Comparative Effectiveness of Balloon-Expandable and Self-Expanding Valves in Small Aortic Annulus Transcatheter Aortic Valve Replacement: An Updated Meta-Analysis of Randomized and Propensity Score Matched Studies.

Patients with small aortic annuli (SAA) undergoing transcatheter aortic valve replacement (TAVR) are at increased risk of elevated transvalvular gradients and prosthesis-patient mismatch (PPM), making valve selection critical. We hypothesized that balloon-expandable valves (BEVs) and self-expandable valves (SEVs) differ in their clinical and hemodynamic outcomes in this population. We searched PubMed, Cochrane, ScienceDirect, and Google Scholar for studies published before May 2025. Randomized controlled trials (RCTs) and propensity score matched (PSM) studies comparing BEVs and SEVs were included. Outcomes were pooled using mean differences (MD) or risk ratios (RR) with 95% confidence intervals (CIs). Analyses were performed in R (v4.4.2), and heterogeneity was assessed using the I² statistic. Fourteen studies, 2 RCTs, and 12 PSM studies met the inclusion criteria. Compared to SEVs, BEVs were associated with a significantly lower indexed effective orifice area (MD -0.18; 95% CI -0.24 to -0.11; p <0.01), higher mean transvalvular gradient (MD 4.27; 95% CI 3.07-5.47; p <0.01), and increased risk of PPM (RR 1.56; 95% CI 1.14-2.13; p = 0.006) and severe PPM (RR 2.66; 95% CI 1.97-3.60; p <0.001). BEVs were linked to lower rates of pacemaker implantation (RR 0.64; 95% CI 0.46-0.89; p = 0.008) and major bleeding (RR 0.69; 95% CI 0.50-0.96; p = 0.028). In SAA patients undergoing TAVR, BEVs show inferior hemodynamics but reduced need for pacemakers and bleeding risk. In conclusion, long-term prospective studies with contemporary devices are needed to clarify these trade-offs.