Abstract 2527: Remote Ischemic Preconditioning Reduces Myocardial Injury After Aortic Aneurysm Repair
Myocardial injury is a significant cause of perioperative morbidity and mortality following abdominal aortic aneurysm (AAA) surgery. Subclinical myocardial injury, detected by rises in cardiac troponin I (TnI), are common and associated with reduced survival. Remote ischemic preconditioning is a phenomenon whereby a brief period of ischemia followed by reperfusion prior to prolonged ischemia can provide protection from cellular injury in distant organs. To investigate whether remote preconditioning could prevent myocardial injury in patients undergoing elective open AAA repair we performed a randomized trial.
METHODS AND RESULTS: Between February 2003 to December 2005, 82 patients were randomized to conventional AAA repair (control) or AAA repair with remote preconditioning. Two cycles of intermittent cross clamping of the common iliac artery with 10 minutes ischemia followed by 10 minutes reperfusion served as the preconditioning stimulus. Patients were screened for myocardial injury or infarction using symptomatic assessment, EKG and TnI measurements taken 1, 3, and 7 days after surgery. The patients were well matched for baseline characteristics. Remote preconditioning reduced the incidence of myocardial injury by 32% (9/41 vs 22/41; P=0.003) and myocardial infarction by 22% (2/41 vs 11/41; P=0.006). The adjusted relative risk of myocardial injury of 0.25 (0.08 to 0.82; P=0.02)and myocardial infarction of 0.18 (95% CI 0.04 to 0.75; P=0.006) were significantly lower in the remote preconditioning group. The mean TnI area-under-the-curve was reduced in the preconditioned group by 23.2 ng/mL·days (95% CI 7.5 to 76 [0.38±1.3 vs 24±87]; P<0.001). In contrast to direct preconditioning, remote preconditioning has the potential to provide a widespread and systemic benefit. Post-hoc analysis revealed the relative risk of renal impairment was lower (0.26, 0.06 to 1.05; P=0.06), and the mean creatinine area-under-the-curve reduced by 337 μmol/L·days (148 to 665; p=0.05) in the preconditioning group.
CONSLUSION: In patients undergoing elective AAA repair intermittent lower limb ischemia as a remote preconditioning stimulus significantly reduces myocardial injury and infarction. This simple maneuver has important clinical implications.