Analysis and Comparative Evaluation of Aortic Calcium by Computed Tomography and Histopathology in Patients With Aortic Stenosis

1. Title

Analysis and comparative evaluation of aortic calcium by computed tomography and histopathology in patients with aortic stenosis. 2. Background.

Calcified aortic valve disease (CAVD) was initially considered to be a passive degeneration of the extracellular matrix (EM). Recent studies have shown that within the development of the damage mechanism there is complexity and it is an active (1) and degenerative process where genetic, environmental and epigenetic phases overlap and interact leading to hemodynamic changes in blood flow, endothelial dysfunction and metabolic disorders that lead to low-density lipoprotein cholesterol deposits in the ME where at the same time there is an underlying infiltration of macrophages, oxidative stress, and release of pro-inflammatory cytokines. (2) However, although there are several theories of damage, and some of them are attributed to a diversity of origin such as genetic, congenital, infectious, and degenerative. Finally, the dynamic and functional impact of the heart affects equally. It leads to organic deterioration when the AD reaches clinical and echocardiographic criteria of severity, and the only therapeutic option is the change or replacement of the aortic valve.

The participation of imaging methods such as computerized tomography about to the concerning the aortic valve through the measurement of the aortic calcium score (AVC-CT) as a method to determine the severity of aortic stenosis (AS) in those cases where echocardiographic measurements are conflicting, allows us to see the interest in defining this problem through different angles of investigation (7). In AD, progressive calcification is the trigger factor that also predominantly leads to aortic valve obstruction. (3) Currently, such calcification can be easily quantified using the same acquisition protocol and Agatston Scoring Method as used for a coronary artery calcium scan and is particularly attractive because it provides an assessment of the severity of AD, which is independent of the geometry and ventricular ejection fraction. Advances in the field of CT CVA measurement have been demonstrated in the last decade and are closely associated with hemodynamic measurements of moderate to severe AD in Doppler echocardiography, however, until recently, significant over-positioning of calcium from the aortic valve area among patients with hemodynamically severe AD and those with non-severe AD made it challenging to implement in clinical practice.

This development has generated significant interest in the use of CT-CVA as an alternative and complementary assessment of the severity of AD, especially in patients with discordant echocardiographic findings. (11) In fact: 1) CVA is strongly but non-linearly associated with hemodynamic measures of severity in moderate to severe AD (12). Thus, the determination of CVA may help discriminate severe AD from non-severe AD in patients with discordant findings measured by echocardiography, and 3) in patients with moderate to severe AD, CVA is also likely associated with faster progression of AD and with survival. However, it should be mentioned that the analysis of that series did not make adjustments to the calcium measured in the patients' coronary artery. Although the CVA score has been recommended in the European Society of Cardiology Guidelines to confirm the severity of AD in the following conditions 1) patients with low left ventricular ejection fraction (LVEF), gradient and low flow, in which dobutamine stress echocardiography is inconclusive and 2) patients with low gradient AD and preserved LVEF, and this is not yet part of the American Heart Association (AHA) and American College of Cardiology (ACC) guidelines (13).