Learning Curve of Totally Endoscopic Non Rib-spreading Mitral Valve Surgery

Objective: Minimally invasive mitral valve surgery has been shown to be transferable through proctoring and careful analysis of surgeons’ performance. Totally endoscopic mitral valve sur- gery without rib spreading represents an advancement in the mitral surgery field. As invasiveness decreases, technical demand increases and careful proctoring and monitoring is required. We use the CUSUM analysis to elucidate the performance and the learning curve of our group switching from standard minimally invasive mitral valve surgery to totally endoscopic approach. Methods: From July 2015 to April 2018, 177 patents under- went totally endoscopic mitral valve surgery. The procedure was adopted for “all-comers” patients with either isolated mitral and/or tricuspid valve disease. Euroscore II was used to the risk against which the surgical failure was compared to construct the CUSUM curve. Surgical failure was defned as: 1) perioperative death; 2)intraoperative conversion to sternot- omy; 3) perioperative myocardial infarction (new Q- waves >0.04 ms and/or reduction in R-waves >25% in at least two contiguous leads on electrocardiogram); 4) perioperative aortc dissection; 5) stroke (defined as Rankin Modified scale score >= 6) in-hospital reoperation for any cause. Also we consid- ered surgical procedure end-points of failure as the occur- rence of one or more of the following: 1) cardiopulmonary bypass (CPB) time exceeding 95% of our “conventional MIMVS” CPB tme; 2) cross-clamp (X-clamp) time exceeding 95% of our conventional approach; 3) preparation time exceeding 95% of our current MIMVS setup. Results: Procedure specific risk adjusted probability of failure, probability of failure during preparation time, prolonged CPB time and prolonged cross clamp time were always in control. Conclusions: Between 50 and 60 procedures are required to reach the lower boundary to overcome procedure-specific risks, manage the surgical setup and be proficient in the new way of mitral repair as reflected by the cardiopulmonary bypass time and cross-clamping time.