Cardioprotective Effect of Low Level of LDL Cholesterol on Perioperative Myocardial Injury in Off-Pump Coronary Artery Bypass Grafting

Abstract

Background and Objectives: Coronary artery disease is still a major cause of death in developed countries. Low-density lipoprotein cholesterol (LDL-C) lowering with statin therapy is a key strategy in major acute coronary events’ prevention. The aim of the study was to establish if there is a cardioprotective effect of pre-operative LDL lowering therapy on perioperative myocaridal injury in patients undergoing off-pump coronary artery bypass grafting (CABG). Moreover, the impact of pre-operative LDL level on long term outcome was analysed. Materials and Methods: The retrospective single center analysis included 662 consecutive patients (431 (65%) males and 231 (35%) female, mean age of 65 ± 8) referred for cardiac surgery due to stable chronic coronary syndrome between 2012–2018. The follow up was 9 years. Results: A statistically significant difference was found in postoperative serum Troponin-I for LDL thresholds of 1.8 mmol/L (p = 0.009), 2.6 mmol/L (p = 0.03) and 3.0 mmol/L (p = 0.001). The results indicate that cardioprotective role of LDL is achieved within LDL concentration rate below 1.8 mmol/L (<70 mg/dL). Five patients died perioperatively, whereas 1-year and 9-year overall mortality rates were 4% (n = 28) and 18.6% (n = 123), respectively. Comparing the survival group with diseased, Mann-Whitney U test showed a statistically significant difference in HDL-C (p = 0.007), Troponin (p = 0.009), Castelli index (p = 0.001) and atherogenic index (p = 0.004). Preoperative levels of total cholesterol, LDL-C and HDL-C did not significantly differ between survivors and diseased. The 9-year mortality risk did not differ significantly between subgroups divided according to LDL-C thresholds of 1.4 mmol/L (55 mg/dL), 1.8 mmol/L (70 mg/dL), 2.6 mmol/L (100 mg/dL) and 3.0 mmol/L (116 mg/dL). Conclusions: Preoperative low level of LDL-C cholesterol (below 1.83 mmol/L, 70 mg/dL) has a cardioprotective effect on perioperative myocardial injury in off-pump coronary artery bypass grafting.