When to Refer for SAVR in an Era of Expanding TAVR Use?

As transcatheter aortic valve replacement (TAVR) expands in use as an alternative to surgical AVR (SAVR) for patients with severe symptomatic aortic valve stenosis across a wide spectrum of surgical risk, which patients are still best served by SAVR?

That question is at the center of a comprehensive State of the Art Review recently published in the European Heart Journal by an international team of expert cardiologists and cardiothoracic surgeons.

Their bottom-line guidance is that the many intersecting factors that influence the choice of TAVR versus SAVR preclude any single uniform treatment strategy but instead underscore the importance of decision-making by a multidisciplinary heart team that accounts for the individual patient’s clinical and anatomic factors and lifetime management considerations.

The review lays out the latest evidence across a range of factors relevant to the decision while also proposing several potential lifetime management strategies for patients.

“We devoted particular attention to patient populations that were not included in randomized clinical trials of TAVR,” observes interventional cardiologist Samir Kapadia, MD, a co-author of the review and Chair of Cardiovascular Medicine at Cleveland Clinic.

Gaps in TAVR’s current evidence base

Across multiple randomized trials in patients at various levels of surgical risk, TAVR has repeatedly been shown to yield mortality and stroke outcomes comparable to or better than those with SAVR through the mid-term follow-up that is currently available. This outcomes profile, together with TAVR’s reduced invasiveness and shorter recovery time, has elevated transfemoral TAVR to a spot alongside SAVR in having a class I recommendation for patients with severe symptomatic aortic stenosis in the latest U.S. and European treatment guidelines.

At the same time, the evidence supporting TAVR was limited to carefully chosen patient populations, and uncertainties remain around the long-term durability of TAVR (as well as SAVR) prostheses and what constitutes ideal lifetime management for patients with severe aortic stenosis.

Anatomic and clinical risk stratification

Many of the knowledge gaps around TAVR’s utility involve anatomic or clinical features not accounted for in initial clinical trials. Much of the review discusses these features in the context of anatomic risk stratification.

“When the aortic valve anatomy is favorable for TAVR and transfemoral access is possible, TAVR will result in clinical outcomes comparable to those of SAVR,” Dr. Kapadia explains. “In contrast, when patients have unfavorable anatomy in the TAVR implantation zone or poor femoral access, SAVR is the treatment of choice. But there is also a ‘gray zone’ of intermediate-risk situations that demand judicious, individualized decision-making, and that’s what we aimed to address.”

The review covers the following anatomic/clinical factors that generally favor SAVR, with detailed discussion of when and why SAVR may be indicated:

• Severely calcified aortic valve or left ventricular outflow tract
• Elevated risk of new-onset conduction disturbances
• Extreme annulus dimensions, either large or small
• Noncalcified aortic valve morphology
• Low take-off of coronary ostia combined with shallow sinus of Valsalva
• Horizontal aorta
• Poor femoral or peripheral access
• Certain cases of failed surgical bioprostheses, especially in the presence of significant paravalvular regurgitation

Additional discussion is devoted to the following, with these general recommendations:

• Bicuspid aortic stenosis. TAVR with contemporary prostheses appears to be equivalent to SAVR for elderly patients with bicuspid aortic valves, but SAVR is preferred in young patients and when the bicuspid valve morphology is unfavorable for TAVR or marked by significant aortopathy.
• Mixed valve disease is best managed at a comprehensive valve center. Preferred treatment of aortic stenosis accompanied by either aortic regurgitation, primary mitral regurgitation or tricuspid regurgitation depends on the severity of the regurgitant disease, with SAVR favored for severe forms and TAVR for mild forms. Mixed valve disease involving moderate forms of regurgitant disease, severe secondary mitral regurgitation or moderate to severe mitral stenosis falls in a gray zone where procedural choice should be highly individualized.
• Coexistent coronary artery disease (CAD). In this setting, the choice of AVR approach should be guided by the patient’s surgical risk and CAD severity, among other factors. Low surgical risk and complex CAD (e.g., three-vessel disease and a SYNTAX score > 22, or left main disease and a SYNTAX score > 32) favor a surgical approach of SAVR plus coronary artery bypass grafting. High surgical risk and milder CAD (e.g., one-/two-vessel disease, or left main disease and a SYNTAX score ≤ 22) favor an interventional approach of TAVR plus percutaneous coronary intervention.

The figure below summarizes the contributions of many of these clinical and anatomic factors to decision-making between TAVR and SAVR.

Figure. Graphical abstract of the decision-making process when choosing between TAVR (TAVI) and SAVR. Reprinted with permission from Windecker et al., European Heart Journal (25 Apr 2022), doi.org/10.1093/eurheartj/ehac105. © The Authors 2022. Published by Oxford University Press on behalf of European Society of Cardiology.

A look at lifetime management strategies

The review concludes with a detailed discussion of lifetime management, noting that this issue looms larger as TAVR use expands to younger and lower-risk patients with longer life expectancy. Direct evidence on this issue is limited, as comparative data between TAVR and SAVR are currently restricted to five to eight years.

Valve durability is central to lifetime management, and durability data for transcatheter valves are chiefly derived from patients treated at an advanced age — i.e., a mean of over 80 years. At the same time, data on the long-term durability of surgical bioprostheses are limited as well, prompting the authors to state that valve durability remains inconclusive in the decision-making context.

Other questions related to lifetime management that require continued longitudinal monitoring include the clinical relevance of:

• Mild paravalvular regurgitation, which remains more common after TAVR than SAVR
• New conduction disturbances, which occur more often following TAVR versus SAVR
• New-onset atrial fibrillation, which occurs more frequently after SAVR than TAVR

Additionally, the need for lifelong anticoagulation in patients undergoing SAVR with a mechanical prosthesis is a key consideration, particularly for younger individuals. Noting that younger patients who undergo treatment with bioprostheses may require three or more interventions over their lifetime, the authors outline the pros and cons of various sequential intervention strategies for various patient types, such as TAVR-SAVR-TAVR or SAVR-TAVR-TAVR, depending on patients’ individual circumstances and values.

The heart team is pivotal

“The many considerations that factor into the initial decision between TAVR and SAVR — not to mention the need to plan for potential subsequent valve procedures down the road — explain the need for decision-making by a multidisciplinary heart team at a valve center of excellence to ensure the highest-level, most fully informed care for aortic stenosis,” says Dr. Kapadia. “At this point, this is one of the few certainties in decision-making around TAVR versus SAVR. Another certainty is that both SAVR and TAVR technologies and techniques will continue to improve, and that will further refine decision-making in the years ahead.”

A surgeon’s perspective

“SAVR can be preferred when patient anatomy is suboptimal for TAVR,” says James Yun, MD, PhD, a Cleveland Clinic cardiothoracic surgeon who performs both procedures but wasn’t involved in the European Heart Journal review. He says leading examples include severe calcification of the left ventricular outflow tract, bulky eccentric leaflet calcification, excessive annular size and low-lying coronary ostia with small sinuses of Valsalva.

“Surgery also is preferred when low- and intermediate-risk patients present with a coincident second surgical indication, such as ascending aortic aneurysm, coronary artery disease or other valvular disease,” adds Dr. Yun. “Finally, in the lifetime management of aortic stenosis, SAVR is seriously considered in patients’ younger years to match procedural risk and advancing age appropriately.”