ABSTRACT
BACKGROUND: Although coronary artery bypass graft (CABG) surgery has been reported to be one of the most effective internentions in terms of myocardial salvage, reperfusion itself can cause additional damage to the myocardium. Since there is strong evidence that free radicals are the principal offender in ischemia-reperfusion (I/R) injury, it has been suggested that treatment with antioxidant agents can be protective. Investigations have shown that melatonin secretion is partially disturbed in CABG patients. The aim of this study was to evaluate the protective effect of melatonin as an antioxidant agent on I/R injury. METHODS: 164 elective CABG candidates participated in this randomized clinical trial during the preoperative period. The candidates were randomized to receive 3 mg of melatonin tablets (physiologic dose) from 3 days before surgery until the day of discharge. Cardiac biomarkers [troponin and creatine kinase myocardial band (CKMB)] were assessed once before surgery (24 hours before surgery), and 8 and 24 hours after surgery. RESULTS: Finally, 130 patients, 65 (50%) patients in the melatonin group and 65 (50%) in the control arm finished our study. Mean age of melatonin and control groups was 59.90 ± 9.59 and 60.80 ± 8.00 years, respectively; moreover, 47 (72.30%) in melatonin and 45 (69.23%) in control group were men. No significant difference was seen in baseline cardiac biomarkers between two groups (P > 0.05). In both groups, cardiac biomarkers (CKMB and troponin) elevated after surgery in comparison to their preoperative values. There was no statistically significant difference between the control and melatonin groups regarding the 8-hour and 24-hour troponin and CKMB when adjusted for interacting factors (P > 0.05). CONCLUSION: Although physiological concentration of melatonin is protective against I/R injury, substitution of endogenous melatonin with the oral supplement which creates physiologic concentration may not prevent I/R injury. In order to have antioxidant effect, pharmacologic doses of melatonin should be employed.
ABSTRACT
BACKGROUND: Acute kidney injury (AKI) is a common and life-threatening complication following coronary artery bypass graft (CABG). Neutrophil gelatinase-associated lipocalin (NGAL) and Cystatin C have shown to be good predictive factors for AKI. Recently, there has been a growing interest in the use of hypertonic saline in cardiac operations. The purpose of this study was to evaluate the prophylactic anti-inflammatory effect of hypertonic saline (Group A) infusion versus normal saline (Group B) on serum NGAL and Cystatin C levels as the two biomarkers of AKI in CABG patients. METHODS: This randomized double-blinded clinical trial recruited 40 patients undergoing CABG in Tehran Heart Center, Tehran, Iran. After applying exclusion criteria, the effects of preoperative hypertonic saline (294 meq Na) versus normal saline (154 meq Na) infusion on serum NGAL and Cystatin C levels were investigated in three intervals: before surgery and 24 and 48 hours postoperatively. The probable intraoperative or postoperative confounders, including pump time, cross-clamp time, heart rate, systolic and diastolic blood pressures, central venous pressure, arterial pH, partial pressure of arterial oxygen, fraction of inspired oxygen, blood sugar, Na, K, Mg, hemoglobins, white blood cells, hematocrits, and platelets, were recorded and compared between the two groups of study. RESULTS: The study population comprised 40 patients, including 25 (62.5%) males, at a, mean age ± SD of 61.75 ± 8.13 years. There were no statistically significant differences between the patients' basic, intraoperative, and postoperative characteristics, including intraoperative and postoperative hemodynamic variables and supports such as inotropic use. Intra-aortic balloon pump use and mortality were not seen in our cases. Three patients in the normal saline group and one patient in the hypertonic saline group had serum NGAL levels greater than 400 ng/ml. Moreover, 10 patients in Group A and 17 patients in group B showed a rise in serum Cystatin C levels above 1.16 mg/dl. Patients with AKI had significantly elevated NGAL and Cystatin C levels (p value < 0.001), but there were no significant differences in the decrease in the NGAL level in the hypertonic saline group versus the normal saline group (230.91 ± 92.68 vs. 239.74 ± 116.58 ng/ml, respectively; p value = 0.792), or in the decrease in the Cystatin C level in the hypertonic saline group versus the normal saline group (1.05 ± 0.26 vs. 1.06 ± 0.31, respectively; p value = 0.874). CONCLUSION: Pre-treatment of CABG patients with hypertonic saline had no significant effect on serum NGAL and Cystatin C levels compared to the normal saline-receiving group. Our present data, albeit promising, have yet to fully document outcome differences.
