How will low-risk TAVR affect lower-volume sites?
More TAVR patients will inevitably mean more U.S. sites offering the procedure, experts agreed. “We anticipate more low-volume programs,” Dr. Carroll said.
Bruce Jancin/Frontline Medical News
Dr. Sreekanth Vemulapalli
“Approval of TAVR for low-risk patients will result in a significant increase in the number of programs offering it. Approximately 1,100 U.S. programs offer SAVR, and as of now about 600 of these programs also offer TAVR. Health systems face the risk of losing patients if they don’t offer TAVR now that low-risk patients can be treated,” observed Sreekanth Vemulapalli, MD, a cardiologist at Duke University, Durham, N.C. who has run several studies using TVT Registry data and serves as liaison between the registry and its analytic center at Duke.
One of these studies, published earlier in 2019, showed that, among more than 96,000 registry patients who underwent transfemoral TAVR during 2015-2017 at 554 U.S. centers, those treated at sites that fell into the bottom quartile for case volume had an adjusted 30-day mortality rate that was 21% higher relative to patients treated at centers in the top quartile, a statistically significant difference (N Engl J Med. 2019 Jun 27;380[26]:2541-50). The absolute difference in adjusted 30-day mortality between the lowest and highest quartiles was 0.54%, roughly 1 additional death for every 200 patients. The TAVR centers in the lowest-volume quartile performed 5-36 cases/year, averaging 27 TAVRs/year; those in the highest quartile performed 86-371 TAVRs annually with an overall quartile average of 143 procedures/year.
Dr. Vemulapalli and others cautioned that TAVR case volume is currently serving as a surrogate, and imperfect, marker for program quality until TAVR programs generate enough data to allow a directly measured, risk-adjusted, outcome-driven assessment of performance. In the study he and his associates published in June, the 140 TAVR programs in the lowest-volume quartile showed a “high” level of variability in their adjusted mortality rates. Despite this limitation, the prospect that new TAVR programs will soon open to meet growing TAVR demand from low-risk patients poses the question of how these programs will perform during their start-up days (and possibly beyond), when case volumes may be light, especially if sites open in more remote sections of the United States.
“Will the real-world results of TAVR in low-risk patients match the fantastic results in the two low-risk TAVR trials?” wondered Dr. Carroll, referring to the PARTNER 3 (N Engl J Med. 2019 May 2;380[18]:1695-1705) and Evolut Low-Risk Patients trial (N Engl J Med. 2019 May 2;380[18]:1706-15). “It’s unknown whether a site just starting to do TAVRs will get the same results. The sites that participated in the low-risk trials were mostly high-volume sites.” On the other hand, TVT Registry data have shown that patients with surgical risk that was judged prohibitive, high, or intermediate all have had overall real-world outcomes that match what was seen in the relevant TAVR trials.
In addition, some experts view a modest drop in 30-day survival among patients treated at lower-volume TAVR sites as a reasonable trade-off for easier access for patients seeking this life-changing treatment.
“We need to ensure that patients have access to this treatment option,” said Catherine M. Otto, MD, professor of medicine and director of the Heart Valve Clinic at the University of Washington, Seattle. The potentially better outcomes produced at larger TAVR programs “need to be balanced against having a greater number of programs to ensure access for more patients and allow patients to be treated closer to home,” she said in an interview. She suggested that the potential exists to use telemedicine to link larger and more experienced TAVR programs with smaller and newer programs to help boost their performance.
Dr. Brian R. Lindman
“There is no perfect solution or metric to ensure high quality while also allowing for adequate access. As indications for TAVR expand we need to maintain vigilance and accountability as the therapy is dispersed to more patients at more centers,” said Brian R. Lindman, MD, medical director of the Structural Heat and Valve Center at Vanderbilt University, Nashville, Tenn. “We also need to insure that certain groups of patients have adequate access to this therapy. Adequate access to TAVR and high-quality clinical outcomes are both important goals.”
Plus, “the volume relationship may be less important,” in lower-risk patients, suggested Dr. Cleveland in an interview. Low-risk patients are younger and have fewer comorbidities and less vascular disease. “Low-volume centers should be able to treat these patients,” he said. Despite that, he personally supported the higher volume minimum for TAVR of 50 cases/year that the ACC, STS, and other U.S. professional societies recommended to CMS during public comment on the proposed rules. “We’ll see whether the increased access is worth this volume minimum.”