Effects of intense remote ischemic preconditioning in patients undergoing elective off-pump coronary artery bypass graft surgery: a pilot study

Background
Remote ischemic preconditioning (RIPC) of the myocardium by upper-limb or lower-limb ischemia/reperfusion may reduce myocardial injury during cardiac surgery. We conducted a single-centered, prospective, randomized controlled trial to evaluate if intense RIPC by inducing ischemia/reperfusion in both the upper arm and thigh simultaneously can reduce myocardial injury in patients undergoing elective off-pump coronary artery bypass graft surgery.
Patients and methods
In total, 47 adult patients were randomized to receive either intense RIPC protocol (=23) or control (=24), after induction of general anesthesia but before the surgical incision. Patients in the RIPC group were subjected to three 5-min cycles of ischemia, induced by inflating two standard blood-pressure cuffs placed simultaneously on the upper arm and thigh to 200 mmHg, with an intervening 5 min of reperfusion, achieved by deflation of these cuffs. In the control group, the two blood-pressure cuffs were left uninflated for 30 min. Anesthesia was maintained with sevoflurane, remifentanil and rocuronium/cisatracurium. Perioperative myocardial injury was assessed by measuring serum levels of cardiac biomarkers [cardiac troponin I (cTnI), creatine kinase isoform-MB (CKMB), and N-terminal of the prohormone brain natriuretic peptide (NTproBNP)] preoperatively and at 24 and 72 h after the end of surgery.
Results
There was no significant difference in the postoperative release of cardiac biomarkers between the two groups: cTnI at 24 h [median (lower, upper quartiles), 1.16 (0.42, 4.69) ng/ml in RIPC vs. 0.83 (0.54, 1.93) ng/ml in controls, =0.987] and at 72 h [0.28 (0.08, 1.79) ng/ml in RIPC vs. 0.48 (0.17, 2.34) ng/ml in controls, =0.534]; CKMB at 24 h [4.2 (2.15, 14.15) ng/ml in RIPC vs. 7.3 (2.68, 12.5) ng/ml in controls, =0.597] and at 72 h [1.6 (0.7, 4.85) ng/ml in RIPC vs 1.6 (0.9, 2.5) ng/ml in controls, =0.902]; NTproBNP at 24 h [1510 (808, 3528) pg/ml in RIPC vs. 1584 (972, 3055) pg/ml in controls, =0.958] and at 72 h [1459 (815, 3645) pg/ml in RIPC vs. 2677 (1292, 4804) pg/ml in controls, =0.304]. There was no significant difference in inotrope score at the end of surgery (=0.631) and duration of postoperative hospital stay (=0.818) between the two groups.
Conclusion
Intense RIPC did not cause significant reduction in the postoperative release of cardiac biomarkers (cTnI, CKMB, and NTproBNP) in patients undergoing elective off-pump coronary artery bypass graft surgery.