Based on several prospective randomized trials comparing transcatheter aortic valve replacement (TAVR) with surgery, TAVR appears to be the predominant treatment modality for most patients with symptomatic severe aortic stenosis. Studies of TAVR have shown that self-expanding supra-annular valves (SEV) have better hemodynamic properties than balloon-expandable valves (BEV). The hemodynamic differences between these two valve platforms may be particularly important in patients with a narrow aortic annulus. Patients with a small aortic annulus are at higher risk for impaired valve hemodynamics after the procedure, including high gradient, prosthesis-patient mismatch, reduced exercise capacity, and impaired prosthesis durability.

The SMART study evaluated 1-year clinical outcomes and valve performance in patients with symptomatic advanced aortic stenosis and a small aortic annulus between SEV and BEV. Methods: This was a prospective, randomized, controlled trial. Patients with severe aortic stenosis, an aortic annulus area of 430 mm2 or less as measured by computed tomography, and eligible for transfemoral TAVR were included. The SEV was the Evolut PRO/PRO+/FX (Medtronic) and the BEV was the SAPIEN 3/3 Ultra (Edwards Lifesciences). The primary composite endpoint of the study was death, stroke with sequelae, and rehospitalization for heart failure at one year, with non-inferiority between the two valve groups being tested as the primary composite endpoint. The secondary composite endpoint was bioprosthetic valve dysfunction, and superiority between the two valve groups was tested

This was a prospective, randomized, controlled trial. Patients with severe aortic stenosis, an aortic annulus area of 430 mm2 or less as measured by computed tomography, and eligible for transfemoral TAVR were included. The SEV was the Evolut PRO/PRO+/FX (Medtronic) and the BEV was the SAPIEN 3/3 Ultra (Edwards Lifesciences). The primary composite endpoint of the study was death, stroke with sequelae, and rehospitalization for heart failure at one year, with non-inferiority between the two valve groups being tested as the primary composite endpoint. The secondary composite endpoint was bioprosthetic valve dysfunction, and superiority between the two valve groups was tested.

A total of 716 patients from 83 centers and 13 countries were enrolled. The mean age of the patients was 80 years, and approximately 87% were female. The primary composite endpoints were 9.4% events in the SEV group and 10.6% events in the BEV group at 12 months. The secondary composite endpoint of bioprosthetic valve dysfunction was reported as 9.4% in the SEV group and 41.6% in the BEV group. The mean aortic valve gradient was statistically lower, the mean effective orifice area was higher, the percentage of women with hemodynamic structural valve dysfunction was lower, and the percentage of women with bioprosthetic valve dysfunction was lower in the SEV group than in the BEV group.

ThIn patients with severe aortic stenosis and a small aortic annulus undergoing TAVR, SEV was superior in terms of bioprosthetic valve function and non-inferior in terms of clinical outcomes at 1-year follow-up.

In patients with small aortic annulus, the use of SEV may be preferable in terms of hemodynamic parameters, although there is no difference in clinical outcomes. Now that TAVR has become a preferable treatment modality in low- and intermediate-risk patient groups with relatively higher life expectancy, hemodynamic parameters are of great importance in terms of durability. Since this is a short-term follow-up study, it is necessary to see the results of a 5-year long-term follow-up in terms of clinical outcomes.