Should off-pump CABG be abandoned?

We went back to the STS database and we looked at whether this applies only at some centers or all centers, some surgeons or all surgeons. We looked at almost a million cases, 210,469 of which were at sites that had a large off-pump CABG volume. With the usual adjustments, off-pump CABG was associated with significant reduction of risk of death, stroke, renal failure, any morbidity or mortality or prolonged length of stay, compared with on-pump bypass. This benefit was even more pronounced after adjustment for surgeon effect. Once again, the greater reduction was enjoyed by those patients who had the highest preoperative risk. In all predicted risk quartiles, off pump bypass reduced risk of death and stroke and that magnitude increased with increasing predicted risk of mortality. This was seen in large-volume centers and low-volume centers.

Similar results were seen in a recent multicenter, randomized, prospective trial by Lemma et al. that assigned 411 patients to either off- or on-pump coronary bypass (J. Thorac. Cardiovasc. Surg. 2012;143:625-31). There was reduced early mortality and morbidity among higher-risk patients. Interestingly, in this study, they used an experience-based randomization scheme, in which they had surgeons within each center who like to do off-pump CABG and those who like to do on-pump CABG, and each surgeon had hundreds of cases under his belt. For the primary endpoint, a composite of death, MI, stroke or TIA, renal failure, acute respiratory distress syndrome, or reoperation for bleeding, the rates were 5.8% of off-pump and 13.3% for on-pump patients (odds ratio, 2.5; P = .01).

I think the conclusions are clear, but not everyone has reached these same conclusions. In ROOBY, the results were different. Although the study was well conducted, it enrolled low-risk patients, in whom avoidance of CPB was unlikely to improve the expected excellent outcomes. And the operations were performed by residents, with supervising attendings who themselves only had to do 20 total career off-pump cases to be eligible. I think this lack of experience is well demonstrated by the 12.5% conversion rate from off-pump cases to on-pump in that trial. ROOBY enrolled the wrong patients and used the wrong surgeons.

In the CORONARY trial, conducted by Dr. Lamy in Canada but enrolling patients from 19 countries outside of Canada, there was no difference in the primary endpoint of death, stroke, MI, and renal failure at 30 days, but there was a decrease in transfusion, reoperation for bleeding, acute kidney injury, or respiratory complications. There wasn\'t a difference in stroke, interestingly, but the surgeons in this trial appropriately converted a hundred patients from on pump to off pump to avoid manipulating a calcified aorta. This was a good, well-conducted trial.

However, the primary outcome in CORONARY differed when assessed according to EuroSCORE. When the EuroSCORE was low, on pump outperformed off pump. When the EuroSCORE was high, off pump outperformed on pump.

These two trials offer important perspective: the ROOBY trial, enrolling low-risk patients, was actually in favor of on-pump CABG. The CORONARY trial, enrolling higher-risk patients, had a slight benefit in favor of off-pump CABG, and this was particularly evident in the Canadian cohort of 830 randomized patients, in which the primary outcome was, in fact, statistically significantly better in the off-pump group at 9.2% vs. 13.7%.

At the end of the day, I think it matters in whom you do off-pump CABG and how well you do it. It may not be for every patient or for every surgeon; off-pump CABG requires a focused and sustained effort to master a new set of physical and psychological skills to accomplish precise and complete revascularization. When we can do this, I think, we offer better outcomes for our patients.

Dr. John Puskas is the chairman of the department of cardiac surgery at Mount Sinai Beth Israel in New York. Dr. Puskas disclosed that he also does both on- and off-pump CABG. He received royalties from coronary surgical instruments marketed by Scanlan, as well.

References

JAMA 2004;291:1841-9

Ann. Thorac. Surg. 2009;88:1142-7

N. Engl. J. Med. 2009;361:1827-37

N. Engl. J. Med. 2010;362:851

N. Engl. J. Med. 2012;366:1489-97

N. Engl. J. Med. 2013;368:1179-88

Ann. Thorac. Surg. 2011;91:1836-42

J. Thorac. Cardiovasc. Surg. 2012;143:625-31