Is There a Volume-Outcome Relationship in TAVR?

A volume-outcomes relationship may not exist for current generation balloon-expandable valves after the initial learning curve of about 200 cases, and therefore all TAVR centers should be able to "achieve consistently excellent outcomes," according to a study published Jan. 28 in the Journal of the American College of Cardiology.

Mark J. Russo, MD, MS, et al., used data from the STS/ACC TVT Registry to determine whether a volume-outcomes relationship persisted for balloon-expandable TAVR after the initial learning curve, and whether the learning curve and volume-outcomes relationship differed for different device generations. The researchers analyzed data from 61,949 balloon-expandable valve implants. The study's primary outcomes included 30-day all-cause mortality, stroke and major vascular complications. To determine when the learning curve ended, the researchers looked at all implants chronologically and then assessed the volume-outcomes relationship by examining the monthly case volume at each center. The researchers repeated the analysis separately for all balloon-expandable valve types, Sapien 3 only, and Sapien 3 at sites without prior experience implanting balloon-expandable valves.

Results showed that for all valve types, sites experienced an initial learning curve that ended after about 200 cases. After that point, there was no relationship between volumes and outcomes. In addition, there was no learning curve or volume-outcomes relationship for Sapien 3 only or for Sapien 3 at sites without prior experience.

The researchers conclude that with further refinement in procedural techniques, sharing of best practices, ongoing case support and improvements in device technology, excellent outcomes should be expected with balloon-expandable valves, even at centers without prior experience, and excellent outcomes should be sustainable regardless of a center's case volume.

In an accompanying editorial commentary, Saif Anwaruddin, MD, FACC, and Matthew D. Saybolt, MD, FACC, write that while outcomes are good at many low-volume centers, "it should be incumbent upon governing bodies, industry, and other stakeholders to partner with lower-performing sites to build on experience and improve processes of care." They add that additional work is still needed to "better assess and improve upon quality and outcomes in TAVR across all sites in the best interest of our patients."

Keywords: Transcatheter Aortic Valve Replacement, Registries, Outcome Assessment, Health Care, Stroke, Aortic Valve Stenosis, National Cardiovascular Data Registries, STS/ACC TVT Registry

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