Impact of microaxial flow pumps on acute kidney injury in cardiogenic shock

Background Microaxial flow pumps (mAFP) can improve survival in STEMI-related cardiogenic shock (CS) but are associated with high complication rates, including acute kidney injury (AKI) and continuous veno-venous hemofiltration (CVVHD) use, as well as haemolysis. Purpose We aimed to evaluate the relationship between AKI and haemolysis, and the impact of these on short term clinical outcomes in patients with CS on mAFP support. Methods In a retrospective single centre study of patients with CS treated with left-sided mAFP, we evaluated the relationship between AKI, haemolysis and clinical outcomes on consecutive patients. Observational data collected as part of routine care were analysed. Results Among 82 patients (median [IQR] age: 57 [50-63] years, 82% male, median [IQR] BMI 25.0 [22.1-29.5]), CS was of ischaemic aetilogy in 51% and non-ischaemic in 49%. At baseline, 1% (n=1) had end-stage renal disease, and 12% (n=10) had chronic kidney disease (CKD, eGFR <60 mL/min/1.73m²). AKI occurred in 67% of patients (n=55/82), with 51% (n=42/82) requiring CVVHD. CVVHD was started in 82% of patients by day 2 post-mAFP implantation. Indications for CVVHD were anuria (49%), anuria with fluid overload (27%), fluid overload alone (16%), and acidosis (8%) (Figure 1). CVVHD duration was 7 [4-22] days (median [IQR]) . At initiation, median urine output was 10 mL/hour, with mean creatinine 243 ± 96 µmol/L, urea 17.6 ± 7.2 mmol/L, and potassium 4.7 ± 0.7 mmol/L. During mAFP, haemolysis (plasma-free haemoglobin >40 mg/dL) was more frequently observed in patients with AKI than those with out AKI (78% vs 22%, p= 0.0196) and in those requiring vs those not requiring CVVHD (64% vs 36%, p= 0.033) (Figure 1). Patients who required CVVHD had a much lower likelihood of successful weaning from mAFP (24% vs 54%, p=0.011) and higher 30-day mortality (51% vs 8%, p<0.0001). CVVHD patients also had lower likelihood of being bridged to transplantation with mAFP (4% vs 59%, p=0.0002). Conclusion Among patients with CS supported with mAFP, AKI and progression to CVVHD are extremely frequent. Haemolysis occurs more frequently in patients with AKI. AKI, and in particular CVVHD, is strongly associated with adverse outcomes, including higher mortality, lower recovery and transplantation rates. Further research is needed to evaluate the relationship between AKI and haemolysis and ways to reduce AKI in this cohort.