Meta-Analysis: Off-Pump Approach Increases Mortality Risk in CABG

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Although performing coronary artery bypass graft (CABG) surgery off pump—with the heart still beating—has been touted as a way to reduce complications, a new meta-analysis published online March 14, 2012, in the Cochrane Database of Systematic Reviews finds that the approach raises the likelihood of death.

Christian H. Møller, MD, of Copenhagen University Hospital (Copenhagen, Denmark), and colleagues identified 86 randomized clinical trials that enrolled patients (n = 10,716) undergoing first-time isolated CABG for ischemic heart disease.

In a pooled analysis, off-pump CABG increased the overall risk of all-cause death, but the difference was even more pronounced when the researchers included only the 10 trials (n = 4,950) thought to be of high methodological quality (table 1).

Table 1. All-Cause Mortality: Off- vs. On-Pump CABG




RR (95% CI)

P Value




1.24 (1.01-1.53)


Trials with Low Risk of Bias



1.35 (1.07-1.70)


However, performing surgery off pump did not influence the likelihood of adverse events including MI, stroke, renal insufficiency, or repeat revascularization.

In terms of other complications, off-pump CABG was associated with a reduction in distal anastomoses (mean difference -0.28; 95% CI -0.40 to -0.16), which may indicate incomplete revascularization, but the paper notes that heterogeneity was “very high” among the trials. And while the off-pump technique appeared to reduce post-operative atrial fibrillation, this effect was no longer significant when only trials with low risk of bias were analyzed.

“Our data raise a warning regarding coronary artery bypass surgery on the beating heart,” Dr. Møller and colleagues conclude. Moreover, they add, the findings suggest that funding sources matter, with device industry-funded trials less apt to show harm from off-pump CABG.

“Based on the current evidence, on-pump CABG should continue to be the standard surgical treatment,” the researchers advise.

On-Pump Better but Not for Everyone

Dr. Møller, who estimated that less than 20% of CABG surgeries are now conducted off-pump, told TCTMD that the results were unexpected. “Actually, we [were a little surprised when we found] that off-pump CABG increased mortality, as we, like many others, had expected that off-pump CABG would have been superior to on-pump CABG,” he related in an e-mail communication.

Though on-pump is preferred, “[o]ff-pump CABG should still be considered in patients with severely calcified aorta where cannulation and cross clamping the aorta is too risky. Patients with 1-vessel disease [who only require] revascularization of the left anterior descending coronary artery (ie, LIMA to LAD) may also be candidates,” Dr. Møller said, adding that more trials are needed in these populations.

The CORONARY study, which is evaluating on- vs. off-pump CABG in nearly 5,000 patients, will be presented next Monday, March 26, at the American College of Cardiology Annual Scientific Session/i2 Summit in Chicago, IL. Long-term outcomes from the trial will be of particular importance, Dr. Møller emphasized.


Møller CH, Penninga L, Wetterslev J, et al. Off-pump versus on-pump coronary artery bypass grafting for ischaemic heart disease. Cochrane Database of Systematic Reviews. 2012;3:CD007224.



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  • The study was funded by the Aase and Ejnar Danielsens Foundation Center for Clinical Intervention Research, the Copenhagen Hospital Corporation’s Medical Research Council, the Danish Heart Foundation, the Danish Medical Research Council, and the Rigshospitalet Research Council.
  • Dr. Møller reports being involved in the Best Bypass Surgery trial, which was included in the review.