Conversion to on pump from OPCAB is associated with increased mortality: Results from a randomized controlled trial

Objective: Recent developments in cardiac stabilization devices, have made OPCAB feasible. However, there is conflicting evidence to date regarding the rate and adverse events associated with conversion from OPCAB to CABG with CPB. The objective of the present study was to review all conversions in the setting of a randomized controlled trial comparing CABG with or without CPB. Methods: Three hundred patients requiring CABG surgery at a single institution were prospectively randomized to have the procedure performed with CPB (n=150) or OPCAB (n=150). Patients that could not be performed OPCAB were defined as conversion group (cross over). Results:Twenty patients were converted from OPCAB to CABG with CPB because of hemodynamic instability (14/20), small target vessel (5/20), or inadequate visualization (1/20). Seventeen were converted during attempts at coronary anastomosis: LAD/diagonal (7/20), circumflex (8/20), or right coronary (2/20). The overall in hospital mortality rate for the trial was 1% but was significantly higher in converted patients (10 vs. 0%; P=0.01). Converted patients required significantly more inotropes (P=0.001) and blood transfusions (P=0.05). An elevated BMI was the only pre-operative variable that appeared to be associated with conversion. Conclusions: In the setting of a randomized controlled trial the overall conversion rate associated with OPCAB reached 13% and was associated with an increased risk of mortality.