Effect of limb ischemic preconditioning on myocardial injury in patients undergoing mitral valve replacement surgery: A randomized controlled trial

Abstract

Background: Whether limb ischemic preconditioning (LIPC) is beneficial for patients undergoing mitral valve replacement (MVR) surgery is unknown. Methods and Results: Seventy-five adult patients undergoing MVR surgery were randomly assigned to 3 groups: control group (n=25), LIPC group I (3×5-min cycles of right upper arm ischemia and 5-min reperfusion; n=25) and LIPC group II (3×5-min cycles of right upper arm ischemia and 5-min reperfusion combined with 2×10-min cycles of right upper leg ischemia and 10-min reperfusion; n=25). Cardiopulmonary bypass (CPB) time, cross-clamp time, cardiac index, cumulative postoperative dosage of dobutamine, intensive care stay, postoperative hospital stay were not statistically different. Although the cumulative postoperative dosage of dobutamine was not different, there was a significantly lower inotropic requirement in LIPC II compared with the control group at 4 and 8 h after surgery. Plasma levels of cardiac troponin-I in the 3 groups significantly increased during CPB and peaked at 4 h after surgery. Levels of cTnI in LIPC II were significantly lower than in the control group at each time point after surgery. Conclusions: Myocardial injury is obvious after MVR surgery. LIPC can protect the myocardium from ischemia-reperfusion injury and decrease the inotropic requirement after surgery. The data also confirmed the requirement for the preconditioning stimulus to cross a threshold.