Early risk predictors of acute kidney injury and short-term survival during Impella support in cardiogenic shock.

Acute kidney injury (AKI) is one of the most frequent and prognostic-relevant complications of cardiogenic shock (CS) complicating myocardial infarction (MI). Mechanical circulatory assist devices (MCS) like left ventricular Impella microaxial pump have increasingly been used in the last decade for stabilization of hemodynamics in those patients. Moreover, a protective effect of Impella on renal organ perfusion could recently be demonstrated. However, data identifying early risk predictors for developing AKI during Impella support in CS are rare. Data of hemodynamics and renal function from 50 Impella patients (January 2020 and February 2022) with MI-related CS (SCAI stage C), were retrospectively analyzed using e.g. multivariate logistic regression analysis as well as Kaplan-Meier curves and Cox regression analysis. 30 patients (60%) developed AKI. Central venous pressure as an indicator for venous congestion (OR 1.216, p = 0.02), GFR at admission indicating existing renal damage (OR 0.928, p = 0.002), and reduced central venous oxygen saturation (SvO2) as a marker for decreased tissue perfusion (OR 0.930, p = 0.029) were independently associated with developing an AKI. The 30-day mortality rate was significantly higher in patients with AKI stage 3 (Stage 1: 0%, Stage 2: 0%, Stage 3; 41.6%, p = 0.014) while AKI stage 3 (HR 0.095, p = 0.026) and norepinephrine dosage (HR 1.027, p = 0.008) were independent predictors for 30-day mortality. AKI as a complication of MI-related CS occurs frequently with a major impact on prognosis. Venous congestion, reduced tissue perfusion, and an already impaired renal function are independent predictors of AKI. Thus, timely diagnostics and a focused treatment of the identified factors could improve prognosis and outcome.

Discussion of hemodynamic optimization strategies and the canonical understanding of hemodynamics during biventricular mechanical support in cardiogenic shock: does the flow balance make the difference?

BACKGROUND: Mechanical circulatory support (MCS) devices may stabilize patients with severe cardiogenic shock (CS) following myocardial infarction (MI). However, the canonical understanding of hemodynamics related to the determination of the native cardiac output (CO) does not explain or support the understanding of combined left and right MCS. To ensure the most optimal therapy control, the current principles of hemodynamic measurements during biventricular support should be re-evaluated. METHODS: Here we report a protocol of hemodynamic optimization strategy during biventricular MCS (VA-ECMO and left ventricular Impella) in a case series of 10 consecutive patients with severe cardiogenic shock complicating myocardial infarction. During the protocol, the flow rates of both devices were switched in opposing directions (+ / - 0.7 l/min) for specified times. To address the limitations of existing hemodynamic measurement strategies during biventricular support, different measurement techniques (thermodilution, Fick principle, mixed venous oxygen saturation) were performed by pulmonary artery catheterization. Additionally, Doppler ultrasound was performed to determine the renal resistive index (RRI) as an indicator of renal perfusion. RESULTS: The comparison between condition 1 (ECMO flow > Impella flow) and condition 2 (Impella flow > VA-ECMO flow) revealed significant changes in hemodynamics. In detail, compared to condition 1, condition 2 results in a significant increase in cardiac output (3.86 ± 1.11 vs. 5.44 ± 1.13 l/min, p = 0.005) and cardiac index (2.04 ± 0.64 vs. 2.85 ± 0.69, p = 0.013), and mixed venous oxygen saturation (56.44 ± 6.97% vs. 62.02 ± 5.64% p = 0.049), whereas systemic vascular resistance decreased from 1618 ± 337 to 1086 ± 306 s*cm-5 (p = 0.002). Similarly, RRI decreased in condition 2 (0.662 ± 0.05 vs. 0.578 ± 0.06, p = 0.003). CONCLUSIONS: To monitor and optimize MCS in CS, PA catheterization for hemodynamic measurement is applicable. Higher Impella flow is superior to higher VA-ECMO flow resulting in a more profound increase in CO with subsequent improvement of organ perfusion.