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Low-Risk SAVR in Patients Not Included in Randomized TAVR-SAVR Trials
Quick Takes
- In a real-world cohort of consecutive low-risk severe aortic stenosis patients, over 40% fell into at least one subgroup that would have excluded them from enrollment in a low-risk TAVR versus SAVR trial.
- The nontricuspid aortic valve subgroup accounted for the majority of cases (27.6%), followed by concomitant ascending aorta replacement (10.5%), severe CAD, and concomitant mitral/tricuspid valve (MV/TV) disease (both 5.8%).
- The nontricuspid aortic valve group had a 30-day mortality of only 0.9%, lower than would have been predicted by STS scores and trileaflet-matched counterparts (OR, 0.42; 95% CI, 0.22-0.81).
- Concomitant ascending aorta repair and severe CAD groups also had low 30-day and 1-year mortality, while the concomitant MV/TV group was the only subgroup in which mortality exceeded rates predicted by STS scores.
Study Questions:
Recent clinical trials have shown noninferior or even superior outcomes for transcatheter aortic valve replacement (TAVR) versus surgical aortic valve replacement (SAVR) in low-risk patients with severe aortic stenosis (SAS), but certain subgroups (e.g., patients with nontricuspid aortic valves [NTAVs]) have been excluded. In a real-world clinical setting, what percentage of low-surgical risk SAVR patients fall into each of these subgroups and how do their surgical outcomes compare to other SAVR patients?
Methods:
All patients with SAS and low-surgical risk (defined as a Society of Thoracic Surgeons [STS] score <4%) who underwent SAVR at a single-center from 2000-2019 were included. Cases of acute infective endocarditis and previous mechanical AVR (both absolute contraindications to TAVR) were excluded. Patient characteristics and outcomes data were collected prospectively into a dedicated database, which was analyzed retrospectively to determine if patients fit into any of four subgroups designated as exclusion criteria in the low-risk PARTNER 3 trial: 1) NTAV, defined as uni- and bicuspid native aortic valves; 2) severe coronary artery disease (SevCAD), defined as either >50% unprotected left main disease or a SYNTAX score >32; 3) concomitant mitral or tricuspid valve disease (CMTV), with the presence of at least moderate-severe regurgitation or stenosis; and 4) concomitant ascending aorta replacement (CAAR) such as dilation or aneurysms.
Results:
A total of 6,772 patients underwent SAVR for SAS between 2000-2019, 5,310 of which (78%) were considered low surgical risk (mean STS score of 1.94 ± 0.87%). Of these patients, 2,165 (41%) fell into one or more of the following groups: NTAV, SevCAD, CMTV, and CAAR.
NTAV was the most frequent, seen in 1,468 (27.6%) of low-risk patients. Incidence was highest in younger patients. Observed 30-day mortality was 0.9%, lower than the risk estimated by the patients’ STS scores (risk-adjusted mortality ratio, 0.59; 95% confidence interval [CI], 0.34-1.02). Compared to trileaflet valve–matched counterparts, patients with NTAV showed a lower 30-day mortality (adjusted odds ratio [aOR], 0.42; 95% CI, 0.22-0.81; log-rank test: 0.001), lower 1-year mortality (adjusted hazard ratio [aHR], 0.59; 95% CI, 0.38-0.9; p = 0.02), and similar stroke risk (aOR, 0.92; 95% CI, 0.54-1.49; p = 0.69).
The statistics for the other three subgroups were: CAAR–560 patients, or 10.5%; SevCAD–307 patients, or 5.8%; CMTV–306 patients, or 5.8%. Thirty-day mortality for CAAR and SevCAD were 2.1% and 2.6%, similar to that estimated by STS score, while it was 5.9% for CMTV, the only group which showed a higher 30-day mortality than estimated by patient STS score. CMTV was also the only group which showed worse outcomes when compared to patients without concomitant CMTV intervention (30-day mortality aOR, 2.61; 95% CI, 1.5-4.5; 1-year mortality aHR, 2.5; 95% CI, 1.65-3.8; p < 0.001). Stroke risk was not significantly different for CMTV versus non-CMTV (aOR, 0.94; 95% CI, 0.75-0.82; p = 0.13).
Conclusions:
In a real-world cohort of consecutive low-risk SAS patients, judged by a well-established cardiac surgical risk calculator, over 40% fell into at least one subgroup that would have excluded them from enrollment in the PARTNER 3 trial of TAVR versus SAVR.
The NTAV subgroup accounted for the majority of cases (27.6%), followed by CAAR (10.5%), SevCAD, and CMTV (both 5.8%).
The NTAV group had 30-day mortality of only 0.9%, lower than would have been predicted by STS scores and trileaflet–matched counterparts (OR, 0.42; 95% CI, 0.22-0.81).
CAAR and SevCAD also had low 30-day and 1-year mortality, while CMTV was the only subgroup in which mortality exceeded rates predicted by STS scores.
Perspective:
Currently, for low-risk surgical patients, SAVR is still recommended over TAVR, though the more recent low-risk trials (PARTNER 3 and Evolut Low Risk) are showing positive clinical outcomes in low-risk TAVR recipients. However, the fact that nearly half of the low-risk SAVR patients fall into subgroups that were excluded from TAVR versus SAVR clinical trials suggests that caution is needed before expanding the use of TAVR in all low-risk SAS patients. This is particularly relevant for NTAV patients, who make up the largest subgroup, often do not have concomitant surgical needs, and appear to have very low surgical risk in this real-world cohort. Of course, the fact that these patients have fairly good surgical outcomes does not mean that TAVR may not be appropriate, but rather suggests need for randomized trials in this specific subgroup. Furthermore, longer-term follow-up is needed to evaluate not just immediate 1-year post-procedural complications, but also prosthetic degeneration (stenosis or regurgitation) rates over time.
Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Valvular Heart Disease, Atherosclerotic Disease (CAD/PAD), Aortic Surgery, Cardiac Surgery and VHD, Interventions and Coronary Artery Disease, Interventions and Structural Heart Disease, Interventions and Vascular Medicine
Keywords: Aneurysm, Aortic Valve Stenosis, Cardiac Surgical Procedures, Constriction, Pathologic, Coronary Artery Disease, Dilatation, Endocarditis, Mitral Valve Stenosis, Risk, Stroke, Transcatheter Aortic Valve Replacement, Treatment Outcome, Tricuspid Valve Stenosis
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