Objective

The long term effects of off-pump coronary artery bypass grafting (CABG) are the subject of speculation. Critics cite concerns about the number and technical quality of grafts performed. Our institution has over 15 years of experience performing CABG both off-pump (OPCAB) and on cardiopulmonary bypass (CPB). Our null hypothesis was that there would be no difference in a long-term composite of death and revascularisation between the two methods.

Methods

We performed a retrospective cohort study of all isolated CABG at our institution from 2001 - 2015. We used an intention to treat analysis (i.e. conversions classified as OPCAB) and performed univariate analyses of demographic factors to identify confounders. Primary outcome measures were long-term freedom from death and re-intervention. Secondary outcome measures included choice of conduit, number of grafts, training, cardiac enzyme rise, in-hospital mortality & morbidity and hospital stay.

Results

13,220 patients had OPCAB (n=5858, 1.3% converted) or CPB; median follow-up 6.2 years. OPCAB had higher EuroSCORE (5.2±7.2 v 4.7±6.2, p=0.0001), fewer grafts (3.0±0.9 v 3.3±0.9, p<0.0001) but more total arterial grafting (46.1% v 9.4%, p<0.0001). Off-pump CABG also had more trainee 1st operators (15.3% v 12.4%) and lower mortality, cardiac enzyme rise, hospital stay and complications. There was no difference in long-term survival (Log rank p=0.95) or freedom from death and re-intervention (p=0.49).

Conclusion

Off-pump coronary artery bypass grafting is performed with good short and long term outcomes in our institution. Our low conversion rate, despite training, demonstrates that this technique can offer the same longevity as the traditional standard of CABG performed on cardiopulmonary bypass. The number of grafts performed is clinically comparable, if statistically different, and appears to provide equal benefits to survival and freedom from re-intervention as on-pump CABG.