Association of Hospital Inpatient Percutaneous Coronary Intervention Volume With Clinical Outcomes After Transcatheter Aortic Valve Replacement and Transcatheter Mitral Valve Repair

Key Points

Question  Is there an association between hospital percutaneous coronary intervention (PCI) volume and transcatheter aortic valve replacement and transcatheter mitral valve repair outcomes?

Findings  In this cross-sectional study, there was no association between hospital inpatient PCI volume and median transcatheter aortic valve replacement risk-standardized in-hospital mortality or 30-day readmission rates. Similarly, there was no association between hospital inpatient PCI volume and median transcatheter mitral valve repair risk-standardized in-hospital mortality or 30-day readmission rates.

Meaning  Further evidence is needed to support inclusion of PCI volume minimums in national coverage determination requirements for hospital transcatheter aortic valve replacement and transcatheter mitral valve repair programs.

Importance  The US Centers for Medicare and Medicaid Services recently released an updated national coverage determination proposal for transcatheter aortic valve replacement (TAVR) that maintains a focus on hospital TAVR volume and percutaneous coronary intervention (PCI) volume, and the national coverage determination for transcatheter mitral valve repair (TMVr) also has PCI volume requirements. However, the associations between hospital PCI volume and TAVR and TMVr outcomes are unknown.

Objective  To investigate whether hospital inpatient PCI volume is associated with rates of risk-adjusted in-hospital mortality and 30-day hospital readmission after TAVR and TMVr.

Design, Setting, and Participants  This population-based cross-sectional study of the 2016 Nationwide Readmissions Database included procedures completed in hospitals with a minimum of 5 TAVR or 5 TMVr procedures between January 1, 2016, and November 30, 2016.

Exposures  Hospitals were divided into quartiles based on annual inpatient PCI volumes.

Main Outcomes and Measures  Primary outcomes were in-hospital mortality and 30-day readmission rates. The associations between hospital inpatient PCI quartile and outcomes were evaluated using Kruskal-Wallis tests. Risk adjustment for in-hospital mortality rates was done through inclusion of variables based on the Elixhauser comorbidity classification, and risk adjustment for 30-day readmission rates was done in accordance with the Hospital-Wide Readmission Measure methodology used by the Centers for Medicare and Medicaid Services for public reporting.

Results  There were 283 hospitals that performed at least 5 TAVRs, with a median inpatient PCI volume of 386 (interquartile range, 299-571) procedures, and 125 hospitals that performed at least 5 TMVr procedures, with a median inpatient PCI volume of 451 (interquartile range, 326-651) procedures. There was no association between hospital inpatient PCI volume and median TAVR risk-standardized in-hospital mortality (median [IQR] rates: bottom quartile, 1.82% [1.77%-1.90%]; second quartile, 1.81% [1.76%-1.86%]; third quartile, 1.81% [1.75%-1.90%]; top quartile, 1.82% [1.76%-1.91%]; P = .75) or the 30-day readmission (median [IQR] rates: bottom quartile, 13.6% [13.2%-14.3%]; second quartile, 13.3% [12.7%-14.0%]; third quartile, 13.5% [12.7%-14.3%]; top quartile, 13.8% [12.8%-14.3%]; P = .10) rates. Similarly, there was no association between hospital inpatient PCI volume and median TMVr risk-standardized in-hospital mortality rates (median [IQR] rates: bottom quartile, 1.84% [1.47%-2.53%]; second quartile, 1.65% [1.21%-3.02%]; third quartile, 1.80% [1.52%-3.58%]; top quartile, 1.76% [1.33%-4.20%]; P = .71) or 30-day readmission rates (median [IQR] rates: bottom quartile, 13.4% [13.1%-13.6%]; second quartile, 13.1% [12.9%-13.5%]; third quartile, 13.1% [12.9%-13.5%]; top quartile, 13.3% [12.8%-13.6%]; P = .30).

Conclusions and Relevance  In this study, there was no association between inpatient PCI volume and TAVR or TMVr outcomes. Further evidence is needed to support inclusion of PCI volume minimums in national coverage determination requirements for hospital TAVR and TMVr programs.

The Centers for Medicare and Medicaid Services (CMS) recently released an updated national coverage determination for transcatheter aortic valve replacement (TAVR) that maintains a focus on minimum percutaneous coronary intervention (PCI) volume for hospitals performing TAVR.¹ The national coverage determination for transcatheter mitral valve repair (TMVr) using the MitraClip (Abbott) system is being revised and currently also includes PCI volume requirements.² In the context of structural heart intervention, the evidence evaluating the volume-outcomes association is still emerging. While associations between hospital TAVR and TMVr volumes and outcomes have been evaluated,^3-5 the association between PCI volume with TAVR and TMVr outcomes remains unknown. Although hospital PCI volume may be considered a surrogate for the presence of resources and local expertise to deal with unanticipated complications and TAVR-associated coronary issues,⁶ TMVr-associated coronary complications are minimal with current systems. Given that hospital PCI volume thresholds have been set by CMS for TAVR and TMVr programs, we sought to investigate whether hospital inpatient PCI volume is associated with rates of risk-adjusted in-hospital mortality and 30-day readmission after TAVR and TMVr procedures.

