Renal function and outcome after continuous flow left ventricular assist device implantation

Long-term kidney outcomes in pediatric continuous-flow ventricular assist device patients

BACKGROUND

Continuous-flow ventricular assist devices (CF-VADs) are used increasingly in pediatric end-stage heart failure (ESHF) patients. Alongside common risk factors like oxidant injury from hemolysis, non-pulsatile flow constitutes a unique circulatory stress on kidneys. Post-implantation recovery after acute kidney injury (AKI) is commonly reported, but long-term kidney outcomes or factors implicated in the evolution of chronic kidney disease (CKD) with prolonged CF-VAD support are unknown.

METHODS

We studied ESHF patients supported > 90 days on CF-VAD from 2008 to 2018. The primary outcome was CKD (per Kidney Disease Improving Global Outcomes (KDIGO) criteria). Secondary outcomes included AKI incidence post-implantation and CKD evolution in the 6-12 months of CF-VAD support.

RESULTS

We enrolled 134 patients; 84/134 (63%) were male, median age was 13 [IQR 9.9, 15.9] years, 72/134 (54%) had preexisting CKD at implantation, and 85/134 (63%) had AKI. At 3 months, of the 91/134 (68%) still on a CF-VAD, 34/91 (37%) never had CKD, 13/91 (14%) developed de novo CKD, while CKD persisted or worsened in 49% (44/91). Etiology of heart failure, extracorporeal membrane oxygenation use, duration of CF-VAD, AKI history, and kidney replacement therapy were not associated with different CKD outcomes. Mortality was higher in those with AKI or preexisting CKD.

CONCLUSIONS

In the first multicenter study to focus on kidney outcomes for pediatric long-term CF-VAD patients, preimplantation CKD and peri-implantation AKI were common. Both de novo CKD and worsening CKD can happen on prolonged CF-VAD support. Proactive kidney function monitoring and targeted follow-up are important to optimize outcomes.

Cardiogenic shock and chronic kidney disease: Dangerous liaisons

BACKGROUND

Chronic kidney disease (CKD) is one of the leading causes of death worldwide, closely interrelated with cardiovascular diseases, ultimately leading to the failure of both organs - the so-called "cardiorenal syndrome". Despite this burden, data related to cardiogenic shock outcomes in CKD patients are scarce.

METHODS

FRENSHOCK (NCT02703038) was a prospective registry involving 772 patients with cardiogenic shock from 49 centres. One-year outcomes (rehospitalization, death, heart transplantation, ventricular assist device) were analysed according to history of CKD at admission and were adjusted on independent predictive factors.

RESULTS

CKD was present in 164 of 771 patients (21.3%) with cardiogenic shock; these patients were older (72.7 vs. 63.9years) and had more comorbidities than those without CKD. CKD was associated with a higher rate of all-cause mortality at 1month (36.6% vs. 23.2%; hazard ratio 1.39, 95% confidence interval 1.01-1.9; P=0.04) and 1year (62.8% vs. 40.5%, hazard ratio 1.39, 95% confidence interval 1.09-1.77; P<0.01). Patients with CKD were less likely to be treated with norepinephrine/epinephrine or undergo invasive ventilation or receive mechanical circulatory support, but were more likely to receive renal replacement therapy (RRT). RRT was associated with a higher risk of all-cause death at 1month and 1year regardless of baseline CKD status.

CONCLUSIONS

Cardiogenic shock and CKD are frequent "cross-talking" conditions with limited therapeutic options, resulting in higher rates of death at 1month and 1year. RRT is a strong predictor of death, regardless of preexisting CKD. Multidisciplinary teams involving cardiac and kidney physicians are required to provide integrated care for patients with failure of both organs.

