Predictors, causes, and consequences of conversions in robotically enhanced totally endoscopic coronary artery bypass graft surgery

Background: Totally endoscopic coronary artery bypass graft surgery (TECAB), using the da Vinci telemanipulator, has become a reproducible operation at dedicated centers. As in every endoscopic operation, conversion is an important and probably inevitable issue. Methods We performed robotic TECAB in 326 patients (age, 60 years; range, 31 to 90 years); 242 were single-vessel and 84 were multivessel TECAB. Results Forty-six of 326 patients (14%) were converted to a larger incision (minithoracotomy, n = 5; sternotomy, n = 41). Left internal mammary artery injury (n = 7), epicardial injury (n = 4), balloon endoocclusion problems (n = 7), and anastomotic problems (n = 18) were common reasons for conversions. Conversion rate was significantly less for single-vessel versus multivessel TECABs (10% versus 25%; p = 0.001). Nonlearning-curve case (7% versus 21%; p < 0.001) and transthoracic assistance (11% versus 22%; p = 0.018) were associated with lower conversion rates. In multivariate analysis, learning-curve case was the only independent predictor of conversion (p = 0.005). Conversion translated into increased packed red blood cell transfusion in the operating room (3 versus 0 units; p < 0.001), longer ventilation time (14 versus 8 hours; p < 0.001), and intensive care unit stay (45 versus 20 hours; p = 0.001). Hospital mortality was 0.6% in this series, with 1 patient in the conversion group (2.2%) and 1 patient in the nonconverted group (0.4%; not significant). Five-year survival was 98% in nonconverted patients and 88% in converted patients (p = 0.018). There was no difference in freedom from angina or freedom from major adverse cardiac and cerebral events. Conclusions Conversion in TECAB is primarily learning curvedependent and associated with increased morbidity, but does not significantly affect hospital mortality. Both nonconverted and converted patients show good long-term survival, which is comparable to patients undergoing open sternotomy coronary artery bypass grafting. Long-term freedom from angina or freedom from major adverse cardiac and cerebral events is not influenced by conversion.