Glutamine is cardioprotective in patients with ischemic heart disease following cardiopulmonary bypass

Background: The aim of the present study was to investigate the cardioprotective effects of the perioperative use of N(2)-l-alanyl-l-glutamine (GLN) in patients with ischemic heart disease (IHD) who undergo their operations under cardiopulmonary bypass (CPB). Methods: This double-blind, placebo-controlled, randomized study included 50 patients who underwent cardiac surgery with CPB. Exclusion criteria were a left ventricular ejection fraction <50%, diabetes mellitus, <3 months since the onset of myocardial infarction, and emergency surgery. Patients in the study group (n = 25) received 0.4 g/kg GLN (Dipeptiven, 20% solution) per day. Patients in the control group (n = 25) were administered a placebo (0.9% NaCl). The primary end point was the dynamics of troponin I at the following stages: (1) prior to anesthesia, (2) 30 minutes after CPB, (3) 6 hours after CPB, (4) 24 hours after surgery, and (5) 48 hours after surgery. Secondary end points included measurements of hemodynamics with a Swan-Ganz catheter. Results: On the fi rst postoperative day after the surgery, the median troponin I level was signifi cantly lower in the study group than in the placebo group: 1.280 ng/mL (interquartile range [IQR], 0.840-2.230 ng/mL) versus 2.410 ng/mL (IQR, 1.060-6.600 ng/mL) (P = .035). At 4 hours after cardiopulmonary bypass (CPB), the median cardiac index was higher in the patients in the study group: 2.58 L/min per m ² (IQR, 2.34- 2.91 L/min per m ²) versus 2.03 L/min per m ² (IQR, 1.76- 2.32 L/min per m ²) (P = .002). The median stroke index also was higher in the patients who received GLN: 32.8 mL/m ²(IQR, 27.8-36.0 mL/m ²) versus 26.1 mL/m ² (IQR, 22.6- 31.8 mL/m ²) (P = .023). The median systemic vascular resistance index was signifi cantly lower in the study group than in the placebo group: 1942 dyn·s/cm ⁵ per m ² (IQR, 1828-2209 dyn·s/cm ⁵ per m ²) versus 2456 dyn?s/cm5 per m2 (IQR, 2400- 3265 dyn?s/cm5 per m2) (P = .001). Conclusion: Perioperative administration of GLN during the fi rst 24 hours has cardioprotective effects in IHD patients following CPB. This technique enhances the troponin concentration at 24 hours after surgery and is associated with improved myocardial function.