Advanced Heart Failure: Therapeutic Options and Challenges in the Evolving Field of Left Ventricular Assist Devices

Heart Failure is a chronic and progressively deteriorating syndrome that has reached epidemic proportions worldwide. Improved outcomes have been achieved with novel drugs and devices. However, the number of patients refractory to conventional medical therapy is growing. These advanced heart failure patients suffer from severe symptoms and frequent hospitalizations and have a dismal prognosis, with a significant socioeconomic burden in health care systems. Patients in this group may be eligible for advanced heart failure therapies, including heart transplantation and chronic mechanical circulatory support with left ventricular assist devices (LVADs). Heart transplantation remains the treatment of choice for eligible candidates, but the number of transplants worldwide has reached a plateau and is limited by the shortage of donor organs and prolonged wait times. Therefore, LVADs have emerged as an effective and durable form of therapy, and they are currently being used as a bridge to heart transplant, destination lifetime therapy, and cardiac recovery in selected patients. Although this field is evolving rapidly, LVADs are not free of complications, making appropriate patient selection and management by experienced centers imperative for successful therapy. Here, we review current LVAD technology, indications for durable MCS therapy, and strategies for timely referral to advanced heart failure centers before irreversible end-organ abnormalities.

Improvement of persistent anuria in severe myocardial infarction: the potential role of Impella 5.5 as a bridge to decision

A man in his 40s with ST-segment elevation myocardial infarction complicating cardiogenic shock was transferred to our hospital. Emergent percutaneous coronary intervention for the left anterior descending and left circumflex arteries supported with Impella CP was performed. However, his cardiac function was severely impaired, and anuria developed, necessitating continuous renal replacement therapy (CRRT). After Impella CP was removed on day 6, the patient remained dependent on inotropes and CRRT. Following volume reduction to manage pulmonary congestion, symptoms of low perfusion appeared. Then, Impella 5.5 was inserted on day 38 as a bridge to decision. On day 52, the urine volume reached >2000 mL/day, and CRRT was discontinued. On day 56, the patient was transferred to a certified facility for left ventricular assist device implantation or heart transplantation. This case suggests the potential of Impella 5.5 as a bridge to decision in patients with organ failure caused by low cardiac output.

The impact of preoperative kidney replacement therapy on kidney outcome and survival in patients with left ventricular assist device

Left ventricular assist device (LVAD) has been highlighted as a new treatment option in the end-stage heart failure (HF). Kidney outcome after LVAD in severe cardiorenal syndrome (CRS) patients requiring kidney replacement therapy (KRT) is unclear. We investigated the impact of preoperative KRT on kidney function and survival in LVAD patients with severe CRS. A total of 50 patients followed up for at least 1 year after LVAD implantation was analyzed. The primary outcomes were estimated glomerular filtration rate and survival rate. Patients were divided into two groups depending on in-hospital KRT before LVAD implantation: the control group (n = 33) and the KRT group (n = 17). Postoperative KRT was performed for 76.5% of patients in the KRT group, and all of them discontinued KRT before discharge. There were no statistically significant differences in the degree of eGFR decline in survivors according to preoperative KRT. Although there were no statistically significant differences in the degree of eGFR decline in survivors regardless of preoperative KRT, old age (β -0.94, p < 0.01), preexisting chronic kidney disease (β -21.89, p < 0.01), and high serum creatinine (β -13.95, p < 0.01) were identified as independent predictors of post-LVAD eGFR decline. Mortality rate was higher, and more patients progressed to end-stage kidney disease in KRT group than control group. However, LVAD still can be considered as the treatment option in end-stage HF patients with severe CRS requiring KRT, especially in those with young age and previous normal kidney function.

Novel Estimates of Renal Function are Associated with Short-Term Left Ventricular Assist Device Outcomes

INTRODUCTION

Although preoperative kidney function has been associated with left ventricular assist device (LVAD) outcomes, most previous estimates of glomerular filtration rates (eGFRs) have utilized race in the calculation. Recently, novel eGFR equations independent of race have been suggested and validated. Therefore, we undertook this study to evaluate the predictive value of a novel, non-race-based eGFR calculation on short-term LVAD outcomes.

METHODS

We conducted a retrospective review of all primary LVAD implants from 2017 to 2022 at our institution. eGFR was calculated using the novel Chronic Kidney Disease Epidemiology Collaboration 2021 formula (CKD-EPI 2021). eGFR was also calculated according to the Modification of Diet in Renal Disease equation for historical reference. Primary stratification was by eGFR: ≥60, 30-60, and <30. The primary outcome was 1-y survival. Multivariable Cox proportional hazards regression modeling was used to further evaluate the impact of kidney function on 1-y mortality.

