Does the Number of Grafts Influence Surgeon Choice and Patient Benefit of Off-Pump Over Conventional On-Pump Coronary Artery Revascularization in Multivessel Coronary Artery Disease?

Background It is not known whether surgeons preferentially assign patients requiring fewer grafts (1 to 3) to off-pump coronary artery bypass graft surgery (OPCABG) and those requiring many grafts (4 to 7) to conventional on-pump coronary artery bypass graft surgery (ONCABG), nor whether risk-adjusted outcomes are similar for OPCABG and ONCABG among patients receiving 1 to 3 and 4 to 7 grafts. Methods Emory Hospitals’ prospective database was retrospectively reviewed for 11,413 consecutive, isolated, primary coronary revascularization procedures between January 1997 and May 2005. Patients were divided into four groups: OPCABG 1 to 3 grafts (n = 3,187), OPCABG 4 to 7 grafts (n = 1,305), ONCABG 1 to 3 grafts (n = 3,279), and ONCABG 4 to 7 grafts (n = 3,642). A propensity score for surgery type was estimated from 39 risk factors. Multivariable logistic regression examined independent impact of surgery type and number of vessels grafted on outcomes. Computed interactions determined whether the effect of surgery type on risk-adjusted outcomes was consistent across groups. Results Patients requiring 4 to 7 grafts had adjusted odds of receiving ONCABG 2.92 times higher than patients requiring 1 to 3 grafts (p < 0.001). The OPCABG patients had adjusted odds ratios of 0.53 for death (p = 0.007), 0.42 for stroke (p < 0.001), 0.51 for major adverse cardiac events (p < 0.001), and 0.71 for renal failure (p = 0.05) as compared with ONCABG patients. The interaction between OPCABG and number of vessels grafted was not statistically significant. Conclusions This study demonstrates that surgeons tend to perform OPCABG for patients requiring 1 to 3 grafts and ONCABG for those requiring 4 to 7 grafts. Off-pump CABG is associated with reduced adjusted risk of adverse outcomes compared with ONCABG. This benefit is consistent for patients requiring 1 to 3 or 4 to 7 grafts.