Learning the Learning Curve of Robotic Coronary Artery Bypass

Abstract

Title: Learning the Learning Curve of Robotic Coronary Artery BypassAuthors : Saqib Masroor, MD, MBA1, Abdullah Nasif, MD1 1Division of Cardiothoracic Surgery, Department of Surgery, University of Toledo Medical Center Toledo, OH USAManuscript: The Learning Curve of Robotic Coronary Arterial Bypass Surgery: A Report from The STS DatabaseDisclosure : NoneWord Count : 1229Learning the learning curve of robotically assisted coronary artery bypass grafting is important for the advancement of this technique and the improvement in patient outcomes. There have been many reports of single surgeon learning curves.1, 2 But one can argue that they depict one surgeon’s journey, depicting his or her dedication to the field and making generalization to other surgeons difficult, if not impossible.In this issue of the Journal of Cardiac Surgery, Patrick et al, report on their investigation of the Society of Thoracic Surgeons (STS) database for Robotically Assisted Coronary Artery Bypass (RA-CABG) procedures and the beginner surgeon’s learning curve.3Between 2014 and 2018, a total of 1195 RA-CABGs were performed by 114 surgeons, with 74 surgeons performing <5 procedures and only 9 surgeons performing >25 procedures. The median number of cases performed was 2. The patient population was younger and relatively lower risk. The cases included single-vessel as well as multi-vessel Minimally Invasive Direct Coronary Artery Bypass (MIDCAB) in addition to Totally Endoscopic Coronary Artery Bypass (TECAB) and there is no subgroup analysis reported for the different procedures. The authors conclude that the learning curve for procedural success is overcome by the 10th case, even though the curve for reoperation is still steep by the 25th case. Operative mortality however was similar in the two groups. The authors conclude that surgeon experience is an independent predictor of RA-CABG procedural success and that the learning curve consistently flattens after the surgeon’s 10th case. We agree with the first but not the second conclusion. Here is why!In 2013, Prof Mohr’s group in Leipzig reported on the learning curve of minimally invasive mitral valve surgery at their institution over a 17-year period involving 3895 operations performed by 17 surgeons performing their first minimally invasive procedure, using the sequential probability cumulative sum (CUSUM) statistical technique.4 Learning curves were then determined for total operation times, aortic cross-clamp times, and primary outcomes. The mean number of operations per surgeon was 189. The authors reported a learning curve of between 75-125 procedures, with evidence that surgeons needed to perform more than 1 cases per week to maintain good results. Importantly however, patient mortality was not compromised because of the learning curve.To assess the learning curve involved in performing a task, it is important that both the task and the tools needed for the task remain constant. The above publication fulfills both of these criteria. 82 percent of cases were mitral valve repair and 18 percent were mitral valve replacement. The surgical technique and technology used was nearly identical and robotic mitral valve procedures were excluded. The institution had the same leadership over the period, allowing for a very stable work environment as well as a consistent approach including case selection, operative technique etc. As much as possible, every variable was the same, except the variable under investigation-‘the beginner surgeon’. The same group had reported the learning curve for MIDCAB to be between 50-100 cases for 8 surgeons at their institution.5Now let us analyze the report from Patrick et al.3 In this report, the task is not the same and neither are the tools. Single vessel RA-MIDCAB is a less challenging procedure than multi-vessel RA-MIDCAB, with its associated variety of conduit procedures (such as bilateral Internal Mammary Artery (IMA) grafting, Radial Artery T-grafting from Left Internal