Anatomic influencing factors on implantation depth of self-expandable valve and its short-term clinical outcome: a retrospective cohort study of 54 cases

Objective To investigate the anatomic factors influencing the implantation depth (ID) of self-expandable valve during transcatheter aortic valve replacement (TAVR) surgery, and to analyze the impact of ID on the short-term clinical prognosis. Methods Clinical data of 54 patients with severe aortic stenosis who underwent TAVR in our hospital from October 2017 to May 2020 were collected and retrospectively analyzed. The anatomic diameter of aortic root and its ratio to the implanted valve size was measured and calculated, and the depth of the valve implanted was also measured. The patients were assigned into either over-implanted group (>14.8 mm, the highest quartile of ID) or well-implanted group (≤14.8 mm) based on the ID of their valve. The differentiation of anatomical structures was compared between the 2 groups. Additionally, the impacts of ID on the clinical outcomes such as hemodynamics and conduction block were analyzed. Results There were 21 cases of bicuspid aortic valve (BAV) and 33 cases of tricuspid aortic valve (TAV), and the ID of valve was 0~21 mm, with a median of 11.6 mm. Among the BAV patients, the average diameter of sinotubular junction (STJ) was significantly larger in the over-implanted group than the well-implanted group (36.06±2.29 vs 29.69±2.55 mm, P=0.001). As for the TAV patients, the over-implanted group had a higher proportion of large prosthesis implantation (100.0% vs 26.9%, P=0.025), and a smaller ratio of the length of the left ventricular output tract to the bottom diameter of the valve (0.99±0.03 vs 1.12±0.15, P=0.021) when compared with the well-implanted group. Postoperative mortality was comparable between the 2 groups (4.88% vs 15.38%, P=0.242). However, the incidence of being converted to open surgery was higher in the over-implanted group than the other group (15.4% vs 0%, P=0.055). In 1 week after TAVR, there were no statistical differences in the mean aortic valve gradient, maximum velocity, permanent pacemaker implantation rate, moderate or severe paravalvular leakage, or new-onset left bundle branch block (LBBB) between the 2 groups (P>0.05), whereas the incidence of new-onset LBBB (50.0% vs 13.3%, P=0.044) and paravalvular leakage (33.3% vs 0%, P=0.009) were higher in the over-implanted group on the 30th day. The early safety was inferior in the over-implanted group (69.2% vs 95.1%, P=0.025). Conclusion The anatomical structure of the aortic root and its ratio to the size of the implanted valve have a certain effect on the implantation depth of self-expandable prosthesis. The BAVs patients with greater STJ as well as those TAVs patients treated with larger size valve may be both correlated with increased risks of deep implantation. Over implantation of the valve may increase the risk of new-onset LBBB and moderate or severe paravalvular leakage in 1 month after operation, and thus compromise the early safety.