Renal dysfunction and chronic mechanical circulatory support: from patient selection to long-term management and prognosis

Urinary biomarkers associated with acute kidney injury in pediatric mechanical circulatory support patients

BACKGROUND

In patients requiring mechanical circulatory support (MCS), the incidence of acute kidney injury (AKI) is between 37 and 63%. In this study, we performed an exploratory analysis evaluating the relationship of multiple urine biomarkers with AKI development in pediatric MCS patients.

METHODS

This is a single center retrospective study in a pediatric cohort receiving MCS from August 2014 to November 2020. We measured 14 urine biomarkers of kidney injury on day 1 following MCS initiation and analyzed their association with development of AKI in the first 7 days of MCS initiation.

RESULTS

Sixty patients met inclusion criteria. Patients with AKI were more likely to be supported by venoarterial extracorporeal membrane oxygenation (65% vs. 8.3%, p < 0.001), compared to the no AKI group and less likely to have ventricular assist devices (10% vs. 50%, p < 0.001). There was a significant increase in the median urine albumin and urine osteoactivin in the AKI group, compared to the no AKI group (p = 0.020 and p = 0.018, respectively). When normalized to urine creatinine (UCr), an increased log osteoactivin/UCr was associated with higher odds of AKI development (OR: 2.05; 95% CI: 1.07, 4.44; p = 0.028), and higher log epidermal growth factor (EGF)/UCr (OR: 0.41; 95% CI: 0.15, 0.96) was associated with decreased odds of AKI.

CONCLUSIONS

Early increase in urine osteoactivin is associated with AKI development within 7 days of MCS initiation in pediatric patients. Contrary, an increased urine EGF is associated with kidney protection. A higher resolution version of the Graphical abstract is available as Supplementary information.

The trajectory of renal function following mechanical circulatory support and subsequent heart transplantation

Aim

Patients with advanced heart failure (HF) frequently suffer from renal insufficiency. The impact of durable mechanical circulatory support (MCS) and subsequent heart transplantation (HTx) on kidney function is not well described.

Methods and results

We studied patients with advanced HF who received durable MCS as bridge to transplantation (BTT) and underwent subsequent HTx at our centre between 1996 and 2018. Glomerular filtration rate (GFR) was measured by ⁵¹Cr‐EDTA or iohexol clearance during heart failure work‐up; 3–6 months after MCS; and 1 year after HTx. Chronic kidney disease (CKD) was classified according to KDIGO criteria based on estimated GFR. A total of 88 patients (46 ± 15 years, 84% male) were included, 63% with non‐ischaemic heart disease. The median duration of MCS‐treatment was 172 (IQR 116–311) days, and 81 subjects were alive 1 year after HTx. Measured GFR increased from 54 ± 19 during HF work‐up to 60 ± 16 mL/min/1.73 m² after MCS (P < 0.001) and displayed a slight but nonsignificant decrease to 57 ± 22 mL/min/1.73 m² 1 year after HTx (P = 0.38). The trajectory of measured GFR did not differ between pulsatile and continuous flow (CF) pumps. Among patients 35–49 years and those who were treated in the most recent era (2012–2018), measured GFR increased following MCS implantation and subsequent HTx. Estimated GFR displayed a similar course as did measured GFR.

Conclusions

In patients with advanced heart failure, measured GFR improved after MCS with no difference between pulsatile and CF‐pumps. The total study group showed no further increase in GFR following HTx, but in certain subgroups, including patients aged 35–54 years and those treated during the latest era (2012–2018), renal function appeared to improve after transplant.

HFA of the ESC position paper on the management of LVAD-supported patients for the non-LVAD specialist healthcare provider Part 3: at the hospital and discharge

The growing population of left ventricular assist device (LVAD)‐supported patients increases the probability of an LVAD‐ supported patient hospitalized in the internal or surgical wards with certain expected device related, and patient‐device interaction complication as well as with any other comorbidities requiring hospitalization. In this third part of the trilogy on the management of LVAD‐supported patients for the non‐LVAD specialist healthcare provider, definitions and structured approach to the hospitalized LVAD‐supported patient are presented including blood pressure assessment, medical therapy of the LVAD supported patient, and challenges related to anaesthesia and non‐cardiac surgical interventions. Finally, important aspects to consider when discharging an LVAD patient home and palliative and end‐of‐life approaches are described.

Cardiac Outcomes in Isolated Heart and Simultaneous Kidney and Heart Transplants in the United States

Introduction

Kidney dysfunction is not uncommon in patients with advanced heart failure. Simultaneous kidney and heart transplants (SKHTs) have gained acceptance as a treatment for patients with end-stage heart failure and severe kidney dysfunction. United States saw a rise of 650% in SKHT from 2000 to 2019. Despite increasing number of SKHT, the selection criteria remain poorly defined and vary across transplant centers.

Methods

We evaluated patient and cardiac allograft survival for SKHT and heart transplant alone (HTA) using the United Network for Organ Sharing (UNOS) database. We then performed a subgroup analysis in recipients with post-transplant acute kidney injury requiring renal replacement therapy (RRT) and compared outcomes between SKHT and HTA recipients.

Results

Although patient survival was comparable between SKHT and HTA groups (12.4 vs. 11.3 years), patients dependent on dialysis pretransplant derived greater survival advantage from SKHT as compared with HTA (12.4 vs. 9.9 years). Cardiac graft survival was better in SKHT (12.5 vs. 11.2 years). Among patients who developed acute kidney injury requiring RRT postoperatively, SKHT recipients had a significantly better survival (11.9 vs. 2.7 years).

