Effects of delayed remote ischemic preconditioning on peri-operative myocardial injury in patients undergoing cardiac surgery — A randomized controlled trial

Abstract Background Remote ischemic preconditioning (RIPC) has two time windows for organ protection: acute and delayed. Previous studies have mainly focused on the acute time window to evaluate organ protection by RIPC. We evaluated myocardial protection by delayed RIPC in adult patients undergoing cardiac surgery. Methods A total of 160 adult patients undergoing cardiac surgery with cardiopulmonary bypass were randomized to receive either delayed RIPC (four cycles of 5min of ischemia followed by 5min of reperfusion by inflation to 200mmHg and deflation of a blood pressure cuff on the upper arm) or the control treatment 24–48h before surgery. The primary endpoint was post-operative troponin I levels serially measured for 72h. Secondary endpoints included post-operative serum creatinine levels, acute kidney injury, and composite complications. Results There were no significant differences in post-operative troponin I values. The incidence of acute kidney injury, defined by the Acute Kidney Injury Network staging system, was lower in the delayed RIPC group compared to the control group (30.0% vs. 47.5%; relative risk, 0.768; 95% confidence interval, 0.599–0.985; p=0.023). Moreover, the occurrence of composite complications was lower in the delayed RIPC group compared with the control group (65.0% vs. 81.3%; relative risk, 0.536; 95% confidence interval, 0.311–0.924; p=0.020). Conclusions While RIPC did not provide cardioprotective effects in patients undergoing cardiac surgery, it appeared to reduce acute kidney injury, as well as the rate of composite complications.