Mitral Valve Repair in the United States: Single-Center versus Multi-Center Surgeons' Risk-Adjusted Outcomes (13 words, 96 characters).

Background: Healthcare consolidation may force cardiac surgeons to operate at multiple centers. Little data exists as to this phenomenon's effect upon patients' quality of care as measured by risk-adjusted outcome (RAO) rates.

Objectives: To compare mitral valve repair (MVr) RAO rates between surgeons operating at multiple centers (MC) versus single-centers (SC); for MC surgeons, to compare MVr RAO rates between their primary and secondary centers.

Methods: The 2011-2019 Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database's MVr records were analyzed. MC surgeons performed MVr procedures at > 2 centers within a year; each MC surgeon's highest MVr volume ("primary") center was identified. Applying the STS-approved 2018 isolated-MVr risk models, study endpoints included risk-adjusted 30-day major morbidity or mortality (RA-MMM; based on operative death, dialysis, stroke, prolonged ventilation, mediastinitis, or repeat procedure) and prolonged length of stay (RA-PLOS). The impacts of surgeon's and hospital's MVr and total cardiac surgery volumes were evaluated.

Results: Compared to MC surgeons, SC surgeons had lower RA-MMM (OR 1.170, p < 0.001). After adjusting for surgeon and center volumes, this finding persisted (OR 1.141, p = 0.0155). MC surgeons experienced lower RA-MMM at their primary versus secondary centers (OR 1.269, p<.001); this finding was partially due to center-based volume variations (OR 1.130, p=.098). No SC versus MC surgeon RA-PLOS differences were found; however, regional RA-PLOS differences persisted.

Conclusion: Compared to single-center surgeons, reallocating surgeons' caseload across multiple centers has a statistically significant, negative impact on their MVr RAO rates.