Association between haemolysis markers and neuron-specific enolase in acute myocardial infarction complicated by cardiogenic shock patients supported with a microaxial flow pump

Aims Acute myocardial infarction complicated by cardiogenic shock (AMICS) is frequently preceded by out-of-hospital cardiac arrest (OHCA), with risk of anoxic brain injury. Neuron-specific enolase (NSE) is central to neuroprognostication; however, concomitant haemolysis can increase NSE independent of neuronal injury due to the presence of NSE in erythrocytes. This consideration is critical in AMICS patients treated with a microaxial flow pump (Impella, Abiomed, Danvers, MA, USA), where haemolysis is frequent. Methods and results We identified consecutive AMICS patients receiving microaxial flow pump support ≥6 h from 2014 to 2022 in a tertiary Danish heart centre. Peak NSE and haemolysis biomarkers within 72 h following microaxial flow pump placement were used for analysis. Haemolysis was defined as plasma-free haemoglobin levels >31.5 µmol/L within 72 h from device placement. The population was stratified according to the presence or absence of haemolysis. The final study population comprised 44 patients with eligible NSE and haemolysis biomarkers. The median NSE was 85 µg/L. Patients with haemolysis had significantly higher NSE levels than those without (115 vs. 69 µg/L, P = 0.018). Neuron-specific enolase levels were similar between OHCA and non-OHCA patients. No significant difference in death from anoxic brain injury was observed between patients with NSE levels above and below 60 µg/L. Neuron-specific enolase revealed a significantly moderate correlation with all investigated haemolysis markers. Conclusion Neuron-specific enolase was associated with haemolysis, and not anoxic brain injury, in AMICS patients supported with a microaxial flow pump.