Introduction: Off-pump coronary artery bypass graft surgery (OPCABG) causes less myocardial injury than surgery using bypass . But ischaemia of the normothermic beating heart might be harmful. In this study, we compared the efficacy of diltiazem and nitroglycerin for myocardial protection by measuring creatine phosphokinase-myocardial isoenzyme (CKMB), troponin-I and myoglobin during OPCABG.
Method: After ethics approval, 32 patients (ASA II-III; LVEF >40%; LVEDP < 18 mmHg) scheduled for OPCABG were randomized in two groups prospectively. Patients received an infusion of either nitroglycerin (1 μg kg−1 min−1, group N, n = 16) or diltiazem (0.1 mg kg−1 hr−1, group D, n = 16), after anaesthesia induction, during surgery and 24 hours postoperatively. Haemodynamic measurements including HR, MAP, CVP, MPAP, PCWP, CO and blood sampling for determination of CK-MB, troponin-I and myoglobin levels were made at the following times: before the anaesthesia induction (1), before and after the myocardial revascularization (2,3) and at 1, 4, 12 and 24 hours after surgery (4-7). Also cardiac complications (hypotension, hypertension, dysrhythmia, pulmonary hypertension, myocardial ischaemia) observed perioperatively were recorded. Wilcoxon's signed rank, Mann-Whitney U, chi-squared and Fisher's exact tests were used for statistical analysis.
Result: The two study groups did not differ with respect to demographic data and preoperative properties of patients. The increases in myoglobin, troponin-I and CK-MB, especially after the second measurement point, were significant in both groups (P < 0.05, P < 0.01, P < 0.001 in Group N and D).
No haemodynamic parameters differed significantly between the two groups. Observed cardiac complications were similar, except the lower postoperative incidence of dysrhythmia in Group D (8 vs. 2 patients; P < 0.05).
Discussion: The results showed that diltiazem infusion is more efficient for myocardial protection than nitroglycerin in OPCABG patients.
1 Czerny M, Baumer H, Kilo J, et al. Inflammatory response and myocardial injury following coronary artery bypass grafting with or without cardiopulmonary bypass. Eur J Cardiothorac Surg