review was undertaken to summarize the current state of knowledge of this important but complex condition.