Central Illustration.

The Role of Imaging in AS Progression

Noninvasive imaging provides the ability to directly image the aortic valve and consequent pathophysiological effects on the myocardium. Imaging the valve may be performed by computed tomography (CT) to quantify aortic valve calcification (AVC) load (CT-AVC), positron emission tomography (PET) to measure calcification activity and/or echocardiography to assess hemodynamic severity. The response of the left ventricle (LV) may be assessed by echocardiographic measures of mass, ejection fraction and/or strain, whereas cardiac magnetic resonance (CMR) offers additional quantification of fibrosis. The ability of these techniques to detect therapeutic efficacy depends on the scan-rescan repeatability of the test and the rate of change of the parameter being measured. These attributes are being exploited in a number of ongoing studies to investigate novel therapies for aortic stenosis. AS = aortic stenosis; ECV = extracellular volume; iECV = indexed extracellular volume; LGE = late gadolinium enhancement; PDE5 = phosphodiesterase type 5.