Key Points:
- The SMART trial is the first randomized non-inferiority trial to test a head-to-head comparison between the Medtronic Evolut valve (Evolut PRO/PRO+/FX) and Edwards SAPIEN valve (SAPIEN 3/3 Ultra) in patients with severe aortic stenosis and small aortic annuli.
- In the SMART trial, there was no significant difference in the primary composite outcome of mortality, disabling stroke or heart failure hospitalization at 12 months between patients who received the Evolut valve and those who received the SAPIEN valve.
- Patients who received the Evolut valve had a lower incidence of bioprosthetic valve dysfunction and improved hemodynamics including a larger effective orifice area and lower mean gradient compared to those who received the SAPIEN.
The Small Annuli Randomized to Evolut or SAPIEN (SMART) trial is the first prospective, randomized control trial to compare the balloon-expandable SAPIEN valve and self-expanding Evolut valves in patients with severe aortic stenosis and small aortic annuli.
Patients with symptomatic severe aortic stenosis and an aortic-valve annulus area of 430 mm2 or less were randomized in a 1:1 ratio to undergo TAVR with either a self-expanding supraannular valve or a balloon-expandable valve. The coprimary end points, each assessed through 12 months, were a composite of death, disabling stroke, or rehospitalization for heart failure (tested for noninferiority) and a composite end point measuring bioprosthetic-valve dysfunction (tested for superiority).
The SMART trial enrolled 716 patients with a low to intermediate risk of cardiac events across 83 different international sites in 13 countries. At one year, there was no statistically significant difference in the first primary composite endpoint between patients who received the Evolut valve and those who received the SAPIEN. The incidence of death, disabling stroke or hospitalization for heart failure was 9.4% in patients who received the Evolut valve and 10.6% in those who received the SAPIEN valve (difference, −1.2 percentage points; 90% confidence interval [CI], −4.9 to 2.5; P<0.001 for noninferiority). Furthermore, there was a significantly lower incidence of the second primary endpoint, bioprosthetic valve dysfunction at 12 months, in the Evolut arm (9.4% compared to 41.6%; difference, −32.2 percentage points; 95% CI, −38.7 to −25.6; P<0.001 for superiority). The Evolut valve also performed better in the predetermined secondary outcomes and had an 8 mmHg lower mean gradient, 0.5 cm2 greater effective orifice area and 6.8% lower incidence of severe pulmonary regurgitation. Patients who received the Evolut valve had lower rates of aortic regurgitation and a better performance on quality of life metrics.
As the study’s lead author, Howard C. Hermann, section chief for interventional cardiology at the University of Pennsylvania, notes, “We think it’s important to study this population, which represents up to 40% of all patients getting TAVR, and it’s important to study women, who make up the majority of the small annulus population.” The author argues that the self-expanding design of the Evolut allows for implantation of a valve with a larger opening, which contributes to the hemodynamic benefits seen with Evolut implantation compared to the SAPIEN valve.
In conclusion,. among patients with severe aortic stenosis and a small aortic annulus who underwent TAVR, a self-expanding supraannular valve was noninferior to a balloon-expandable valve with respect to clinical outcomes and was superior with respect to bioprosthetic- valve dysfunction through 12 months. The SMART trial is the largest to randomize patients to the 2 most widely used TAVR devices and the largest TAVR trial to enroll mostly women. Future studies will continue to follow this population for up to five years to provide an assessment of long-term outcomes in this population.