Quantified degree of eccentricity of aortic valve calcification predicts risk of paravalvular regurgitation and response to balloon post-dilation after self-expandable transcatheter aortic valve replacement

Abstract

Objectives: We sought to investigate the prognostic value of aortic valve calcification (AVC) eccentricity in predicting the risk of paravalvular regurgitation (PVR) and the response to balloon post-dilation (BPD) in patients undergoing transcatheter aortic valve replacement (TAVR). Background: Limited data exist regarding the impact of AVC eccentricity on the risk of significant PVR and the response to BPD. Methods: We analyzed 85 patients with severe aortic stenosis who underwent self-expandable TAVR. AVC was quantified as the total amount of calcification (total AVC load) and as the eccentricity of calcification (AVC eccentricity index) using calcium volume scoring with contrast computed tomography angiography (CTA). The AVC eccentricity index was defined as the maximum absolute difference in calcium volume scores between 2 adjacent sectors, which was not confined to leaflet sectors. The perimeter undersizing index was calculated to take the relative size of the device to the annulus into account. PVR was defined as present when blood flowed abnormally through a channel between the device and annulus as a result of incomplete sealing. The primary study endpoint was the occurrence of significant PVR, defined as ≥moderate PVR. The secondary endpoint was the response to BPD, a widely adopted strategy to reduce the degree of PVR in cases of frame under-expansion. Results: Total load of and eccentricity index of AVC were significant predictors for the occurrence of ≥moderate PVR and AVC eccentricity index had a better predictive value than total AVC load (area under the curve = 0.863 versus 0.760, p for difference = 0.006). In multivariate analysis, AVC eccentricity index was an independent predictor for the risk of ≥moderate PVR regardless of perimeter undersizing index. There was no incidence of ≥moderate PVR in patients with extensive (total AVC load of >1099.1 mm3) but symmetric calcification (AVC eccentricity index of ≤272.8 mm3). The AVC eccentricity index was the only significant parameter to predict the poor response to BPD (area under the curve = 0.775, p = 0.004). The addition of AVC eccentricity index to perimeter undersizing index significantly increased the discriminative ability of the prediction model and improved the classification of the risk estimation, whereas total AVC amount did not. Conclusions: Pre-procedural assessment of AVC eccentricity using CTA provides useful predictive information on the risk of significant PVR and the response to BPD in patients undergoing TAVR with self-expandable valves.