How to Build a Better TAVR

In cardiovascular medicine, practice may not make perfect, but experience certainly improves outcomes. In numerous contexts, data confirm that larger volume and greater experience correlate with reduced complication rates. In the setting of primary percutaneous coronary intervention (PCI) for acute myocardial infarction, it is well documented that higher annual hospital and operator volume is associated with lower mortality.¹ The same phenomenon has been documented with respect to complex surgical procedures.² As would be expected, TAVR is no exception to this rule. In a study employing National Inpatient Sample (NIS) data, Badheka et al divided hospitals into quartiles based on TAVR volume and found that inpatient mortality, complication rates, length of stay (LOS), and hospital costs all declined with increasing TAVR volume.³  

With this background in mind, in this issue of the Journal of Invasive Cardiology, Pant et al have examined the relationship between hospital type (academic vs non-academic) and TAVR outcomes.⁴ Using NIS data, they evaluated 7405 TAVRs performed during the calendar year of 2012, 88% of which were performed at teaching hospitals with the remaining 12% at non-teaching hospitals. They appropriately defined teaching hospitals as those with residency programs with inherent strict standards relating to volume of procedures, a core of teaching faculty, and a curriculum for research and education. Their findings demonstrated no difference in TAVR mortality between the teaching and non-teaching centers. However, they did find lower complication rates at teaching hospitals. The question that naturally arises is whether this finding is merely a reflection of the above-noted underlying principle that experience improves outcomes. After all, 6540 of the 7405 TAVRs were performed at teaching centers. 

But, there may be more to their findings. Given that 2012 was the first full year of Food and Drug Administration (FDA)-approved commercially available TAVR, many of the teaching centers – unless they had participated in the PARTNER Trial – may not have had any more experience than non-teaching centers. One can speculate that the presence of residents around-the-clock at teaching hospitals may have resulted in earlier identification of problems in the postprocedure period, thereby allowing the academic centers to rapidly identify and treat some complications. On the other hand, one could also speculate that the larger volume at teaching centers allowed academic practitioners to ascend their learning curve faster than their colleagues in non-teaching centers, thereby minimizing complications as the year progressed. In other words, the larger volume at teaching hospitals may have allowed academic practitioners to suffer the same number of complications early in their learning curve but enjoy a lower complication rate overall. 

In either case, this study’s findings raise larger questions regarding the growth and development of TAVR. TAVR is a transformational technology that offers a promising therapeutic option to many previously untreatable patients. The technology, as well as the “heart team” approach, was tested in a thoughtfully crafted and meticulously executed randomized controlled clinical trial – the PARTNER trial. Replicating the outcomes achieved in the PARTNER trial in the larger real-world requires, as Michael J. Mack and David R. Holmes have commented, the “safe and rational dispersion of new technology.”⁵ The joint efforts of multiple societies including the Society for Cardiovascular Angiography and Interventions (SCAI), the American College of Cardiology (ACC), the American Association for Thoracic Surgery (AATS), and the Society of Thoracic Surgeons (STS), all working in cooperation with the Centers for Medicare & Medicaid Services (CMS), resulted in CMS issuing a national coverage decision codifying a uniform national policy for operator and institutional requirements for performing TAVR. By setting a high bar in terms of operator and institutional experience, creating multidisciplinary educational programs, and establishing the Transcatheter Valve Therapy (TVT) registry to track procedures and outcomes, the hope has been to slowly and carefully roll out transcatheter valve procedures to the broader cardiovascular community at large.

While safe and rational dispersion of this technology is important, it must also be balanced against the need to provide appropriate access to care for the affected patient population.⁶ While it may be best from an outcomes standpoint to concentrate TAVR in a small number of extremely high-volume centers, many patients in smaller towns and rural or outlying areas may not have access to such centers. This is particularly true in the setting of valvular heart disease, where much of the population in need of treatment is elderly and frail and therefore cannot easily travel to specialized metropolitan centers. The solution may be the development of regional systems for TAVR care. 

In a recent article, the pioneers of TAVR in North America described their experience and their outcomes with the creation of a hub-and-spoke model for TAVR care in British Columbia.⁷ With a central site in Vancouver, this group developed three other provincial sites. All cases in the region were risk stratified and a coordinated plan developed, with lower-risk procedures being performed at the provincial sites while more complex procedures were referred into the central site. These authors note both good outcomes and reasonably equitable access to care for patients in their region. Just as regional systems of care have been employed to maximize efficiency in the care of other common cardiovascular conditions such as acute myocardial infarction, cardiac arrest, and stroke, so too may regional systems of care be applied to TAVR. In the end, the goal is to provide efficient, cost-effective care that results in optimal outcomes with appropriate access. 

Data from the TVT registry demonstrate the exponential rise in the number of TAVR procedures being performed throughout the United States. From 4590 TAVRs at 156 sites in 2012, the TAVR volume has grown to 26,414 procedures at 348 sites in 2014.⁸ As this rapid growth occurs and continues to swell with the probable expansion to intermediate-risk patients later this year, the goal must be to maintain quality outcomes regardless of whether the procedure is being performed in a non-teaching facility, a newly developing TAVR program, or a teaching hospital with a long-established track record in TAVR. While it may not be possible to replicate the more structured British Columbian system, a more informal hub-and-spoke model in which objective risk stratification is employed, with lower-risk cases being treated peripherally and more complex care being treated centrally, may well develop in the United States. Only time will tell how we can build a better national system for TAVR.

References

1.    Kontos MC, Wang Y, Chaudhry SI, Vetrovec GW, Curtis J, Messenger J. Lower hospital volume is associated with higher in-hospital mortality in patients undergoing primary percutaneous coronary intervention for ST-segment-elevation myocardial infarction. Circ Cardiovasc Qual Outcomes. 2013;6:659-667.

2.    Finks JF, Osborne NH, Birkmeyer JD. Trends in hospital volume and operative mortality for high-risk surgery. N Engl J Med. 2011;36:2128-2137.

3.    Badheka AO, Patel NJ, Panaich SS, et al. Effect of hospital volume on outcomes of transcatheter aortic valve implantation. Am J Cardiol. 2015;116:587-594.

4.    Pant S, Patel S, Golwala H, et al. Transcatheter aortic valve replacement complication rates in teaching vs non-teaching centers in the United States. J Invasive Cardiol. 2016;28:67-70.

5.    Mack MJ, Holmes DR, Webb J, Cribier A, Kodali SK, William MR. Patient selection for transcatheter aortic valve replacement. J Am Coll Cardiol. 2013;62:S1-S10.

6.    Mack MJ. Balancing optimal outcomes with access to care: it can be done! JACC Cardiovasc Interv. 2015;8:1952-1953.

7.    Stub D, Lauck S, Lee M, et al. Regional systems of care to optimize outcomes in patients undergoing transcatheter aortic valve replacement. JACC Cardiovasc Interv. 2015;8:1944-1951.

8.    Holmes DR, Nishimura RA, Grover FL, et al. Annual outcomes with transcatheter valve therapy: from the STS/ACC TVT Registry. J Am Coll Cardiol. 2015;66:2813-2823.

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From ¹the University of Texas Health Science Center Houston at the Memorial Hermann Texas Medical Center Heart and Vascular Institute, Houston, Texas; and ²Saint Louis University School of Medicine, St. Louis, Missouri. 

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Address for correspondence: H. Vernon Anderson, MD, Professor of Cardiology, University of Texas – Houston, 6431 Fannin, Suite 1.246, Houston, TX 77030. Email: h.v.anderson@uth.tmc.edu