Severe aortic stenosis with low aortic valve calcification: characteristics and outcome following transcatheter aortic valve implantation

High aortic valve calcification (AVC) assessed with CT may be used to differentiate between severe and non-severe aortic stenosis (AS). Nonetheless, in some cases patients with low calcification are diagnosed with haemodynamically severe AS. The prevalence, mechanism of valve stenosis and implications for transcatheter aortic valve implantation (TAVI) of low AVC severe AS remain unclear. We assessed the clinical and haemodynamic characteristics and the outcome of patients with severe AS and low AVC that undergo TAVI.

Ninety-three patients that had low CT aortic valve calcification score (AVCS) were compared to 470 patients with high AVCS. High gradient severe AS was found among 53.8% (50/93) of the patients with low AVCS vs. 86% (404/470) of the patients with high AVCS (P < 0.001). Device success rate was similar between both groups. There were significantly lower rates of postprocedural paravalvular regurgitation (PVR) in the low AVCS group (≥ mild PVR: 12.9% vs. 23.6%; P = 0.03). Overall, there were only two cases (0.4%) of valve embolization in patients with high AVCS and 1 (1.1%) in patients with low AVCS (P = 0.42). Thirty-day mortality and major complications were similar between groups.

Balloon-expandable TAVI in patients with a mildly calcified aortic valve was not associated with increased risk of valve embolization or mortality. We demonstrated high device success and lower rates of PVR for these patients. These findings suggest that in patients with evidence of haemodynamically severe AS at echocardiography, the presence of low ACVS at CT should not preclude the consideration of TAVI.