Association between hemolysis markers and neuron-specific enolase in AMICS patients supported with a microaxial flow pump

Abstract

Background: 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 hemolysis 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), where hemolysis is frequent.

Methods and results: We identified consecutive AMICS patients receiving microaxial flow pump support ≥6h from 2014 to 2022 in a tertiary Danish heart center. Peak NSE and hemolysis biomarkers within 72h following microaxial flow pump placement were used for analysis. Hemolysis was defined as plasma-free hemoglobin levels >31.5 µmol/L within 72h from device placement. The population was stratified according to the presence or absence of hemolysis.The final study population comprised 44 patients with eligible NSE and hemolysis biomarkers. The median NSE was 85 µg/L. Patients with hemolysis had significantly higher NSE levels than those without (115 vs. 69 µg/L, p=0.018). NSE 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 or below 60 µg/L. NSE revealed a significantly moderate correlation with all investigated hemolysis markers.

Conclusions: NSE was associated with hemolysis, and not anoxic brain injury, in AMICS patients supported with a microaxial flow pump.

Keywords: Acute Myocardial Infarction; Cardiogenic shock; Hemolysis; Microaxial flow pump; Neuron-specific enolase.