A Novel Approach for Improving Renal Function
Impaired kidney function is frequently linked to the acute decompensation of chronic heart failure, indicating a grim prognosis. Current data reveals that patients with acute kidney injury experience worse survival rates during durable LVAD placement as bridge therapy compared to those with chronic kidney disease. Additionally, individuals with end-stage heart failure undergoing combined heart-kidney transplantation exhibit inferior short- and long-term survival compared to those undergoing heart transplants alone. In this study, scientists focused on kidney function recovery in heart failure patients awaiting transplantation, supported by temporary mechanical circulatory support (tMCS) with Impella 5.5.
Study Methods
In this study, protocol (#22004000) received approval from the Mayo Clinic institutional review board. Researchers conducted a retrospective review, considering patients with acute-on-chronic heart failure and kidney disease, evaluated for heart and kidney combined organ transplant, and supported by tMCS between January 2020 and February 2021. Hemodynamic and kidney function trends were scrutinized before and after tMCS placement and transplantation.
Out of 57 heart transplantation patients, six were considered for heart and kidney transplant while supported with Impella 5.5. The patients underwent extensive evaluation by the kidney transplant team. All patients had chronic heart failure diagnosed at least seven years before admission.
Post-tMCS insertion, researchers observed a positive trend in creatinine, Fick cardiac index, mixed venous saturation, and glomerular filtration rate (GFR), persisting through transplantation and discharge. The average tMCS support duration was 16.5 days before organ transplantation. The median pre-tMCS creatinine was 2.1 mg/dL (IQR 1.75–2.3). Hematocrit at tMCS placement was 32% (IQR 32–34), and the estimated GFR was 34 mL/min/BSA (34–40). GFR increased to 44 mL/min/BSA (IQR 45–51), and creatinine improved to 1.5 mg/dL (1.5–1.8) post-tMCS. At discharge, median creatinine was 1.1 mg/dL (1.19–1.25) with a GFR of 72 (65–74). Importantly, none of the six patients supported with tMCS necessitated renal replacement therapy post-heart transplantation. The early implementation of Impella 5.5 in this patient cohort resulted in renal recovery without the need for renal replacement therapies or dual organ transplantation, warranting further investigation.
Impaired kidney function is often associated with acute decompensation of chronic heart failure, signifying a poor prognosis. As heart failure progresses, advanced therapies become necessary, including transplantation or bridge therapies. Traditional bridge-to-transplant options, such as continuous inotrope therapy or durable left ventricular assist devices (LVAD), have shown worse survival in patients with acute kidney injury compared to chronic kidney disease during LVAD placement as bridge therapy.
National data from the Organ Procurement and Transplantation Network (OPTN) highlights the significance of simultaneous heart/kidney transplantation, with unclear information on potentially reversible kidney injury in recent cases. In patients with advanced heart failure, worsening kidney function often prompts consideration for kidney replacement therapy, correlating with poorer outcomes. Moreover, combined heart-kidney transplantation in end-stage heart failure patients exhibits inferior short- and long-term survival compared to heart transplants alone.
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Our study focused on kidney function recovery in chronic heart failure patients awaiting heart transplantation at our institution, supported by temporary mechanical circulatory support (tMCS) with Impella 5.5. Researchers observed sustained kidney function improvement in a subset of patients with the Impella 5.5 axillary tMCS device, a phenomenon not commonly seen with other bridge therapies.
Impella Management
Patients supported with Impella 5.5 were co-managed by transplant critical care, transplant cardiology, and cardiothoracic surgery. Standardized Impella care included weekly echocardiograms, hemodynamic assessments, and heparin-based purge solutions. Impella 5.5 candidacy was determined based on progressive left ventricular failure and worsening end-organ markers.
Results
Pre-Impella, patients exhibited a median creatinine of 2.1 mg/dL and an estimated glomerular filtration rate (GFR) of 34 mL/min/BSA. Post-Impella, there was a trend toward improvement in creatinine, Fick cardiac index, mixed venous saturation, and GFR. Median GFR improved from 34 to 44 mL/min/BSA, and serum creatinine decreased from 2.1 to 1.5 mg/dL. Post-transplant, none of the six patients required renal replacement therapy, and most had improved to CKD Stage 2.
Discussion
The underlying pathophysiology of cardiorenal syndrome involves dysfunction between the heart and kidneys, resulting in increased salt and fluid retention and oxidative stress. While evidence on renal recovery in cardiogenic shock patients supported with temporary mechanical circulatory support (tMCS) is limited, Impella 5.5 demonstrated a significant impact on kidney function improvement in our study.
Conclusion
Impella 5.5 use in patients with advanced heart failure and kidney disease resulted in renal recovery, with six patients avoiding the need for renal transplantation. The device’s minimally invasive placement, limited hemolysis profile, and biventricular offloading make Impella 5.5 a promising option for optimizing patients with advanced kidney disease awaiting organ transplantation in cardiogenic shock. Larger studies are warranted to further investigate these findings
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