ObjectiveTo analyze the differences in clinical outcomes between sutureless aortic valve replacement (SUAVR) and conventional aortic root enlargement (ARE) techniques in patients with small aortic annulus (SAA). MethodsSAA patients undergoing aortic valve replacement at Beijing Anzhen Hospital, Capital Medical University from April 2018 to January 2025 were retrospectively enrolled. Patients were divided into a SUAVR group and an ARE group (including Nicks technique and Manouguian technique) according to surgical approaches. The primary endpoints were postoperative maximum transvalvular pressure gradient and indexed effective orifice area (iEOA). After adjusting for confounding factors using analysis of covariance, the differences in iEOA among the three surgical procedures were compared. ResultsA total of 56 SAA patients were included, with 26 patients in the SUAVR group and 30 patients in the ARE group (19 patients using Nicks technique and 11 patients using Manouguian technique). The median age of SUAVR group was significantly higher than that of ARE group (62.5 years vs. 57.5 years, P=0.035). Female proportions were 84.6% and 83.3%, respectively. In the ARE group, 73.3% of the patients received mechanical valve implantation and 1 patient died during the perioperative period. Postoperative transvalvular pressure gradient was lower in the SUAVR group compared to that in the ARE group [11.5 (8.3, 23.5) mm Hg vs. 19.0 (16.0, 26.0) mm Hg, P=0.005]. Significant differences existed in iEOA among the three techniques (P<0.001): Nicks group (1.10±0.14) cm2/m2, Manouguian group (1.27±0.16) cm2/m2, with SUAVR group showing the highest value (1.69±0.18) cm2/m2. After adjusting for confounding factors, SUAVR still demonstrated significantly higher adjusted iEOA than both Nicks and Manouguian groups (P<0.001). One patient in the ARE group developed moderate prosthesis-patient mismatch. No permanent pacemaker implantation occurred. ConclusionAmong this cohort of SAA patients, those receiving conventional ARE are younger with higher rates of mechanical valve implantation. SUAVR demonstrates favorable perioperative safety while achieving comparable hemodynamic performance to conventional ARE techniques, with significant advantages in iEOA. SUAVR can serve as an effective complementary strategy to traditional ARE techniques in selected SAA patients.