Repeated Episodes of Remote Ischemic Preconditioning for the Prevention of Myocardial Injury in Vascular Surgery

Abstract

Objectives: Remote ischemic preconditioning (RIPC) involves the phenomenon whereby transient episodes of limb ischemia induced by cuff inflation provide cardioprotection. The effectiveness of RIPC in vascular surgery is uncertain. This randomized, controlled trial was designed to investigate the potential of two episodes of RIPC to provide myocardial protection in patients undergoing vascular surgery. Design and Methods: Patients undergoing an elective major vascular procedure (open abdominal aortic aneurysm (AAA) repair, endovascular aneurysm repair, and lower-limb bypass grafting) were randomized into RIPC group (n = 42) or control group (n = 43). Remote ischemic preconditioning consisted of three 5-minute cycles of upper limb cuff occlusion with 5-minutes of reperfusion between cycles, both 24 hours and immediately before surgery. Control patients received a similarly timed sham treatment. Cardiac high-sensitivity troponin T (hsTnT) concentration was measured in plasma at 6, 12, 24, and 48 hours post-surgery, and at 72, 96, and 120 hours in patients still in hospital. Perioperative clinical adverse events and readmissions within ∼12 months were recorded. Results: Myocardial injury was demonstrated perioperatively in 43% of RIPC patients and 49% of controls, as defined by a significant hsTnT elevation. These incidences were statistically equivalent (odds ratio 0.79, 95% confidence interval 0.33-1.85, P = .58). The 48-hour area under the curve for hsTnT change from baseline also revealed no difference (RIPC vs control median: 5.3 vs 7.5 ng/L.h, P = .22). Each group had one type I and one type II myocardial infarction and no difference in complications or readmissions. Conclusions: This trial could not confirm that two episodes of RIPC reduce myocardial injury following vascular surgery. Along with other equivocal studies, it appears that RIPC does not induce a clear benefit in vascular surgery.