RESULTS

From 2017 to 2022, 91 patients underwent LVAD implantation with a HeartMate 3 device. The average age was 65.20 ± 11.08, 77 (84.62%) were male, and 14 (15.38%) were Black. The mean CKD-EPI 2021 eGFR was 56.07 ± 23.55 compared with 54.72 ± 26.37 as calculated by Modification of Diet in Renal Disease (P = 0.719). Overall, 30-d and 1-y survival was 96.7% and 85.0%, respectively. When stratified by eGFR, there was a significant difference in 1-y survival (≥60, 93.46%; 30-60, 87.36%; <30, 62.75%; P = 0.016). On multivariable analysis, a preoperative eGFR <30 was associated with an increased hazard of 1-y mortality (5.58 [1.06-29.17], P = 0.043).

CONCLUSIONS

In conclusion, non-race-based estimates of renal function are predictive of short-term LVAD outcomes. Further investigation of this phenomenon is warranted.

Long-Term Changes in Estimated Glomerular Filtration Rate in Left Ventricular Assist Device Recipients: A Longitudinal Joint Model Analysis

Background Advanced kidney disease is often a relative contraindication to left ventricular assist device (LVAD) implantation because of concerns for poor outcomes including worsening kidney disease. Data are lacking on long-term changes and sex-based differences in estimated glomerular filtration rate (eGFR), with published data limited by potential bias introduced by the competing risks of death and heart transplantation. Methods and Results We conducted a longitudinal analysis of 288 adults receiving durable continuous-flow LVADs from January 2010 to December 2017 at a single center. A joint model was constructed to evaluate change in eGFR over 2 years, the prespecified primary outcome, adjusted for the competing risks of death and heart transplantation. Median baseline eGFR was 60 mL/min per 1.73 m2 (interquartile range 42-78). At 2 years, 74 patients died and 104 received a heart transplant. In unadjusted analysis, LVAD recipients had a modest initial increase in eGFR of ≈2 mL/min per 1.73 m2 within the first 6 months after implantation, followed by a decrease in eGFR below baseline values at 1 and 2 years. Men experienced an eGFR decline of 5 to 10 mL/min per 1.73 m2 over the first year which then stabilized, while women had an ≈5 mL/min per 1.73 m2 increase in eGFR within the first 6 months followed by decline towards baseline eGFR levels (interaction P=0.005). Conclusions Estimated GFR remains relatively stable in most patients following LVAD implantation. Larger studies are needed to investigate sex-based differences in eGFR and to evaluate eGFR trajectory and mortality in LVAD recipients with lower eGFR.

Perioperative Management of the Patient at High-Risk for Cardiac Surgery-Associated Acute Kidney Injury

Acute kidney injury (AKI) is one of the most common major complications of cardiac surgery, and is associated with increased morbidity and mortality. Cardiac surgery-associated AKI has a complex, multifactorial etiology, including numerous factors such as primary cardiac dysfunction, hemodynamic derangements of cardiac surgery and cardiopulmonary bypass, and the possibility of a large volume of blood transfusion. There are no truly effective pharmacologic therapies for the management of AKI, and, therefore, anesthesiologists, intensivists, and cardiac surgeons must remain vigilant and attempt to minimize the risk of developing renal dysfunction. This narrative review describes the current state of the scientific literature concerning the specific aspects of cardiac surgery-associated AKI, and presents it in a chronological fashion to aid the perioperative clinician in their approach to this high-risk patient group. The evidence was considered for risk prediction models, preoperative optimization, and the intraoperative and postoperative management of cardiac surgery patients to improve renal outcomes.

Selection and management considerations to enhance outcomes in patients supported by left ventricular assist devices

PURPOSE OF REVIEW

Left ventricular assist devices (LVADs) are life-saving therapies for patients in end-stage heart failure (HF) with reduced ejection fraction regardless of candidacy for heart transplantation. Multiple clinical trials have demonstrated improved morbidity and mortality with LVADs when compared to medical therapy alone. However, the uptake of LVADs as a therapeutic option in a larger section of end-stage HF patients remains limited, partly due to associated adverse events and re-hospitalization.

RECENT FINDINGS

Accurate assessment and staging of HF patients is crucial to guide appropriate use of LVADs. Innovative methods to risk stratify patients and manage cardiac and noncardiac comorbidities can translate to improved outcomes in LVAD recipients. Inclusion of quality of life metrics and measurements of adverse events can better inform heart failure cardiologists to help identify ideal LVAD candidates. Addition of machine learning algorithms to this process may guide patient selection to improve outcomes.

