Risk Factors of On-Pump Conversion during Off-Pump Coronary Artery Bypass Graft

Abstract

Background: Off-pump coronary artery bypass grafting (OPCABG) procedures can avoid the complications of an o n-pump b ypass. However, some c ases u nexpectedly require c onversion to c ardiopulmonary b ypass during OPCABG. The risk factors associated with a sudden need for cardiopulmonary bypass were analyzed. Methods: This retrospective study included 283 subjects scheduled for OPCABG from 2001 to 2010. These were divided into an OPCABG group and an on-pump conversion group. Preoperative, operative, and postoperative variables were compared between the 2 groups. Results: Of the 283 patients scheduled for OPCABG, 47 (16%) were switched to on-pump coronary artery bypass grafting (CABG). The mortality of the both the OPCABG and on-pump conversion groups was not significantly different. The major risk factors for conversion to on-pump CABG were congestive heart failure (CHF) (odds ratio [OR], 3.5; p=0.029), ejection fraction (EF) ＜35% (OR, 4.4; p=0.012), and preoperative beta-blocker (BB) administration (OR, 0.3; p=0.007). The use of intraoperative (p=0.007) and postoperative (p=0.021) inotropics was significantly higher in the conversion group. The amount of postoperative drainage (p＜0.001) and transfusion (p＜0.001) also was significantly higher in the conversion group. There were no significant differences in stroke or cardiovascular complications between the groups over the course of short-term and long-term follow-up. Conclusion: Patients who undergo OPCABG and have CHF or a lower EF (＜35%) are more likely to undergo on-pump conversion, while preoperative BB administration could help prevent conversions from OPCABG to on-pump CABG.

Keywords

• Off-pump coronary artery bypass grafting
• Coronary artery bypass
• Myocardial ischemia
• Hemodynamic instability
• On pump conversion