Hospitals that performed more transcatheter aortic valve replacements continued to outperform low-volume centers for 30-day postprocedure survival, in data collected from more than 113,000 transcatheter aortic valves replaced during 2015-2017.
Bruce Jancin/MDedge News
Dr. Sreekanth Vemulapalli
During that time, 113,662 transcatheter aortic valve replacement (TAVR) procedures occurred in the United States and were entered into a registry maintained by the Society of Thoracic Surgeons and American College of Cardiology. The new analysis focused on the more than 96,000 valve placements done via a transfemoral approach. The analysis divided these patients into quartiles based on total annual TAVR volume at each of the 554 centers where the procedures occurred, and this showed that 30-day mortality, after adjustment for 39 demographic and clinical variables, was 3.19% among patients treated at centers in the lowest-volume quartile and 2.66% in patients treated at centers in the highest-volume quartile. This translated to a 21% relative risk increase in 30-day mortality at the lowest volume centers that was statistically significant, Sreekanth Vemulapalli, MD, and his associates reported in an article published online on April 3 in the New England Journal of Medicine.
The mean annual volume among centers in the lowest-volume quartile during the 3 years studied was 27 procedures/year, while the average volume among the 25% highest-volume centers was 143 TAVRs each year, reported Dr. Vemulapalli, an interventional cardiologist at Duke University in Durham, N.C., and his associates. After excluding the first 12 months of TAVR performance for each center during the study period, the adjusted 30-day mortality averaged 3.10% in the lowest-volume tertile and 2.61% in centers in the highest-volume tertile. That meant the lowest-volume centers saw a 19% relative increase in mortality that was statistically significant.
This is not the first study to show a significant link between TAVR procedure volumes at individual centers and patient outcomes, and since 2012 the Centers for Medicare & Medicaid Services has stipulated that eligibility for Medicare coverage of TAVR requires that it be done at a center that performs at least 20 TAVR procedures annually or at least 40 during the most recent 2 years. A prior report showing a similar volume-outcome link looked at U.S. TAVR cases during 2011-2015 (J Am Coll Cardiol. 2017 July;70[1]:29-41), and reports of volume-outcome relationships have also come out for other catheter-based intravascular procedures.
“Our results suggest that raising the minimum volume requirements for TAVR centers may improve the quality of outcomes. However, this potential improvement in quality needs to be balanced against access to care in general, and for underserved and underrepresented populations in particular,” Dr. Vemulapalli said in an interview. The data suggested that a significant number of patients from underserved populations are treated at lower-volume TAVR centers. It’s unclear what impact raising the threshold volume [by CMS] might have on these underserved populations,” he explained.
Dr. Vemulapalli conceded that his analysis may have been affected by several potential confounding variables that did not receive adjustment in the analyses he and his associates ran. The variables of hospital size and teaching status both showed an association with TAVR volume. Hospitals with a greater number of beds and those that were teaching hospitals were also the places where TAVR volumes were highest, while lower-volume centers tended to be smaller, nonteaching institutions. But the variables of size and teaching status did not receive adjustment. Both are “difficult to tease apart from TAVR volume,” he noted.
The CMS mandated Transcatheter Valve Therapy Registry also functions as a quality-improvement mechanism in which U.S. TAVR sites receive quarterly feedback on their performance and are benchmarked against other programs in a risk-adjusted way. The registry also disseminates best practices as part of the quality improvement process, Dr. Vemulapalli said.
Results from two TAVR trials reported at the American College of Cardiology’s annual meeting in March, PARTNER 3 and Evolut Low Risk, documented the efficacy and safety of TAVR compared with surgery in low-risk patients, findings that will soon substantially increase the volume of TAVR cases performed (N Engl J Med. 2019 Mar 16. doi: 10.1056/NEJMoa1814052 and doi: 10.1056/NEJMoa1816885).
When the impact of TAVR moving to low-risk patients starts to kick in, “the findings from our analysis will become even more relevant,” Dr. Vemulapalli predicted. “As TAVR moves to low-risk, healthier patients, and more patients undergo the procedure, a firm commitment to measuring and ensuring quality while balancing access to care will be pivotal. The data in our study regarding the association between TAVR volume and outcomes and the characteristics of low- and high-volume hospitals and the patients they treat are fundamental to striking this balance.”
SOURCE: Vemulapalli S. et al. N Engl J Med. 2019 Apr 3.doi: 10.1056/NEJMsa1901109.