SUMMARY

Patient selection and assessment of reversible medical comorbidities are critical to the postoperative success of LVAD implantation. Identifying patients most likely to benefit and least likely to experience adverse events should be a priority.

Outcomes in Patients with Chronic Kidney Disease and End Stage Renal Disease and Durable Left Ventricular Assist Device: Insights from United States Renal Data System Database

BACKGROUND

There is paucity of data regarding durable LVAD outcomes in patients with chronic kidney disease (CKD) stage 3-5 and CKD stage 5 on dialysis (ESRD: end stage renal disease).

METHODS

We conducted a retrospective study of Medicare beneficiaries with ESRD and 5% sample of CKD with LVAD (2006 to 2018) to determine one-year outcomes utilizing the United States Renal Data System (USRDS) database. The LVAD implantation, comorbidities and outcomes were identified using appropriate ICD-9 and ICD-10 codes.

RESULTS

We identified 496 CKD and 95 ESRD patients who underwent LVAD implantation. The ESRD patients were younger (59 vs 66 years; p <0.001), had more Blacks (40% vs 24.6%; p=0.009), compared to the CKD group. One-year mortality (49.5% vs 30.9%; p <0.001) and index mortality (27.4% vs 16.7%; p=0.014) was higher in ESRD. Subgroup analysis showed significantly higher mortality in ESRD vs CKD 3 (49.5% vs 30.2%, adjusted p=0.009), but no significant difference in mortality between stage 3 vs 4/5 (30.2% vs 30.8%; adjusted p=0.941). There was no significant difference in secondary outcomes (bleeding, stroke, and sepsis/infection) during follow-up between two groups.

CONCLUSIONS

Patients with ESRD undergoing LVAD implantation had significantly higher index and 1-year mortality compared to CKD patients.

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.

Mechanical Circulatory Support as a Bridge-to-Transplant Candidacy: When Does It Work?

Durable mechanical circulatory support (dMCS) devices can be offered as a bridge-to-transplant (BTT) or as a bridge-to-candidacy (BTC) strategy for candidates with contraindications to transplant listing, including pulmonary hypertension (BTC-PH), morbid obesity (BTC-Obes), social issues (BTC-Soc), or chronic illness (BTC-Illness). An understanding of the trajectory of BTC patients could guide future triage of advanced heart failure patients who are not candidates for transplantation. We performed a retrospective review all patients who underwent dMCS implantation as either BTT (206 patients) or BTC (114 patients) at our center from January 1, 2010, to March 31, 2020. There was no significant difference in mortality between BTC patients and BTT patients. Compared with the BTT group, significantly more patients in the BTC-PH group were transplanted (81% vs. 63%; p < 0.05) and significantly fewer patients in the BTC-Obes group (44%; p < 0.05) and BTC-Soc group (39%; p < 0.05) were transplanted. Additionally, the readmission rate was higher for those in the BTC-Obes (6.2 vs. 2.1; p < 0.05) and BTC-Soc (3.9 vs. 2.1; p < 0.05) groups. Bridge-to-candidacy patients generally had poorer post-dMCS trajectories than BTT patients. Centers should not be dissuaded from pursuing a BTC strategy for qualified patients; however, careful consideration of potential adverse outcomes is necessary.

Improvement of cardiac function after coronary artery bypass grafting surgery reduces the risk of postoperative acute kidney injury

Background

Pre‐existing renal dysfunction is an independent risk factor for cardiac surgery‐associated acute kidney injury (AKI). We aimed to investigate whether the improvement of postoperative cardiac function after coronary artery bypass grafting (CABG) surgery would affect the risk of AKI in patients with different levels of baseline renal function.

Methods

Data were collected from patients who underwent CABG surgery from January 2018 to April 2019. Patients were divided into normal (GFR ≥ 90 ml/min/1.73 m²), non‐CKD (60≤GFR < 90 ml/min/1.73 m²), and CKD (GFR < 60 ml/min/1.73 m²) groups. Improvement in cardiac function was defined as △LVEF (postoperative LVEF–preoperative LVEF) ≥ 10% preoperative LVEF. Patients were further divided into subgroups according to postoperative cardiac function improvement.

