Conversion to cardiopulmonary bypass in off-pump coronary artery bypass grafting: Its effect on outcome

The surgical outcome of patients requiring conversion to cardiopulmonary by pass (CPB) during myocardial revascularization using the less invasive surg ical approach (LISA) was assessed. The LISA was recently introduced as a te chnique for complete myocardial revascularization without CPB. It combines avoidance of CPB with the versatility of a median sternotomy for access to all coronary vessels. We have previously demonstrated reduced risk-adjusted mortality and complications in off-CPB coronary artery bypass grafting (CA BG) using LISA compared to standard myocardial revascularization. From Janu ary to December 1997, 1210 patients underwent isolated CABG at our institut ion. Of these patients, 832 (63%) were scheduled as on CPB cases and 378 (3 7%) as off-CPB. Of the off-CPB patients, 48 were converted to CPB. Team A s urgeons used LISA as their primary strategy for CABG whereas team B surgeon s used off-CPB CABG in selected patients. Conversions were divided in three classes: Class I patients were converted when the surgeon considered compl ete revascularization impossible off-CPB; Class II patients were converted due to hemodynamic instability during the procedure; and Class III patients were converted due to graft malfunction, determined by flow measurements o r clinical evidence. There were four deaths. AII had perioperative infarcti ons and required intra-aortic balloon pump (IABP). Conversion to CPB occurr ed in up to 25% of patients scheduled for off-CPB CABG. When off-CPB cases are done using the comprehensive LISA technique and modern technology, conv ersion rates may be reduced to 11%. Conversion is in general well tolerated except when it is instituted for graft malfunction combined with hemodynam ic instability or collapse.