Outcomes of Mitral Valve Repair Among High- and Low-Volume Surgeons Within a High-Volume Institution

Background: Volume-outcome relationships have been described for mitral valve repair at the institution and surgeon level. We aimed to assess whether this relationship is mitigated at high-volume (HV) mitral repair centers between HV and low-volume (LV) surgeons. Methods: All mitral repair cases at an HV mitral center (mean, 192 annual repairs) from 1992 to 2018 were considered. Cases with concomitant procedures other than tricuspid and atrial fibrillation procedures were excluded. Surgeons who performed ≥25 repairs per year were considered HV. The primary outcome was operative mortality; secondary outcomes were operative complications, long-term mortality, and reoperation. Results: In total, 2653 mitral repairs from 19 surgeons were included. The mean age of the patients in the HV and LV groups was 59.6 years and 61.8 years, respectively (P = .005), with no difference in other baseline characteristics. HV surgeons had significantly shorter median aortic cross-clamp times (80 vs 87 minutes; P < .001) compared with LV surgeons; however, there was no significant difference in operative mortality (0.9% vs 1.6%; P = .19), reoperation, perioperative complications, or length of stay. LV surgeons had higher repair conversion to replacement than HV surgeons did (9.0% vs 3.4%; P < .001). In the risk-adjusted analyses, surgeon volume group did not have an impact on longitudinal survival or reoperation. Conclusions: At an HV mitral repair institution, LV surgeons appear to have short- and long-term outcomes similar to those of HV surgeons despite increased conversion rates. These findings suggest that institutional volume may mitigate the surgeon volume outcome. However, complex repairs may benefit from referral to HV surgeons, given the lower conversion rate.