Results

A total of 1365 patients were enrolled, including 793 (58.1%) in the normal group, 476 (34.9%) in the non‐CKD group, and 96 (7.0%) in the CKD group. The AKI incidence in the normal, non‐CKD, and CKD groups was 22.2%, 28.4%, and 40.6%, respectively. Patients with improved cardiac function in the non‐CKD and CKD groups had significantly lower AKI incidence than those without improved cardiac function (22.8% vs. 36.9%, p = .002% and 32.8% vs. 54.3%, p = .037, respectively). For non‐CKD patients with improved cardiac function, the serum creatinine at discharge was significantly lower than its preoperative serum creatinine (0.8 ± 0.5 vs 1.2 ± 0.9 mg/dl, p = .002). Multivariate logistic regression analysis showed that the improvement in cardiac function could reduce the risk for postoperative AKI in non‐CKD patients but not in CKD patients.

Conclusions

For patients with renal dysfunction and mildly reduced eGFR (60≤GFR < 90 ml/min/1.73 m²), improved cardiac function after CABG surgery can reduce the serum creatinine level and reduce the risk for postoperative AKI.

Outcome of Temporary Circulatory Support As a Bridge-to-Left Ventricular Assist Device Strategy in Cardiogenic Shock Patients

OBJECTIVES

Temporary circulatory support (TCS) as a bridge-to-left ventricular assist device (BTL) in cardiogenic shock patients has been increasing, but limited data exists on this BTL strategy. We aimed at analyzing the outcome of BTL patients in a population of cardiogenic shock patients compared with those without TCS at the time of the left ventricular assist device (LVAD) surgery and identify predictors of postoperative mortality in this specific population.

DESIGN

A multicenter retrospective observational study conducted in 19 centers from 2006 to 2016.

SETTING

Nineteen French centers.

PATIENTS

A total of 329 cardiogenic shock patients at the time of LVAD implantation were analyzed. Patients were divided in three groups: those under TCS at the time of LVAD implantation (n = 173), those with TCS removal before LVAD surgery (n = 24), and those who did not undergo a bridging strategy (n = 152). Primary endpoint was 30-day mortality.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Among the BTL group, 68 (39.3%), 18 (10.4%), and 15 (8.7%) patients were under venoarterial extracorporeal membrane oxygenation, Impella, and IABP support alone, and 72 patients (20.6%) were under multiple TCS support. BTL patients presented similar 30 days survival compared with the TCS removal and non-BTL groups. However, BTL group had a significantly longer ICU duration stay, with two-fold duration of mechanical ventilation time, but the three groups experienced similar postoperative complications. Multivariate analysis identified three independent predictors of mortality in the BTL group: combined surgery with LVAD, body mass index (BMI), and heart failure (HF) duration. BTL strategy was not an independent predictor of mortality in cardiogenic shock patients who underwent LVAD.

CONCLUSIONS

BTL strategy is not associated with a lower survival among cardiogenic shock patients with LVAD implantation. Predictors of mortality are combined surgery with LVAD, higher BMI, and HF duration.

The influence of preoperative dialysis on survival after continuous-flow left ventricular assist device implantation

 

OBJECTIVES

Dialysis is considered a contraindication to continuous-flow left ventricular assist device (CF-LVAD) implantation. We evaluated clinical outcomes and survival in carefully selected, low-risk patients with renal failure who required dialysis before CF-LVAD implantation.

METHODS

We extracted medical record data of patients who underwent CF-LVAD placement at our centre between 1 January 2006 and 31 August 2017, with 2 clinical scenarios: those who required long-term (>14 days) dialysis and those who required short-term (≤14 days) dialysis immediately before implantation. Demographic, clinical and intraoperative characteristics and survival outcomes were assessed.

