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 (SE) and balloon-expandable (BE) bioprostheses in patients with small aortic annulus and aortic stenosis for short- and midterm hemodynamic and clinical outcomes was performed. A total of 21 studies with a total 8,647 patients (SE: n = 4,336 patients vs BE: n = 4,311 patients) were included. SE bioprostheses had a lower postoperative mean gradient at 30 days (Mean Difference [MD] −5.16, 95% confidence interval [CI] 4.7 to 5.5, p <0.001) and at 1 year (MD −6.6, 95%CI 6.1 to 7.03, p <0.001), with a larger indexed effective orifice area (0.17, 95% CI 0.13 to 0.22, p <0.001 and 0.17, 95% CI 0.08 to 0.27, p <0.001) at both time intervals. BE bioprostheses had a higher risk of 30-day and 1-year severe prosthesis-patient mismatch (risk ratio [RR] 1.07, 95% CI 1.04 to 1.09, p <0.001; RR 1.07, 95% CI 1.04 to 1.11, p <0.001). The 30-day and 1 year paravalvular leaks (RR 0.99, 95% CI 0.98 to 0.99, p <0.001; RR 0.89, 95% CI 0.82 to 0.95, p <0.001) and permanent pacemaker implantation (RR 0.97, 95% CI 0.94 to 0.99, p 0.01, I2 = 40%,) were lower in the BE group. BE bioprostheses were associated with a lower risk of in-hospital stroke (RR 0.99, 95% CI 0.98 to 1, p = 0.01). In conclusion, in patients with small aortic annulus and aortic stenosis, SE bioprostheses have superior hemodynamic performance but higher rates of paravalvular leak, permanent pacemaker implantation, and in-hospital stroke. BE bioprostheses were associated with a higher risk of severe prosthesis-patient mismatch.