Conclusion

Our data support consideration of SKHT in dialysis-dependent heart transplant candidates and suggest that patients who are at increased risk of requiring RRT after heart transplant may benefit from SKHT.

Impact of Continuous Flow Left Ventricular Assist Device Therapy on Chronic Kidney Disease: A Longitudinal Multicenter Study

BACKGROUND

Many patients undergoing durable left ventricular assist device (LVAD) implantation suffer from chronic kidney disease (CKD). Therefore, we investigated the effect of LVAD support on CKD.

METHODS

A retrospective multicenter cohort study, including all patients undergoing LVAD (HeartMate II (n = 330), HeartMate 3 (n = 22) and HeartWare (n = 48) implantation. In total, 227 (56.8%) patients were implanted as bridge-to-transplantation; 154 (38.5%) as destination therapy; and 19 (4.7%) as bridge-to-decision. Serum creatinine measurements were collected over a 2-year follow-up period. Patients were stratified based on CKD stage.

RESULTS

Overall, 400 patients (mean age 53 ± 14 years, 75% male) were included: 186 (46.5%) patients had CKD stage 1 or 2; 93 (23.3%) had CKD stage 3a; 82 (20.5%) had CKD stage 3b; and 39 (9.8%) had CKD stage 4 or 5 prior to LVAD implantation. During a median follow-up of 179 days (IQR 28-627), 32,629 creatinine measurements were available. Improvement of kidney function was noticed in every preoperative CKD-stage group. Following this improvement, estimated glomerular filtration rates regressed to baseline values for all CKD stages. Patients showing early renal function improvement were younger and in worse preoperative condition. Moreover, survival rates were higher in patients showing early improvement (69% vs 56%, log-rank P = 0 .013).

CONCLUSIONS

Renal function following LVAD implantation is characterized by improvement, steady state and subsequent deterioration. Patients who showed early renal function improvement were in worse preoperative condition, however, and had higher survival rates at 2 years of follow-up.

Cystatin C- Versus Creatinine-Based Assessment of Renal Function and Prediction of Early Outcomes Among Patients With a Left Ventricular Assist Device

BACKGROUND

Estimated glomerular filtration rate (eGFR) based on serum creatinine (sCr) improves early after left ventricular assist device (LVAD) implantation but subsequently declines. Although sCr is a commonly accepted clinical standard, cystatin C (CysC) has shown superiority in assessment of renal function in disease states characterized by muscle wasting. Among patients with an LVAD, we aimed to (1) longitudinally compare CysC-eGFR and sCr-eGFR, (2) assess their predictive value for early postoperative outcomes, and (3) investigate mechanisms which might explain potential discrepancies.

METHODS

A prospective cohort (n=116) with CysC and sCr concurrently measured at serial time points, and a retrospective cohort (n=91) with chest computed tomography performed within 40 days post-LVAD were studied. In the prospective cohort, the primary end point was a composite of in-hospital mortality, renal replacement therapy, or severe right ventricular failure. In the retrospective cohort, muscle mass was estimated using pectoralis muscle area indexed to body surface area (pectoralis muscle index).

RESULTS

In the prospective cohort, sCr-eGFR significantly improved early post-LVAD and subsequently declined, whereas CysC-eGFR remained stable. CysC-eGFR but not sCr-eGFR predicted the primary end point: odds ratio per 5 mL/(min·1.73 m²) decrease 1.16 (1.02-1.31) versus 0.99 (0.94-1.05). In retrospective cohort, for every 5 days post-LVAD, a 6% decrease in pectoralis muscle index was observed (95% CI, 2%-9%, P=0.003). After adjusting for time on LVAD, for every 1 cm²/m² decrease in pectoralis muscle index, there was a 4% decrease in 30-day post-LVAD sCr (95% CI, 1%-6%, P=0.004).

CONCLUSIONS

Initial improvement in sCr-eGFR is likely due to muscle wasting following LVAD surgery. CysC may improve assessment of renal function and prediction of early postoperative outcomes in patients with an LVAD.

Cardiorenal Syndrome Revisited

Cardiorenal syndromes have been categorized into 5 clinical subtypes based on which organ is perceived to be the primary precipitant of the vicious and interrelated cycle of declining function in both organs. This clinical classification has broadened interest in cardiorenal interactions, but it is merely descriptive, does not rely on or inform predominant pathophysiology, and has produced little change in either practice or the research agenda. In contrast, recent scientific work identifies common pathophysiological pathways for several categories of cardiorenal syndromes, suggesting a unifying pathogenesis. Fibrosis is a common consequence of inflammation- and oxidative stress-related endothelial dysfunction in aging, hypertension, diabetes mellitus, obesity, ischemia, and organ injury. It is a common feature in heart failure and chronic kidney disease. Therefore, we suggest that fibrosis may be not only a marker but also the primary driver of pathophysiology in several cardiorenal syndromes. Interstitial fibrosis in the heart, large arteries, and kidneys may play a key role in the pathophysiology of the cardiorenal syndrome continuum. Focusing on fibrosis as a disease mediator might enable the identification of fibrosis-related biotargets that could potentially be modulated with renin-angiotensin-aldosterone system inhibitors, mineralocorticoid receptor antagonists, or other novel antifibrotic agents in development. This conceptual approach may be an effective new strategy for the prevention and treatment of fibrosis within the cardiorenal syndrome continuum.