RESULTS

Of 621 patients who underwent CF-LVAD implantation during the study period, 31 underwent dialysis beforehand. Of these, 17 required long-term dialysis (13 haemodialysis, 4 peritoneal dialysis), and 14 underwent short-term haemodialysis. Compared with the long-term dialysis patients, the short-term dialysis patients were more likely to be Interagency Registry for Mechanically Assisted Circulatory Support profile 1–2 (92.9% vs 70.6%; P < 0.001), to have needed preoperative mechanical circulatory support (78.6% vs 70.6%; P < 0.01) and to have higher in-hospital mortality (85.7% vs 29.4%; P = 0.01). Patients stable on long-term dialysis had acceptable overall survival and markedly better 6-month and 1-year survival than those with short-term dialysis before implantation (64.7% vs 14.3% and 58.8% vs 7.1%, respectively; P < 0.001).

CONCLUSIONS

Carefully selected patients who are stable on long-term dialysis have acceptable survival rates after CF-LVAD implantation. Patients with acute renal failure had much poorer outcomes than those with chronic end-stage renal disease.

Physiology of Continuous-Flow Left Ventricular Assist Device Therapy

The expanding use of continuous-flow left ventricular assist devices (CF-LVADs) for end-stage heart failure warrants familiarity with the physiologic interaction of the device with the native circulation. Contemporary devices utilize predominantly centrifugal flow and, to a lesser extent, axial flow rotors that vary with respect to their intrinsic flow characteristics. Flow can be manipulated with adjustments to preload and afterload as in the native heart, and ascertainment of the predicted effects is provided by differential pressure-flow (H-Q) curves or loops. Valvular heart disease, especially aortic regurgitation, may significantly affect adequacy of mechanical support. In contrast, atrioventricular and ventriculoventricular timing is of less certain significance. Although beneficial effects of device therapy are typically seen due to enhanced distal perfusion, unloading of the left ventricle and atrium, and amelioration of secondary pulmonary hypertension, negative effects of CF-LVAD therapy on right ventricular filling and function, through right-sided loading and septal interaction, can make optimization challenging. Additionally, a lack of pulsatile energy provided by CF-LVAD therapy has physiologic consequences for end-organ function and may be responsible for a series of adverse effects. Rheological effects of intravascular pumps, especially shear stress exposure, result in platelet activation and hemolysis, which may result in both thrombotic and hemorrhagic consequences. Development of novel solutions for untoward device-circulatory interactions will facilitate hemodynamic support while mitigating adverse events. © 2021 American Physiological Society. Compr Physiol 12:1-37, 2021.

Heart, kidney and left ventricular assist device: a complex trio

BACKGROUND

Heart failure (HF) is a complex syndrome affecting the whole body, kidneys included. The left ventricular assist device (LVAD) is a valid option for patients with very severe HF. Focusing on renal function, LVAD implantation could theoretically reverse the detrimental effects of HF syndrome on kidneys. However, implanting an LVAD is a high-risk surgical procedure, and LVAD patients have higher risk of bleeding, device thrombosis, strokes, renal impairment, multi-organ failure and infections. Furthermore, an LVAD has its own particular effects on the renal system.

METHODS

In this review, we provide a comprehensive overview of the complex interaction between LVAD and the kidneys from the pathophysiological and clinical perspectives. An analysis of the different effects of pulsatile-flow and continuous-flow LVAD is provided.

RESULTS

Despite their limitations, creatinine-based estimated glomerular filtration rate (eGFR) formulas help to stratify patients by their post-LVAD placement prognosis. Poor basal renal function, the onset of acute kidney injury or the need for renal replacement therapy after LVAD implantation negatively influences a patient's prognosis. LVAD can also prompt an improvement in renal function, however, with some counterintuitive effects on a patient's prognosis.

CONCLUSION

It is still hard to say whether different trends in eGFR depend on different renal conditions before LVAD placement, on a patient's better overall status or on a particular patient management strategy before and/or after the device's implantation. Steps should be taken to solve this question because finding the best candidates for LVAD implantation is of paramount importance to ensure the best outcomes.

