Off-Pump CABG Protects Kidneys Postop but Not Long Term in CORONARY Trial Analysis

June 03, 2014

CHICAGO, IL — Performing coronary artery bypass graft (CABG) surgery off-pump—that is, on the beating heart without cardiopulmonary bypass—led to significantly less postoperative kidney injury compared with standard on-pump CABG, suggests a substudy of a large and influential randomized trial[1]. Importantly, however, the off-pump technique had no apparent effect on renal function one year after surgery.

The findings have "implications for the development, testing, and use of interventions" designed to prevent acute kidney injury similar to what was seen in the trial and underscore that "proof is needed to claim an intervention that reduces the risk of mild kidney injury better preserves long-term kidney function," according to the authors, led by Dr Amit X Garg (Western University, London, ON).

Their report is published in the June 4, 2014 issue of the Journal of the American Medical Association.

In the previously reported primary results of CORONARY , with 4752 patients the largest-ever comparison of the two CABG techniques, there had been no significant difference in the composite end point of death, MI, stroke, or new renal failure requiring dialysis within 30 days.

In the current, prospectively planned substudy of 2932 patients who had been followed for serum creatinine out to one year, the 1472 randomized to the off-pump procedure, compared with the 1460 getting standard CABG, showed a 17% drop (p=0.01) in the relative risk of postoperative acute kidney injury. The end point was defined as a >50% increase in serum creatinine within 30 days.

Adjusted* Relative Risk (95% CI) of Acute Kidney Injury at 30 Days, Off-Pump vs On-Pump CABG, in CORONARY

Definition of Acute Kidney Injury RR (95% CI)
>50% rise in serum creatinine (primary outcome) 0.83 (0.72–0.97)
Death or >50% rise in serum creatinine 0.85 (0.73–0.98)
*Adjusted for age, sex, LVEF, diabetes, long-term use of ACE inhibitors or angiotensin-receptor blockers, statins, diuretics, urgent vs elective CABG, and baseline renal function

But at one year, the rate of loss of kidney function, defined as a >20% loss in estimated glomerular filtration rate (eGFR), was about the same in both groups, at 17.1% for off-pump and 15.3% for on-pump CABG (p=0.23)

When tested using alternative definitions, results for both the short- and long-term end points appeared consistent; results were also similar in the subgroup of patients who had entered the study with chronic kidney disease, the group reported.

Garg discloses receiving grant support from Astellas, Roche, and Pfizer "outside the submitted work." Disclosures for the other authors are listed in the paper.

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