Long-term Off-Pump CABG Results Deflate in Large, Real-world Study

As time goes by, patients treated with off-pump CABG surgery have higher mortality, less complete revascularization, and more need for repeat revascularization in the ensuing years than those treated with an on-pump approach, new real-world data suggest.

“On-pump surgery makes it easier for a surgeon to deliver a technically perfect result, and that translates to superior long-term outcomes for our patients,” said Joanna Chikwe, MD (Icahn School of Medicine at Mount Sinai, New York, NY), lead author of the new paper. “Both techniques have great short-term results, that is not in any doubt, but for maximum long-term benefit it seems that on-pump surgery is the route to take.”

The findings are similar to those of the recent ROOBY-FS trial, which found that among patients treated in Veterans Administration hospitals, mortality and MACE were both higher at 5 years with off-pump surgery. The trial has been criticized for having a predominantly male population and for allowing large numbers of inexperienced residents to perform procedures.

Both techniques have great short-term results, that is not in any doubt, but for maximum long-term benefit it seems that on-pump surgery is the route to take. Joanna Chikwe

The new study involved registry data from a single state from 2005 to 2011. According to Chikwe, the study is a “snapshot of what’s going on in contemporary practice,” adding that they purposely included highly experienced surgeons who had performed over 900 cases using either approach and worked in a wide variety of practice settings.

“I think we’ve convincingly shown that experience is not the issue here,” Chikwe told TCTMD. “It’s simply that for most surgeons and most patients it’s technically more difficult to achieve a complete revascularization with off-pump surgery.”

ROOBY-FS senior author Frederick Grover, MD (University of Colorado Denver), told TCTMD in an interview that the new study strengthens the ROOBY-FS findings and extends them to an even broader and larger group of patients treated by highly experienced surgeons.

“We don’t have our 10-year data crunched yet, but we will in the next year,” he said. “and it will be interesting to see what we find.”

In an accompanying editorial, Faisal G. Bakaeen, MD (Cleveland Clinic Heart and Vascular Institute, OH) and Vinod H. Thourani, MD (MedStar Heart and Vascular Institute, Washington, DC), say the findings “will undoubtedly be challenged by the ever-diminishing modern-day off-pump enthusiasts” on the basis of inherent biases that cannot be fully adjusted for in administrative databases.

“Regardless, this paper affirms prevailing evidence that, at a population level, on-pump should be the default strategy for CABG,” Bakaeen and Thourani assert.

Incomplete Revascularization Predicts Late Mortality

For the study, published online ahead of the September 25, 2018, issue of the Journal of the American College of Cardiology, Chikwe and colleagues analyzed long-term outcomes for patients who underwent CABG (6,950 off-pump and 15,295 on-pump) included in mandatory clinical and administrative registries from the New Jersey Department of Health.

At 10 years, mortality was 33.4% in the off-pump group vs 29.6% in the on-pump group (adjusted HR 1.11; 95% CI 1.04-1.18). Incomplete revascularization was nearly twice as high in the off-pump group (15.7% vs 8.8%; P < 0.001), with more off-pump patients requiring repeat revascularization (15.4% vs. 14.0%; P = 0.048). Compared with patients who had complete revascularization, those who did not had higher late mortality (HR 1.15; 95% CI 1.06-1.23). Rates of MI, stroke, and new dialysis, however, were similar in the two groups.

The researchers also tried to account for surgeon preference and experience with off-pump procedures in their analysis, but found that even patients treated by high-volume surgeons with a 90% or greater preference for off-pump surgery still had greater long-term mortality than those undergoing on-pump surgery (HR 1.36; P = 0.025).

“In this pool of relatively expert surgeons, off-pump CABG was still associated with fewer anastomoses and greater likelihood of incomplete revascularization, which we found to be an independent risk factor for late mortality in all patients,” Chikwe and colleagues write.

To TCTMD, Grover said he agreed with that conclusion.

“Incomplete revascularization is a factor that would affect long-term results,” he said. “Although this issue [of off-pump vs on-pump] is less controversial than it once was, it’s important to report these results so that we have consistency.”

The Changing Face of CABG Practice

According to Bakaeen and Thourani, surgeons are paying attention to the contemporary data, with recent numbers from the Society of Thoracic Surgeons Adult Cardiac Surgery Database suggesting that off-pump CABG had declined by 17% since its peak in 2002.

Although this issue [of off-pump vs on-pump] is less controversial than it once was, it’s important to report these results so that we have consistency. Frederick Grover

“A third of all American surgeons perform no off-pump operations, and the vast majority (86%) perform < 20 per year,” they write. “This decrease in off-pump CABG is likely due to its increased technical difficulty, as well as lack of benefit in most patients.” While it is “best performed by a few select surgeons experienced in this technique,” they add that it “should be part of the armamentarium of all cardiac surgeons to optimize outcomes when faced with anatomic or physiological scenarios wherein avoiding cardiopulmonary bypass or aortic manipulation is advantageous.”

Grover said while some surgeons are probably not going to change their minds about the value of off-pump on a routine basis, he was struck by a session he attended last year at the American Association for Thoracic Surgery (AATS) meeting in which a moderator asked how many in the audience still perform off-pump.

“I looked around to see how many hands went up and I would say it was less than 10%,” Grover noted. “That being said, there are surgeons who have devoted much of their career to developing and fine-tuning their [off-pump] technique and they may well be getting very good results.”