Comparing Blood Loss, RBC Transfusions and Inflammatory Marker Changes Among Methods of CPB

• To compare blood loss and PRBC transfusions for MECC, OPCAB, and conventional CPB in patients undergoing primary CABG surgery. [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  

• To assess survival and readmission rates 30 days post discharge. [ Time Frame: 1 year ] [ Designated as safety issue: No ]
  Description: Through interview and medical record review subjects will be assessed 30 days post discharge for readmissions, adverse events and survival
  
  
• To assess and compare levels of tissue inflammation using biomarkers. [ Time Frame: 1 year ] [ Designated as safety issue: No ]
  Blood samples collected at five timepoints preop, intraop and postoperatively will be evaluated for C-Reactive Protein, C5 Complement Activation and IL-6 levels and compared among the 3 groups.
  
  
• To assess and compare levels of tissue inflammation using genomic mapping. [ Time Frame: 1 year ] [ Designated as safety issue: No ]
  Compare blood levels of inflammation by completeing genomic mapping using micrarray technology
  
  
• To identify a definition of a genomic signature of inflammation that predicts best outcomes in using CECC, MECC, and off-pump for CABG surgery. [ Time Frame: 1 year ] [ Designated as safety issue: No ]
  
• To use results of the trial to develop a a future large scale trial. [ Time Frame: 2 years ] [ Designated as safety issue: No ]
  

Off-pump coronary artery bypass grafting (OPCAB) and the use of minimal extracorporeal circulation system (MECC) have both been proposed as alternatives to avoid the harmful effects of conventional cardiopulmonary bypass (CPB). However, with the technically more demanding nature of off-pump CABG, the potential short-term benefits of off-pump surgery may not translate into long-term benefits in providing optimal revascularization. In this prospective cohort study, it is our goal to evaluate short term outcomes as demonstrated by blood loss, transfusion need, and systemic inflammatory response during CABG surgery using MECC or conventional CPB or OPCAB.

In addition to the technical challenges posed during off-pump CABG surgery, it is also known that a significant systemic inflammatory response is mounted in patients who undergo conventional CPB. This inflammatory response is a combined effect of 1) the placement of required tubes and lines for connection with the heart/lung machine, 2) hemodilution, and 3) hypothermia. In this study, we will measure levels of tissue inflammation through the use of specialized laboratory tests (C Reactive Protein, C5 complement activation and Interleukin 6), and we will correlate these inflammation levels to the three different cardiopulmonary bypass options. It is our hypothesis that MECC will provide the stable operating environment of conventional CPB and the patient benefits of less blood loss, decreased transfusion rate, and decreased inflammation levels seen in patients with OPCAB.

Statistical Analysis: Multivariable regression models will be used to investigate the association of the MECC pump, conventional CPB versus off-pump with the outcomes controlling for risk factors recognized by the STS associated with post-CABG adverse outcomes) and other clinical and non-clinical factors. The association of each outcome of interest with MECC versus conventional CPB and MECC versus off-pump will be estimated with 95% confidence intervals (CIs). With a cohort of 102 patients (34 in each of three study groups) we will have over 80% power to detect a 71% relative reduction (30% absolute difference) in transfusion rate among CABG patients using a MECC pump as compared to conventional pump patients assuming that 42% of patients undergoing CABG with conventional pump require a transfusion