Metabolomic profiling in patients undergoing Off-Pump or On-Pump coronary artery bypass surgery

BACKGROUND Coronary artery bypass surgery can be performed without (Off-Pump) or with cardiopulmonary bypass (On-Pump). Extracorporeal circulation and cardioplegic arrest may cause alterations in the plasma metabolome. We assessed metabolomic changes in patients undergoing On-Pump or Off-Pump coronary artery bypass surgery. METHODS We assessed five analyte classes (41 acylcarnitines, 14 amino acids, 92 glycerophospholipids, 15 sphingolipids, sugars, lactate) using a mass-spectrometry-based kit (Biocrates AbsoluteIDQ® p150) in paired arterial and coronary sinus blood obtained from 10 consecutive On-Pump and 10 Off-Pump patients. Cardioplegia for On-Pump was warm blood Calafiore. On-Pump outcomes were corrected for hemodilution through crystalloid priming. RESULTS Demographic data were equal in both groups with normal ejection fraction, renal and liver function. Patients received 2.25 ± 0.64 bypass grafts. All postoperative courses were uneventful. Of 164 measured metabolites, only 13 (7.9%) were altered by cardiopulmonary bypass. We found more long-chain acylcarnitines Off-Pump and more short-chain acylcarnitines On-Pump. Glycerophospholipids showed lower concentrations On-Pump and arginine (as the only different amino acid) Off-Pump. Interestingly, plasma arginine (nitric oxide precursor) concentration at the end of surgery correlated inversely with postoperative vasopressor need (r = -0.7; p < 0.001). Assessing arterial/venous differences revealed phosphatidylcholine-production and acylcarnitine-consumption. These findings were unaffected by cardiopulmonary bypass, cardioplegia or temporary vessel occlusion during Off-Pump surgery. CONCLUSIONS Cardiopulmonary bypass and warm blood cardioplegia cause only minor changes to the metabolomic profile of patients undergoing coronary artery bypass surgery. The observed changes affected mainly acylcarnitines. In addition, there appears to be a relationship between arginine and vasopressor need after bypass surgery.