Effect of Hospital Volume on Outcomes of Transcatheter Mitral Valve Repair: An Early US Experience

Racial Disparities in Access to High-Volume Mitral Valve Transcatheter Edge-to-Edge Repair Centers

Background

Severe mitral regurgitation is a progressive disease associated with high morbidity and mortality, and frequent readmissions for heart failure. Surgical mitral valve repair or replacement has been the gold-standard treatment; however, advances in transcatheter edge-to-edge repair (TEER) have provided alternatives for high-risk surgical patients. There are no data on racial disparities in access to high-volume TEER centers.

Methods

Data on TEER hospitalizations from New York, New Jersey, Maryland, North Carolina, Washington, Colorado, Arizona, and Florida were analyzed using the State Inpatient Databases for 2016. The baseline characteristics of patients who underwent TEER at high- (≥25 procedures per year) and low-volume centers were identified. The association between race and the likelihood of undergoing TEER at high-volume centers was assessed. The secondary outcomes were mortality and the frequency of home discharges.

Results

Of 1567 patients included in the analysis, 1129 underwent TEER at high-volume centers. Patients treated at high-volume centers had a higher prevalence of chronic kidney disease and congestive heart failure. Black and Hispanic patients were 59% (adjusted odds ratio [OR], 0.41; P < .001) and 51% (adjusted OR, 0.49; P < .001) less likely to undergo TEER at high-volume centers, respectively, compared with White patients. Hispanic patients were 3 times more likely to die during index admission than White patients (adjusted OR, 3.32; P = .027). There was geographic clustering of TEER centers, and a higher ratio of White patients to minority patients in zip codes with high-volume TEER centers.

Conclusions

Racial minorities patients, particularly Black and Hispanic patients, are less likely to undergo TEER at high-volume centers. Hispanic patients experience higher rates of in-hospital mortality after TEER than White patients.

Effect of Operator Experience on Transcatheter Mitral Valve Repair Outcomes

Transcatheter mitral valve repair with MitraClip is a novel, intricate therapy for mitral regurgitation that improves survival and quality of life. Similar to other medical procedures, there is a relationship between procedural experience and clinical outcomes. MitraClip results and the efficiency and safety of the procedure all improved with increasing experience at both the institutional and operator level in two large studies from the Society of Thoracic Surgeons and American College of Cardiology Transcatheter Valve Therapy Registry. Patient selection was also found to have a significant role in procedure success. The old adage of "See one, do one, teach one" does not necessarily apply to complex interventions, such as MitraClip, given that the learning curve does not appear to plateau even as operators approach a 150-case experience.

Unconventional Volume-Outcome Associations in Adult Extracorporeal Membrane Oxygenation in the United States

BACKGROUND

The aim of this study was to evaluate institutional volume-outcome relationships in extracorporeal membrane oxygenation (ECMO) with subanalyses of ECMO in patients with a primary diagnosis of respiratory failure.

METHODS

All institutions with adult ECMO discharges in the Nationwide Inpatient Sample from 2002 to 2011 were evaluated. International Classification of Diseases (ninth revision) codes were used to identify ECMO-treated patients, indications, and concurrent procedures. Patients who were treated with ECMO after cardiotomy were excluded. Annual institutional and national volume of ECMO hospitalizations varied widely, hence the number of ECMO cases performed at an institution was calculated for each year independently. Institutions were grouped into high-, medium-, and low-volume terciles by year. Statistical analysis included hierarchical, multivariable logistic regression.

RESULTS

The in-hospital mortality rates for ECMO admissions at low-, medium-, and high-volume ECMO centers were 48% (n = 467), 60% (n = 285), and 57% (n = 445), respectively (p = 0.001). In post hoc pairwise comparisons, patients in low-volume hospitals were more likely to survive to discharge compared with patients in medium-volume (p = 0.001) and high-volume (p = 0.005) hospitals. There was no significant difference in survival between medium-volume and high-volume hospitals (p = 0.81). In a subanalysis of patients with respiratory failure, low-volume ECMO centers maintained the lowest rates of in-hospital mortality (47%), versus 61% in medium-volume institutions (p = 0.045) and 56% in high-volume institutions (p = 0.15). Multivariable logistical regression produced similar results in the entire study sample and in patients with respiratory failure.

CONCLUSIONS

ECMO outcomes in the Nationwide Inpatient Sample do not follow a traditional volume-outcome relationship, and these results suggest that, in properly selected patients, ECMO can be performed with acceptable results in U.S. centers that do not perform a high volume of ECMO.