Small aortic annulus is recognized as a critical risk factor in transcatheter aortic valve replacement, predisposing patients to prosthesis-patient mismatch. This case series examines 3 distinct anatomical subtypes of small aortic annulus patients undergoing transcatheter aortic valve replacement: 1) tricuspid aortic valve morphology; 2) type 0 bicuspid aortic valve; and 3) failed surgical bioprosthesis. The analysis highlights subtype-specific technical challenges and procedural optimization strategies, emphasizing the importance of preprocedural imaging and prosthesis selection in mitigating complications.