Hospital and Surgeon Surgical Valvar Volume and Survival after Multi-Valve Cardiac Surgery in Medicare Beneficiaries.

OBJECTIVE: Long-term outcomes after multi-valve cardiac surgery remain under-evaluated.

METHODS: Medicare administrative claims from 2008-2019 identified beneficiaries undergoing multi-valve surgery. Operative characteristics were doubly-adjudicated using International Classification of Diseases and Current Procedural Technology codes. A multivariable flexible parametric model evaluated predictors of survival; regression standardization was performed to predict standardized survival probabilities (SSP) at varying percentiles of annual valvar volume.

RESULTS: Of 476,092 cardiac surgeries involving the aortic (AVS), mitral (MVS), or tricuspid (TVS) valve, 63,083 (13.3%) were identified as involving multi-valve surgery: 22,884 MVS+TVS, 30,697 AVS+MVS, 3,443 AVS+TVS and 6,059 AVS+MVS+TVS. Surgery occurred at 1,157 hospitals by 2,922 surgeons. Annual valvar volume (total AVS+MVS+TVS) was tallied for surgeons and hospitals. Median survival varied substantially by type of multi-valve surgery: 8.09 [7.90-8.24] years in MVS/TVS, 6.65 [6.49-6.81] years in AVS/MVS, 5.77 [5.37-6.13] in AVS/TVS, and 6.02 [5.64-6.38] in AVS/MVS/TVS. SSPs were calculated across combined hospital/surgeon volume percentiles; the median SSP increased with increasing percentile of combined hospital/surgeon volume: 5%tile: 5.77 [5.58,5.98], 25%tile: 6.18 [6.07,6.28], 50%tile: 6.56 [6.44,6.68], 75%tile: 6.86 [6.75,6.97], and 95%tile: 7.58 [7.34,7.83] years, respectively.

CONCLUSIONS: Survival varied significantly by type of multi-valve surgery, worsened with addition of concomitant interventions and improved substantially with increasing annual hospital and surgeon volume. Hospital volume was associated with an improved early hazard for death that abated beyond 3 months post-surgery), while surgeon volume was associated with an improved hazard for death that persisted even beyond the first post-operative year. Consideration should be given to referring multi-valve cases to high-volume hospitals and surgeons.