Abstract Body (Do not enter title and authors here): Introduction: Both self-expanding (SEV) and balloon-expandable (BEV) valves are used in transcatheter aortic valve implantation (TAVI) for patients with severe aortic stenosis (AS) and small aortic annulus (SAA). This updated meta-analysis compares the efficacy and safety of SEV versus BEV in TAVI for these patients.

Hypothesis: This study investigates whether SEV valves are hemodynamically and clinically superior to BEV valves in patients with small aortic annulus.

Methods: PubMed, SCOPUS, and Cochrane Central databases were systematically searched for randomized and observational studies comparing SEV and BEV in TAVI for SAA patients. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random-effects model for clinical outcomes (all-cause mortality, stroke, permanent pacemaker implantation [PPI]) and hemodynamic parameters (mean gradient [MG], indexed effective orifice area [iEOA], moderate to severe prosthesis-patient mismatch [PPM], and paravalvular leak [PVL]).

Results: A total of 21 studies involving 6,515 patients (58.4% treated with SEV) were included. SEV valves were associated with lower all-cause mortality (OR 0.75; 95% CI 0.60-0.95; p=0.014), lower MG (OR -4.44; 95% CI -5.48-3.39; p<0.01), higher iEOA (OR 0.23; 95% CI 0.13-0.23; p<0.01), and less moderate to severe PPM (OR 0.31; 95% CI 0.22-0.45; p<0.001). However, SEV valves had higher rates of PPI (OR 1.35; 95% CI 1.01-1.80; p=0.042) and PVL (OR 2.69; 95% CI 1.58-4.57; p<0.001). Stroke rates were not significantly different between the groups.

Conclusion: In patients with severe AS and SAA, TAVI with SEV valves showed better outcomes in all-cause mortality, MG, iEOA, and moderate to severe PPM. However, BEV valves had advantages in lower PPI and PVL rates. These findings should be interpreted cautiously due to the predominance of observational studies and varying valve types and generations used.