Data from the Healthcare Cost and Utilization Project 2016 Nationwide Readmission Database were used, which account for 49% of US hospitalizations. Hospitals that performed a minimum of 5 TAVR procedures (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision [ICD-10] codes 02RF37Z, 02RF38Z, 02RF3JZ, 02RF3KZ, 02RF37H, 02RF38H, 02RF3JH, and 02RF3KH) or 5 TMVr procedures (ICD-10 codes 02RG3JZ, 02RG4JZ, 02QG3ZZ, 02QG4ZZ, 02UG3JZ, 02UG4JZ, 02WG3JZ, and 02WG4JZ) in 2016 were included.

This study was exempt from institutional review board review, given that it was a retrospective analysis of preexisting, publicly available, deidentified data. These features also precluded collection of informed consent.

The primary exposure was hospital inpatient PCI volume in 2016 (between January 1, 2016, and November 30, 2016). The coprimary outcomes were median hospital risk-adjusted in-hospital mortality and median hospital risk-adjusted 30-day readmission rates. For readmission rates, similar to algorithms used by CMS,⁷ index hospitalizations with an in-hospital death, discharge against medical advice, or transfer to another acute care facility were excluded. Only the first readmission within 30 days of the index hospitalization was considered.

Risk adjustment for mortality was undertaken using variables based on the Elixhauser comorbidity classification.⁸ Risk adjustment for readmission was undertaken in accordance with the Hospital-Wide Readmission Measure methodology,⁹ although primary diagnosis was excluded because of small samples, and variables with less than 10% or more than 90% incidence were dropped.

We created 2 cohorts of hospitals to evaluate TAVR and TMVr separately based on whether they had performed at least 5 procedures. We tested correlations between inpatient PCI volume and TAVR and TMVr volumes using Spearman coefficients.

We used cubic spline models with 3 evenly spaced knots to model inpatient PCI volume as a continuous variable to assess for nonlinearity visually. We then divided hospitals into quartiles based on their annual inpatient PCI volumes. We used Kruskal-Wallis tests to evaluate the association of inpatient PCI volume quartile with TAVR and TMVr outcomes while undertaking risk adjustment as specified. In supplemental analyses, we examined the mean of the median structural heart intervention hospital length of stay across inpatient PCI volume quartiles and compared structural heart intervention volumes and outcomes between the bottom quartile and top 3 quartiles of inpatient PCI volumes. All analyses were performed between May 2019 and November 2019 using SAS version 9.4 (SAS Institute). A 2-sided P value of .05 was used as the threshold for statistical significance.

A total of 283 hospitals performed at least 5 TAVRs, with a median inpatient PCI volume of 386 (interquartile range, 299-571) procedures, and 125 hospitals performed at least 5 TMVrs, with a median inpatient PCI volume of 451 (interquartile range, 326-651) procedures (eFigures 1-5 in the Supplement). Hospital characteristics by inpatient PCI volume quartile are detailed in the eTable in the Supplement. There was a moderate correlation between inpatient PCI volume and TAVR volume (Spearman ρ, 0.47) and a weak correlation between inpatient PCI volume and TMVr volume (Spearman ρ, 0.15). Cubic spline models of inpatient PCI volume and TAVR and TMVr outcomes showed nonlinearity (Figure 1).

There was no association between hospital inpatient PCI volume and the median TAVR risk-standardized in-hospital mortality rate (median [IQR] rates: bottom quartile, 1.82% [1.77%-1.90%]; second quartile, 1.81% [1.76%-1.86%]; third quartile, 1.81% [1.75%-1.90%]; top quartile, 1.82% [1.76%-1.91%]; P = .75; Figure 2A) or the 30-day readmission rate (median [IQR] rates: bottom quartile, 13.6% [13.2%-14.3%]; second quartile, 13.3% [12.7%-14.0%]; third quartile, 13.5% [12.7%-14.3%]; top quartile, 13.8% [12.8%-14.3%]; P = .10; Figure 2B). Similarly, there was no association between hospital inpatient PCI volume and the median TMVr risk-standardized in-hospital mortality rate (median [IQR] rates: bottom quartile, 1.84% [1.47%-2.53%]; second quartile, 1.65% [1.21%-3.02%]; third quartile, 1.80% [1.52%-3.58%]; top quartile, 1.76% [1.33%-4.20%]; P = .71; Figure 3A) or the 30-day readmission rate (median [IQR] rates: bottom quartile, 13.4% [13.1%-13.6%]; second quartile, 13.1% [12.9%-13.5%]; third quartile, 13.1% [12.9%-13.5%]; top quartile, 13.3% [12.8%-13.6%]; P = .30; Figure 3B).

