The Volume-Outcome Relationship for TAVR in a U.S. Registry

Summary and Comment |
August 2, 2017

The Volume-Outcome Relationship for TAVR in a U.S. Registry

  1. Howard C. Herrmann, MD

Increased site experience with transcatheter aortic-valve replacements is associated with better in-hospital outcomes.

  1. Howard C. Herrmann, MD

More than 500 U.S. hospitals are now performing transcatheter aortic-valve replacement (TAVR), and all are required to report cases and outcomes to the national Society of Thoracic Surgeons/American College of Cardiology's Transcatheter Valve Therapy (TVT) Registry. The present analysis of this registry examines the relationship between site volume and in-hospital outcomes in ≈43,000 commercial procedures performed between November 2011 and November 2015 at 395 sites (NCT01737528).

Associations Between TAVR Volumes and Mortality
The authors assessed the degree to which volume of TAVR procedures is associated with outcomes, shown here for mortality. The plot shows continuous volume using the case sequence approach versus the rate of adverse outcomes including both unadjusted (orange) and risk-adjusted (blue) frequency of these outcomes. The association between volume and mortality is statistically significant for all unadjusted and adjusted outcomes. The P-value for linearity suggests a nonlinear relationship when P is less than 0.05. The orange- and blue-colored bands represent 95% confidence limits.Reprinted from JACC: Journal of the American College of Cardiology, vol 70, Carroll et al., Procedural Experience for Transcatheter Aortic Valve Replacement and Relation to Outcomes, Pages 29–41, Copyright 2017, with permission from Elsevier.
Associations Between TAVR Volumes and Mortality

The authors assessed the degree to which volume of TAVR procedures is associated with outcomes, shown here for mortality. The plot shows continuous volume using the case sequence approach versus the rate of adverse outcomes including both unadjusted (orange) and risk-adjusted (blue) frequency of these outcomes. The association between volume and mortality is statistically significant for all unadjusted and adjusted outcomes. The P-value for linearity suggests a nonlinear relationship when P is less than 0.05. The orange- and blue-colored bands represent 95% confidence limits.

Reprinted from JACC: Journal of the American College of Cardiology, vol 70, Carroll et al., Procedural Experience for Transcatheter Aortic Valve Replacement and Relation to Outcomes, Pages 29–41, Copyright 2017, with permission from Elsevier.

Comparisons were made based on each site's case sequence, which accounts for each institution's learning curve. In most cases, TAVR was performed electively (91%), with general anesthesia (92%) and a transfemoral approach (71%). Unadjusted in-hospital outcomes included mortality (4%), vascular complications (7%), and stroke (2%). Increasing TAVR volumes were associated with decreasing risk-adjusted mortality (see accompanying illustration) and vascular complications, but not stroke. Adverse outcomes continued to decline even after the 100th case, although the confidence intervals were broader at high volumes because few sites had high TAVR volumes and the absolute rates of complications were low.

Comment

The inverse association between experience and adverse outcomes observed for most procedures is clearly demonstrated for TAVR in this large registry and, surprisingly, continues even beyond 100 cases. Although these data cannot determine an exact cutoff for institutional or operator requirements for TAVR, it helps to inform physicians and patients. In addition, the findings should promote societal discussion around the need to expand TAVR to more sites and the potential optimization of care through regionalization and centers of excellence.

Frederick A. Masoudi, MD, MSPH, FACC, FAHA, is an author of this study and a member of the NEJM Journal Watch Cardiology board but had no role in selecting or summarizing this article.

Editor Disclosures at Time of Publication

  • Disclosures for Howard C. Herrmann, MD at time of publication Consultant / Advisory board Leerink Swann; Wells Fargo; Edwards Lifesciences; BMO Capital Markets Equity Micro Interventional Devices, Inc. Grant / Research support Abbott Vascular; Bayer; Boston Scientific; Corvia; Edwards Lifesciences; St. Jude Medical; Medtronic; Cardiokinetix; University of Laval Editorial boards Catheterization and Cardiovascular Interventions; Circulation: Cardiovascular Interventions; Journal of Interventional Cardiology; Journal of Invasive Cardiology; Journal of the American College of Cardiology

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