Randomized Trial Finds Self-Expanding TAVR Outperforms Balloon-Expandable Device in Patients with Small Aortic Annuli

Core Concepts

A randomized trial demonstrated that a self-expanding TAVR device performed better than a balloon-expandable device on multiple prognostic measures of valve function at 1 year in patients with severe aortic stenosis and small aortic annuli.

Abstract

The SMART trial was a randomized, multinational study that compared the performance of a self-expanding TAVR device (Evolut, Medtronic) to a balloon-expandable device (Sapien, Edwards Lifesciences) in 716 patients with severe aortic stenosis and small aortic annuli (< 430 mm2).
Key findings:

The self-expanding device was non-inferior to the balloon-expandable device on the primary composite endpoint of mortality, disabling stroke, and heart failure hospitalization at 1 year.
The self-expanding device was superior to the balloon-expandable device on the primary composite hemodynamic endpoint, driven by lower rates of hemodynamic structural valve dysfunction (3.2% vs 32.2%) and non-structural valve dysfunction (5.9% vs 18.2%).
Secondary endpoints, including moderate-to-severe prosthesis-patient mismatch (10.3% vs 35.1%) and mean gradient (7.7 vs 15.7 mmHg), also favored the self-expanding device.
Bioprosthetic valve dysfunction, assessed only in female participants, was lower with the self-expanding device (8.4% vs 41.8%).
The self-expanding device had a higher rate of device success at 30 days but also longer procedure times and greater contrast volume use.
Safety outcomes were similar between the two groups.
The investigators expect the hemodynamic advantages of the self-expanding device to translate into better long-term outcomes, though the high median age of 80 years introduces competing mortality risks that may dilute differences over time.

Stats

Aortic valve annulus area < 430 mm2
Mortality, disabling stroke, and heart failure hospitalization at 1 year: 9.4% vs 10.6% (self-expanding vs balloon-expandable)
Hemodynamic structural valve dysfunction: 3.2% vs 32.2% (self-expanding vs balloon-expandable)
Non-structural valve dysfunction: 5.9% vs 18.2% (self-expanding vs balloon-expandable)
Moderate-to-severe prosthesis-patient mismatch: 10.3% vs 35.1% (self-expanding vs balloon-expandable)
Mean gradient: 7.7 vs 15.7 mmHg (self-expanding vs balloon-expandable)
Bioprosthetic valve dysfunction in females: 8.4% vs 41.8% (self-expanding vs balloon-expandable)
Device success at 30 days: 85.2% vs 59.2% (self-expanding vs balloon-expandable)
Procedure time: 116 vs 106 minutes (self-expanding vs balloon-expandable)
Contrast volume: 121 vs 95 mL (self-expanding vs balloon-expandable)
Pacemaker implantation: 14.0% vs 9.3% (self-expanding vs balloon-expandable)

Quotes

"we expect to see better outcomes for those who received the self-expanding device in about 3-4 years"
"It is important to looked specifically at this group because women present differently than men and are at greater risk of complications after surgery or TAVR"
"This study is really going to provide us with a rich data with which we can really explore and confirm the benefit of TAVR in our female patients"

Key Insights Distilled From

For Small Annuli, Self-Expanding TAVR May Have an Advantage

by Ted Bosworth at www.medscape.com 04-11-2024

https://www.medscape.com/viewarticle/small-annuli-self-expanding-tavr-may-have-advantage-2024a10006wi

Deeper Inquiries

What are the potential mechanisms underlying the superior hemodynamic performance of the self-expanding TAVR device compared to the balloon-expandable device in patients with small aortic annuli?

The superior hemodynamic performance of the self-expanding TAVR device in patients with small aortic annuli can be attributed to several potential mechanisms. Firstly, the supra-annular design of the self-expanding device, such as the Evolut, allows for better valve positioning and sealing, leading to improved hemodynamics. This design feature minimizes paravalvular leaks and enhances overall valve function. Additionally, the self-expanding device's ability to conform to the irregularities of the aortic annulus more effectively than the balloon-expandable device may contribute to its superior hemodynamic performance. The self-expanding device's radial force and anchoring mechanisms also play a role in ensuring optimal valve function and reducing gradients, further enhancing hemodynamic outcomes.

How might the long-term durability and clinical outcomes differ between the two TAVR devices, given the competing mortality risks in this elderly patient population?

In the context of elderly patients with severe aortic stenosis and small aortic annuli, the long-term durability and clinical outcomes of the self-expanding and balloon-expandable TAVR devices may vary. The self-expanding device's superior hemodynamic performance, as evidenced in the trial, suggests that it may lead to better long-term durability by reducing the risk of bioprosthetic valve dysfunction and structural valve deterioration. This could translate into improved clinical outcomes, such as lower rates of rehospitalization, valve reintervention, and heart failure exacerbations over time. However, the competing mortality risks in this elderly population, with a median age of 80 years, may impact the detection of differences in long-term outcomes between the two devices. The potential benefits of the self-expanding device in terms of hemodynamics and valve function may need to be balanced against the overall life expectancy and comorbidities of the patients to determine the most appropriate device selection for optimal clinical outcomes.

What other patient or procedural factors may influence the comparative performance of self-expanding and balloon-expandable TAVR devices, and how can this information guide device selection for individual patients?

Several patient and procedural factors can influence the comparative performance of self-expanding and balloon-expandable TAVR devices in individual patients. Patient-specific factors, such as aortic annulus size, anatomy, degree of calcification, and presence of comorbidities like hypertension and heart failure, can impact device selection. The size and shape of the aortic annulus, particularly in cases of small annuli, may favor the use of a self-expanding device for better sealing and positioning. Procedural considerations, including the ease of deployment, need for post-dilation, and risk of complications like paravalvular leaks, also play a role in device selection.
Guiding device selection for individual patients involves a comprehensive assessment of these factors to determine the most suitable TAVR device. The trial results indicating the superiority of the self-expanding device in patients with small annuli and the potential long-term benefits in hemodynamics and valve function can inform decision-making. However, a personalized approach that considers each patient's unique characteristics, preferences, and expected outcomes is essential in selecting the optimal TAVR device for maximizing clinical success and durability.