Purpose: This study was conducted to evaluate the effects of ischemic preconditioning (IP) with a short period of reperfusion (2 min) during brief ischemic preconditioning (6 min) on patients undergoing coronary artery bypass grafting (CABG).
Methods: In a randomized controlled trial, 40 patients undergoing on-pump CABG with cold blood cardioplegia were allocated into two groups, one IP and one control. IP was induced by 2 cycles of ascending aorta clamping (2 min for each) followed by two reperfusion phases (1 min for each). Left ventricular ejection fraction (LVEF) was measured before and after surgery. Creatine phosphokinase (CK) and CK-MB were measured 12 hrs before surgery, immediately after aortic clamping, and 24 hrs after CABG. Postoperative myocardial infarction (MI), ventricular arrhythmia, duration of inotropic support, and hemodynamic parameters were also noted.
Results: More patients in the control group needed inotropic support (65% vs. 40%, P<0.05). Moreover, duration of inotropic support was longer in the control group (9 ± 1.2 vs. 3.8 ± 1.4 hrs, P<0.05). There were no significant differences between two groups regarding development of ventricular arrhythmia, MI, values of CK, CK-MB, and postoperative LVEF. No patient needed an intra-aortic balloon pump, and no deaths occurred.
Conclusion: A short period of reperfusion phase declined post-CABG inotrope requirements; however, it did not reduce the cardiac enzymes. Our results suggested that reperfusion should be longer than 2 min to be capable of reducing cardiac enzymes.