Hemodynamic Predictors of Renal Function After Pediatric Left Ventricular Assist Device Implantation

Although renal function often improves after pediatric left ventricular assist device (LVAD) implantation, recovery is inconsistent. We aimed to identify hemodynamic parameters associated with improved renal function after pediatric LVAD placement. A single-center retrospective cohort study was conducted in patients less than 21 years who underwent LVAD placement between June 2004 and December 2015. The relationship between hemodynamic parameters and estimated glomerular filtration rate (eGFR) was assessed using univariate and multivariate modeling. Among 54 patients, higher preoperative central venous pressure (CVP) was associated with eGFR improvement after implantation (p = 0.012). However, 48 hours postimplantation, an increase in CVP from baseline was associated with eGFR decline over time (p = 0.01). In subgroup analysis, these associations were significant only for those with normal pre-ventricular assist device renal function (p = 0.026). In patients with preexisting renal dysfunction, higher absolute CVP values 48 and 72 hours after implantation predicted better renal outcome (p = 0.005). Our results illustrate a complex relationship between ventricular function, volume status, and renal function. Additionally, they highlight the challenge of using CVP to guide management of renal dysfunction in pediatric heart failure. Better methods for evaluating right heart function and volume status are needed to improve our understanding of how hemodynamics impact renal function in this population.

Oxidative Stress Markers and Modified Model for End-Stage Liver Disease Are Associated with Outcomes in Patients with Advanced Heart Failure Receiving Bridged Therapy with Continuous-Flow Left Ventricular Assist Devices

Left ventricular assist device (LVAD) is well established as an alternative treatment for end-stage heart failure (HF) patients. The aim of the study was to determine the prognostic value of oxidative stress markers and the modified Model for End-Stage Liver Disease (modMELD) in patients receiving bridged therapy with continuous-flow LVAD. We prospectively analyzed 36 end-stage HF patients who received LVAD therapy between 2015 and 2018. The total antioxidant capacity (TAC) and total oxidant status (TOS) were measured by the methods described by Erel. The oxidative stress index (OSI) was defined as the ratio of the TOS to TAC levels. The modMELD scores were calculated based on the serum bilirubin, creatinine, and albumin levels. The patients’ median age was 58 (50–63.0) years. During the 1.5-years follow-up, a major adverse cardiac event—MACE (death, stroke, or pump thrombosis) was observed in 17 patients (47.2%). The area under the receiver operating characteristics curves (AUCs) indicated a good prognostic power of TAC (AUC 0.7183 (0.5417–0.8948)), TOS (AUC 0.9149 (0.8205–0.9298)), OSI (AUC 0.9628 (0.9030–0.9821)), and modMELD (AUC 0.87 (0.7494–0.9905)) to predict a MACE. Oxidative stress markers serum concentrations, as well as the modMELD score, allow the identification of patients with a risk of MACE.

Long-Term renal function after implantation of continuous-flow left ventricular assist devices: A single center study

Background

Implantable continuous-flow left ventricular assist device (LVAD) improve renal function in advanced heart failure. However, the long-term effects of LVAD on renal function have not been investigated thoroughly. We aimed to assess long-term renal function in patients with LVAD support and to identify predictors for late deterioration in renal function (LDRF).

Methods

One hundred patients underwent LVAD implantation as a bridge to transplant at the University of Tokyo Hospital between May 2011 and December 2018. We assessed renal function at intervals (preoperative, 1, 6, 12, 18, 24 and 30 months after LVAD implantation). We divided patients into two groups: “with LDRF,” whose renal function at 30 months had decreased by >25% compared with preoperatively (n = 14), and “without LDRF” (n = 55).

Results

Renal function improved at 1 month, returned to preoperative levels at 6 months, and remained there up to 30 months after LVAD implantation. However, renal function impairment became evident in patients with LDRF 18 months after LVAD implantation. A ratio of right atrial pressure/pulmonary artery wedge pressure > 0.57 and left ventricular dimension diastole ≤ 67 mm were preoperative independent risk factors for LDRF. In addition, the incidence of perioperative acute kidney injury, ventricular arrhythmia, aortic insufficiency, and late right ventricular failure was significantly higher in patients with LDRF.

Conclusion

LDRF after LVAD implantation corresponded to several risk factors, including a small left ventricle and LVAD-related complications, such as right ventricular failure.

