Reduced post-op kidney injury seen in off-pump CABG patients

But no evidence found for better preserved long-term kidney function 1 year post-op

PATIENTS who underwent coronary artery bypass graft (CABG) surgery and were off pump (not put on a heart-lung machine) showed a reduced risk of postoperative kidney injury compared to patients who were on-pump, according to a study published in the Journal of the American Medical Association.

However, it also found that there was no evidence of better preserved kidney function one year after the surgery.

“The finding emphasized proof is needed to claim an intervention that reduces the risk of mild acute kidney injury better preserves long-term kidney function for the group that received it,” the authors led by Dr. Amit Grag, Ph.D. of Western University, London, Ontario wrote.

They studied a sample size of 2,932 patients from 63 sites in 16 countries. It was a sub-study of the landmark CORONARY (Coronary Artery Bypass Grafting Surgery Off- or On-pump Revascularization Study), which enrolled CABG patients who were randomized to receive off-pump or on-pump procedure.

Close to 30 percent of the patients developed mild or moderate acute kidney injury, which is defined as a =50 percent increase in serum creatinine level, after cardiac surgery.

Background studies have stated that an intervention that reduces the risk of acute kidney injury better preserves longer-term kidney function has not been proven and that the effects of mild or moderate acute kidney injury in the long-term kidney function are not clear.

“This has implications for the development, testing, and use of interventions designed solely to prevent the degrees of acute kidney injury observed in CORONARY, and in determining acceptable adverse effects and costs of such interventions,” said the authors.

Less acute kidney injury was found off-pump at 17.5 percent compared to on-pump at 20.8 percent CABG surgery within 30 days. It was defined that within 30 days of the surgery, 50 percent or greater increase in serum creatinine concentration was found from pre-operative baseline concentration. Meanwhile, loss of kidney function after one year meant 20 percent or greater loss in estimated glomerular filtration rate from baseline.

There was no significant difference between the two groups in the loss of kidney function at one year – 17.1 percent for off-pump and 15.3 percent for on-pump.

Absolute risk reduction of acute kidney injury in off-pump compared to on-pump CABG surgery in the subgroup analysis was greater in those with chronic kidney disease than those without chronic kidney disease. With JAMA report

VitalSigns Issue 64 Vol. 3, June 1-30, 2014