In supplemental analyses, there were lower TAVR volumes in the bottom quartile of PCI volume compared with the top 3 quartiles (medians [interquartile ranges]: bottom quartile, 40 [24-76] procedures; top 3 quartiles, 67 [37-127] procedures; P < .001; eFigure 6 in the Supplement), but no significant differences in TMVr volumes or structural heart intervention outcomes (eFigures 7-11 in the Supplement). Additionally, there was no difference in the mean of median hospital length of stay after structural heart intervention across inpatient PCI volume quartiles (eFigures 12 and 13 in the Supplement).

This study adds to the understanding of cardiovascular procedure volume–outcome associations. We found no associations between inpatient PCI volume and TAVR and TMVr outcomes. While higher hospital TAVR volume is known to be associated with a lower risk-adjusted 30-day mortality rate after transfemoral TAVR,³ and increased hospital procedural experience with TMVr is associated with improved procedural success and fewer complications,⁵ the association between volumes of other cardiovascular procedures and structural heart procedure outcomes is less clear. Hospital surgical aortic valve replacement volume, for example, was not associated with TAVR outcomes in Medicare patients between 2011 and 2015.⁴ This study is the first (to our knowledge) to investigate whether inpatient PCI volume is associated with structural heart procedural outcomes and find no association between the 2 metrics.

These findings have important policy implications. The US Centers for Medicare and Medicaid Services currently requires 300 or more PCIs annually for a hospital to initiate and maintain a TAVR program and 400 or more PCIs annually for a hospital to initiate and maintain a TMVr program.^1,2 The justification for inclusion of PCI volume requirements has been to ensure that hospitals possess the infrastructure and skills required to deal with coronary and other complications of often-complex structural heart procedures.⁶ Although TAVR-associated coronary issues may require such expertise, there is very low risk of coronary complications with current TMVr systems. Furthermore, such volume thresholds in the national coverage determination can potentially incentivize hospitals to perform unnecessary procedures. Notably, in response to questions regarding TAVR volume requirements, the Medicare Evidence Development and Coverage Advisory Committee was least confident in stating that the benefits of meeting procedural volume requirements to begin a TAVR program outweighed the harms of limiting access to TAVR to only those hospitals that met volume requirements.¹⁰ The lack of evidence supporting an association between PCI volume and structural heart disease procedure outcomes suggests the need to reconsider minimum PCI volume requirements and a further need to target other requirements directly linked to quality of care and clinical outcomes.

This study should be interpreted in context of its limitations. First, the Nationwide Readmission Database only contains data from inpatient admissions and does not contain information about 11.9% of PCI procedures that occur in the outpatient setting.¹¹ The PCI volumes expressed here therefore are not exactly the same as those used for the national coverage determination thresholds, but our analysis clearly demonstrates a lack of associations between inpatient PCI volume and outcomes after TAVR and TMVr. Second, we excluded hospitals performing fewer than 5 TAVR or TMVr procedures, which may limit the generalizability of our findings to hospitals with extremely low volumes. Third, the use of in-hospital mortality and all-cause readmission rates after TAVR and TMVr have not been validated as hospital performance metrics. Fourth, all hospitals should already meet minimum PCI thresholds required by CMS, and the findings may not extend to hospitals not meeting these thresholds.

In conclusion, we found no association between inpatient PCI volumes and TAVR or TMVr outcomes. Policy makers should reconsider the rationale and utility of the minimum PCI volume requirement for structural heart disease interventions.

Accepted for Publication: December 13, 2019.

Corresponding Author: Sammy Elmariah, MD, MPH, Cardiology Division, Department of Medicine, Massachusetts General Hospital, 55 Fruit St, Bigelow 815, Boston, MA 02114 (selmariah@mgh.harvard.edu).

Published Online: February 12, 2020. doi:10.1001/jamacardio.2019.6093

Author Contributions: Drs Butala and Bucholz had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: All authors.

Acquisition, analysis, or interpretation of data: Butala, Kolte, Elmariah.

Drafting of the manuscript: Butala, Elmariah.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Butala, Bucholz.

Administrative, technical, or material support: Kolte, Elmariah.

Supervision: Elmariah.

Conflict of Interest Disclosures: Dr Elmariah reported grants from Edwards Lifesciences and personal fees from AstraZeneca outside the submitted work. Dr Butala reported consulting fees from HiLabs outside the submitted work. No other disclosures were reported.

Funding/Support: Dr Butala is funded by the John S. LaDue Memorial Fellowship at Harvard Medical School.

Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.