In low-volume SAVR centers, 30-day and 1-year mortality are higher with TAVR. So, why does more SAVR make for better TAVR?
Well-established evidence shows a direct correlation between institutional procedural volume of transcatheter aortic valve replacement (TAVR) and patient outcomes. Increasing experience, innovations in valve design and technology, and improvements in patient selection have all combined to produce significant reductions in morbidity and mortality after TAVR.
But is there a relationship between surgical aortic valve replacement (SAVR) volume and TAVR outcomes? Understanding any such relationship certainly would be crucial as the Centers for Medicare & Medicaid Services re-examines minimum volume requirements for its national coverage determination for TAVR.
In a study published in the February issue of JACC: Cardiovascular Interventions, a team of Harvard investigators used a large cohort of fee-for-service Medicare beneficiaries over a 4-year period to analyze all aortic valve replacement procedures: 65,757 SAVR admissions and 42,967 TAVR admissions.
Analyzing the institutions by quartiles of TAVR procedure volume showed a 32% higher risk-adjusted 30-day mortality for TAVR procedures performed at hospitals with the lowest SAVR volumes (<100/year) versus the highest-volume group performing >300 SAVRs/year.
After controlling for age, race, and sex, the adjusted survival differences in TAVR outcomes persisted at 1-year post-procedure.
Why should SAVR volume matter in terms of impacting TAVR outcomes? In an accompanying commentary, Michael J. Mack, MD, and Lars Svensson, MD, noted that the relationship may go back to the care team, which has been required since the U.S. Food and Drug Administration approved TAVR and its use was predicated by the need for a rational dispersion policy.
Mack and Svensson wrote that “a good outcome starts with good decision making” and a patient is optimally managed when all treatment options are available in an institution, when the selected treatment is performed well, and care decisions are made by a multidisciplinary care team. If any aspect of the heart team is deficient (e.g., inexperience in performing SAVR), then patient care suffers.
If sustaining a viable SAVR program with sufficient volume and experience within an institution is vital for optimal TAVR outcomes, that may be tougher in the coming years. As TAVR volume increases, SAVR has held steady or declined since 2011. With the recent FDA approval of TAVR for patients at low surgical risk, U.S. case volume for TAVR will likely rise markedly.
Mack and Svensson think that future studies should determine whether declining SAVR volume adversely affects TAVR outcomes.
They concluded, “Just as having an experienced TAVR program improves SAVR outcomes by treating the highest surgical risk patients, the converse is also true: that better SAVR makes better TAVR.”
The study’s authors wrote that they “strongly believe” that continuing to invest resources and personnel in both SAVR and TAVR programs will be important for overall TAVR outcomes.
Yoshi Kaneko, MD, first author of the Harvard study, told CRTOnline, “It is a critical time for surgeons to assure the quality of SAVR outcome. SAVR is still a better solution for certain patients; but, having poor outcomes will derail the discussion favoring TAVR in these patients. We must embrace the current tide, but at the same time, do everything possible to maintain the quality of SAVR.”
Since there is a substantial delay in data availability, the analysis uses 2012-2015 data. Kaneko said the authors hope to update their paper with more recent CMS data when they become available.
Finally, while the study’s findings did not provide an exact cutoff for a minimal SAVR volume requirement, such a threshold should be explored as an additional metric to evaluate TAVR performance.
Hirji SA, McCarthy E, Kim D, et al. Relationship Between Hospital Surgical Aortic Valve Replacement Volume and Transcatheter Aortic Valve Replacement Outcomes. JACC Cardiovasc Interv 2020;13:335-43.
Mack MJ, Svensson L. Why Does More SAVR Make Better TAVR? JACC Cardiovasc Interv 2020;13:344-5.