CT imaging of periaortic valve adipose tissue: clinical implication to evaluate severity of aortic stenosis

Introduction Aortic stenosis (AS) represents a substantial and increasing disease burden in the aging population. Pathophysiologically, atherogenic stimuli has been considered to promote the formation and progression of aortic stenosis. Several mechanistic studies reported inflammation as a potential driver causing aortic stenosis. However, the association of inflammation activity with severity of aortic stenosis in vivo has not been fully elucidated yet. Pericoronary adipose tissue imaging with coronary computed tomography angiography has been shown to reflect the degree of inflammation associated with atherosclerotic plaque instability. We hypothesized that this imaging may be applicable to measure inflammatory activity at aortic valve and then stratify severity of aortic stenosis. Purpose To elucidate the association of CT-derived periaortic valve adipose tissue (PAVAT) with severity of AS. Methods The INTERACT study is the multi-center retrospective study which enrolled 219 patients receiving MSCT imaging due to coronary artery stenosis and/or AS. Computed tomography angiography which was performed by the second and third-generation dual-source CT scanners. Then, periaortic valve adipose tissue attenuation at sinotubular junction was measured by commercially available software (Figure). Clinical demographics and CT-derived measures were compared in patients with no/mild AS (n=81), moderate (n=32) and severe AS (n=106). Results Patients with severe AS were more likely to be older (p<0.01), female (p<0.01), accompanied by a lower BMI (p<0.01). CT imaging analysis demonstrated that severe AS was associated with a higher PAVAT (p<0.001). On multivariate analysis adjusting clinical characteristics, in addition to female (OR=8.26, 95%CI=2.28 – 29.92, p=0.001) and calcium score (OR=1.25, 95%CI=1.16 – 1.35, p<0.001), PAVAT attenuation was an independent factor associated with severe AS (OR=1.20, 95%CI=1.08 – 1.32, p<0.001). Receiver operating characteristic curve analysis demonstrated PAVAT attenuation >-63.0 HU (AUC=0.84, sensitivity=77.4%, specificity=79.7%) and calcium score >1207 as optimal cut-off values to predict severe AS. Of note, the increasing number of independent features (female, PAVAT>-63.0 HU, calcium score>1207) was associated with a greater frequency of severe AS (p<0.001). In particular, the frequency of severe AS rose to 90.7% in patients with all of these three features (Figure). Conclusion The degree of PAVAT attenuation was associated with severity of AS. Given that higher PAVAT represented a feature of severe AS, our findings support inflammation activity as an important driver associated with the formation and progression of AS.Table 1, Figure 1 Figure 2, 3