Off-pump CABG shows short- but not long-term kidney benefits

Patients who underwent off-pump CABG surgery were less likely than on-pump patients to experience postoperative acute kidney injury, based on an analysis of CORONARY data published in the June 4 issue of JAMA. But kidney function remained similar between the groups at one year.

The randomized controlled clinical trial CORONARY (Coronary Artery Bypass Grafting Surgery Off- or On-pump Revascularisation Study) had found no differences in outcomes between the two techniques in patients undergoing their first isolated CABG. The substudy led by Amit X. Garg, MD, PhD, of London Health Sciences Center, enrolled 2,932 CORONARY participants between January 2010 and November 2011 to assess kidney function based on additional serum creatinine measurements.

One primary endpoint was postoperative acute kidney injury, which they defined as a 50 percent or greater increase in serum creatinine within 30 days compared with preoperative measurements. The other primary endpoint was loss of kidney function at one year, which was set at 20 percent or greater loss of estimated glomerular filtration rate (GFR) compared with preoperative measurements.

At one year, 90 percent of patients in the substudy had a recorded serum creatinine value. The rate of acute kidney injury was lower in the off-pump compared with the on-pump group, at 17.5 percent vs. 20.8 percent. At one year, there was no significant difference between the groups for GFR (17.1 percent for off-pump vs. 15.3 percent for on-pump).

The relative reduced risk of postoperative acute kidney injury was 17 percent with off-pump CABG. “[C]onvincing evidence now exists that off-pump CABG surgery reduces the risk of mild to moderate acute kidney injury,” Garg et al wrote. “The relative and absolute risk reduction appears greatest in patients with preoperative chronic kidney disease.”

Still, the results didn’t show any advantage over the longer term. The researchers speculated that follow-up may have been too short, the serum creatinine readings may have been flawed or the degree of injury reduction was too small and in too few patients to show a long-term effect.