A Comparison of Acute Renal Dysfunction Following on-Pump Versus off-Pump CABG

Background: Coronary artery by-pass surgery (CABG) has traditionally been performed with the use of cardiopulmonary by-pass (on-pump CABG), with cardioplegic arrest. In the mid-90s surgeons began to perform the procedure on a beating heart, without the by-pass. This was an attempt to reduce a number of complications related to the cardiopulmonary bypass machine used for extracorporeal circulation during on-pump CABG. Aim: To compare acute renal dysfunction after first isolated Off-pump versus On-pump coronary artery by-pass graft surgery (CABG) and to determine if there is a difference between the two groups. Methodology: The study was carried out at the Heart Institute, Medanta Hospital, New Delhi India. The patients were randomized to undergo on-pump or off-pump coronary by-pass surgery and were prospectively followed. Preoperative and post-operative (24 hours, 48 hours and one week) serum creatinine and urea were recorded. Patients with preoperative serum creatinine greater than 1mg/dl and urea greater than 20mg/dl, as well as those having combined CABG and valve surgery were excluded. Results: A total number of 288 patients had CABG surgery (154 had Off-pump CABG while 134 had On-pump CABG). Eighty seven percent were male while 12% were female. There was a rise in creatinine from the preoperative mean baseline for both groups. The average rise of preoperative creatinine for on-pump was 0.4mg/dl compared to 0.01mg/dl for off-pump and this was statistically significant. The serum creatinine however, dropped to 0.84mg/dl for the on-pump and 0.73mg/dl for the off-pump groups by one week. The urea level for both groups also rose steadily for the one-week period. This elevation in serum urea was, however, statistically significant for the on-pump group. Conclusion: This study has shown that on-pump CABG causes significant acute renal dysfunction compared to off-pump coronary artery bypass surgery.