Abstract 12227: New Insights Into Calcification and Aortic Stenosis Using 4-dimensional Computed Tomography.

Abstract

Background: Aortic Valve Calcification (AVC) is intrinsic to aortic stenosis (AS). While established concepts assume homogeneous calcification causing AS, wide variability in hemodynamic severity at any given AVC burden suggests other operative mechanisms. Multidetector computed tomography (MDCT) now accurately measures global AVC, but AVC spatial distribution remains elusive due to imaging orientation. Methods and Results: We developed ‘en-face’ imaging by re-registration of 4D-MDCT to quantify AVC spatial distribution and analyzed global AVC load and AVC distribution in 418 patients with AS (76±9 years; mean gradient 35±17 mmHg). 4D-volume-rendered MDCT datasets were re-oriented to en-face view of aortic valve for AVC spatial scoring with individual cusp calcification load, cusp-edge calcification and AVC asymmetry. Despite high total AVC load (450 [250-666] AU/cm 2 ), asymmetry was frequent (50%), with a difference between most- and least-calcified cusp of 112 [66-182] AU/cm 2 . Maximum AVC was in the non-coronary cusp in 61% (p<0.001). Cusp edge calcification was none-mild in 26%, moderate in 62% and severe in 12%. Adjusting for total AVC, severe AS (mean gradient >40 mmHg) was more likely with symmetrical AVC (odds ratio [OR] 2.36, p<0.001) and with edge calcification moderate (OR 4.16, p=0.001 vs none-mild) to severe (OR 10.7, p=0.001). Inclusion of AVC distribution improved models predicting AS severity over total AVC (p<0.001). Conclusions: Four-dimensional MDCT en-face re-registration and AVC quantitation provides new insight into AS pathophysiology. Contrary to classical concepts, AVC is frequently inhomogeneous and asymmetric. Hemodynamic AS severity is independently affected not only by global AVC but also by variations in AVC distribution and location within cusps, emphasizing the importance of 4D AVC assessment in AS. Impact of quantified AVC asymmetry and location on outcome of transcutaneous aortic valve replacement should be evaluated.