Learning curve of mitral valve repair: cumulative sum failure analysis from single high-volume center

Background Mitral valve (MV) repair has become the gold standard for treating degenerative mitral regurgitation (MR), yet the success rate of MV repair is still low in clinical practice. While studies focused on the learning process of MV repair are scarce, fully understanding the learning curve could provide valuable information for education and the quality control of MV repair, thus benefiting patients. This observational study aimed to evaluate the learning process and performances of individual surgeon for MV repair for degenerative mitral disease using data from a single high-volume center. Methods Profiles of patients who underwent MV repair for degenerative MR at our institution from January 2003 to December 2016 were analyzed retrospectively. Overall and individual learning curves for the repair rate and major adverse events were calculated using sequential probability cumulative sum failure analysis. Average learning curves for major adverse events and operative time were also analyzed, by calculating the average incidence of adverse events and operative time of all operations stratified by accumulated operation numbers of individual surgeon. Altogether, we evaluated 2,482 operations performed by 14 surgeons. Results There was an obvious learning curve for the repair rate at the institution and individual surgeon levels. Altogether, 50 to 200 operations were needed to overcome the repair rate learning curve, yet wide variation was observed among individual surgeons. The learning process for individual surgeons became faster after the turning point in the institutional learning curve appeared. No obvious learning curve was observed at the institution or individual level for major adverse events and in-hospital mortality. Conclusions The number of cases required to overcome the learning curve for repair rate is substantial, although there is marked variation among surgeons. Individuals' learning curves accelerate as the institution accumulates experience. MV repair is safe in experienced high-volume center. Close monitoring is necessary when surgeons begin to practice new techniques.