Impact of Small Aortic Annuli on the Performance of Transcatheter Aortic Valve Replacement Bioprostheses: An Updated Meta-analysis of Recent Studies.

A metanalysis of available randomized controlled trials and observational studies comparing self-expanding and balloon-expandable bioprostheses in patients with small aortic annulus and aortic stenosis for short and midterm hemodynamic and clinical outcomes was performed. 21 studies with a total 8647 patients (self-expanding, n=4,336 patients vs balloon-expandable, n= 4,311 patients) were included. Self-expanding bioprostheses had a lower post-operative mean gradient at 30 days (MD -5.16, 95%CI 4.7-5.5, p value <0.001) and at one year (MD -6.6, 95%CI 6.1-7.03, p value <0.001), with a larger indexed Effective Orifice Area (0.17, 95%CI 0.13-0.22, p value <0.001and 0.17, 95%CI 0.08-0.27, p value < 0.001) at both time intervals. Balloon-expandable bioprostheses had a higher risk of 30-day and 1-year severe prosthesis-patient mismatch (RR 1.07, 95%CI 1.04-1.09, p value < 0.001; RR 1.07, 95%CI 1.04-1.11, p value <0.001). 30-day and 1 year paravalvular leaks (RR 0.99, 95%CI 0.98-0.99, p value < 0.001; RR 0.89, 95%CI 0.82-0.95, p value <0.001) and permanent pacemaker implantation (RR 0.97, 95%CI .94-0.99, p value 0.01, I2= 40%,) were lower in balloon-expandable group. Balloon-expandable bioprostheses were associated with lower risk of in-hospital stroke (RR 0.99, 95%CI 0.98-1,p value= 0.01). In conclusion, in patients with small aortic annulus and aortic stenosis, SE bioprostheses have superior haemodynamic performance but higher rates of PVL, PPI and in-hospital stroke. BE bioprostheses were associated with a higher risk of severe PPM.