Mastering the Learning Curve for Robotic-Assisted Coronary Artery Bypass Surgery

Previous studies have evaluated the learning curve to achieve competency in robotic-assisted coronary artery bypass grafting (CABG) but have not identified thresholds for mastery. Robotic-assisted CABG is a minimally invasive alternative to sternotomy CABG. The purpose of this study was to evaluate the short- and long-term outcomes of this procedure and to estimate the threshold for achieving mastery.

From 2009 to 2020, 1000 robotic-assisted CABG procedures were performed at a single institution. Robotic left internal mammary artery (LIMA) harvest followed by off-pump, LIMA-left anterior descending artery grafting using a 4-cm thoracotomy was performed. Short-term outcomes were obtained from The Society of Thoracic Surgeons database, and long-term follow-up was obtained by telephone questionnaires from dedicated research nurses for all patients more than 1 year from surgery.

Mean patient age was 64 ± 11 years, Society of Thoracic Surgeons predicted risk of mortality was 1.1% ± 1.5%, and 76% (758) of patients were men. Thirty-day mortality occurred in 6 patients (0.6%; observed-to-expected ratio, 0.53), 5 patients (0.5%) experienced a postoperative stroke, and postoperative LIMA patency was 97.2% (491/505). Mean procedure time decreased from 195 minutes to 176 minutes, and conversion to sternotomy decreased from 4.4% (22/500) to 1.6% (8/500) after 500 cases. Short-term outcomes suggested expertise was reached between 250 and 500 cases. Long-term follow-up was completed in 97% of patients (873/896) with a median follow-up of 3.9 years (interquartile range, 1.8-5.8), and the overall survival rate was 89% (777).

Robotic-assisted CABG can be performed safely with excellent results even during a surgeon's early experience. However the learning curve to achieve mastery is longer than required to achieve competency, with a threshold of approximately 250 to 500 cases.