CABG: On vs. Off Pump

A recent article in the New England Journal of Medicine (2004:350; 21-8) and subsequent newspaper articles have raised questions about the durability of Off-Pump Coronary Artery Bypass surgery. We have been  proponents of the beating heart technique for the past several years and now use it in more than 95% of our CABG patients. It is our firm conviction that by avoiding use of the heart-lung machine, our patients experience less perioperative morbidity than those who undergo a traditional CABG using the heart-lung machine. This belief was recently confirmed by the Society of Thoracic Surgeons analysis of our data for isolated CABG procedures showing a lower mortality (1.2%), stroke (0.6%), renal failure (1.76%), infection rate (0.0%), or length of stay (4 days) than other programs nationally.

The NEJM article was a randomized comparison of 104 patients to on-pump vs. off-pump CABG over a two-year period.  Postoperative coronary angiograms were performed at three months to assess graft patency. In the first 72 hours after surgery, on-pump patients exhibited a greater release of Troponin T compared to on-pump patients. At three months 98% of on-pump grafts were patent as compared with 88% of the off-pump group. This discrepancy has raised concerns about the role of the off-pump technique and its efficacy.

We believe the NEJM article is flawed for several reasons. The surgeons were new to the technique (two years) and used it in only a very small fraction of their practice (13%). Lack of familiarity with the technique may have contributed to their results. Intraoperative anticoagulation regimens were different for each patient group, radial artery grafts were used 50% more often in the off –pump group, and approximately 22% of patients were not restudied. These discrepancies may have significantly contributed to their findings.

Several previous studies have clearly documented the beneficial effects of off-pump techniques in experienced hands. Larger series have shown lower rates of operative mortality, stroke, and freedom from any postoperative complication with the use of the off-pump technique.  On-pump surgery was associated with more encephalopathy, sternal wound infection, red blood cell usage, and renal failure requiring dialysis, and length of stay. Graft patency rates were not significantly different and the cost of off-pump surgery was 14% less.

Therefore, we remain committed to providing the best possible outcomes for our patients using whatever technique achieves that goal. Review of our outcome data validates our decision to embrace the off-pump methods as an important means to achieve that end.