Change in Renal Function and Its Impact on Survival in Chronic Kidney Disease Patients Bridged to Heart Transplantation With a Left Ventricular Assist Device

The study investigates the incidence of change in renal function and its impact on survival in renal dysfunction patients who were bridged to heart transplantation with a left ventricular assist device (BTT-LVAD). BTT-LVAD patients with greater than or equal to moderately reduced renal function (estimated glomerular filtration rate [eGFR] ≤ 60 ml/min/1.73 m2) at the time of listing between 2008 and 2018 were identified from a prospectively maintained database of the United Network for Organ Sharing. Patients with a baseline eGFR less than or equal to 15 ml/min/1.73 m2 or on dialysis were excluded. Patients were divided into three groups based on percent change ([Pretransplant eGFR - listing eGFR/listing glomerular filtration rate (GFR)] × 100) in eGFR: Improvement greater than or equal to 10%, no change, decline greater than or equal to 10%, and their operative outcomes were compared. Posttransplant survival was estimated and compared among the three groups with the Kaplan-Meier survival curves and the log-rank test. Cox proportional hazards modeling was used to identify predictors of posttransplant survival. Out of 14,395 LVAD patients, 1,622 (11%) met the inclusion criteria. At the time of transplant, 900 (55%) had reported an improvement in eGFR greater than or equal to 10%, 436 (27%) had no change, and 286 (18%) experienced a decline greater than or equal to 10%. Postoperatively, the incidence of dialysis was higher in the decline than in the unchanged or improved groups (22% vs. 12% vs. 12%; p = 0.002). After a median follow-up of 5 years, there was no difference in posttransplant survival among the stratified groups (improved eGFR: 24.8%, unchanged eGFR: 23.2%, declined eGFR: 20.3%; p = 0.680). On Cox proportional hazard modeling, independent predictors of worse survival were: [hazard ratio: 95% CI; p] history of diabetes (1.43 [1.13-1.81]; p = 0.002) or tobacco use (1.40 [1.11-1.79]; p = 0.005) and ischemic time greater than 4 hours (1.36 [1.03-1.76]; p = 0.027). More than half of the patients with compromised renal function who undergo BTT-LVAD demonstrate an improvement in renal function at the time of transplant. A 10% change in GFR while listed was not associated with worse posttransplant survival.

Kidney Function Following Left Ventricular Assist Device Implantation: An Observational Cohort Study

Rationale & Objective

Nearly half the patients with heart failure have chronic kidney disease. Implantation of a left ventricular assist device (LVAD) improves kidney function in some but not all patients, and lack of improvement is associated with worse outcomes. Preimplantation factors that predict change in kidney function after LVAD placement are not well described.

Study Design

Single-center observational study.

Setting & Participants

Consecutive patients undergoing LVAD implantation.

Predictors

48 diverse preimplantation variables including demographic, clinical, laboratory, hemodynamic, and echocardiographic variables.

Outcomes

The primary outcome was change in estimated glomerular filtration rate (eGFR) at 1 month after implantation. Secondary outcomes included eGFR changes at 3, 6, and 12 months.

Analytic Approach

Univariable and multivariable linear regression.

Results

Among 131 patients, average age was 60 ± 13 years, 83% were men, 47% had pre-existing chronic kidney disease, and mean preimplantation eGFR was 57 ± 23 mL/min/1.73 m². At 1-month following LVAD implantation, eGFR improved in 98 (75%) patients. Variables associated with 1-month increases in eGFR were younger age, absence of diabetes mellitus (DM), use of inotropes, lower implantation eGFR, and higher implantation serum urea nitrogen, alanine aminotransferase, bilirubin, and creatinine levels. In multivariable models, younger age (β = 7.14 mL/min/1.73 m² per SD; 95% CI, 3.17-11.10), lower eGFR (β = 7.72 mL/min/1.73 m² per SD; 95% CI, 3.10-12.34), and absence of DM (β = 10.36 mL/min/1.73 m²; 95% CI, 2.99-17.74) were each independently associated with 1-month improvement in eGFR. Only younger age and lower eGFR were associated with improvements in eGFR at later months.

Limitations

Single-center study. Loss to follow-up from heart transplantation and death over duration of study.

Conclusions

Only younger age, lower eGFR, and absence of DM were associated with improvement in eGFR at 1 month. Thus, prediction of eGFR change at 1 month and beyond is limited by using preimplantation variables.

Predictors of renal replacement therapy in patients with continuous flow left ventricular assist devices

Renal replacement therapy (RRT) after continuous flow left ventricular assist device (CF-LVAD) implantation significantly affects patients' quality of life and survival. To identify preoperative prognostic markers in patients requiring RRT after CF-LVAD implantation, we retrospectively reviewed data from patients who underwent implantation of a CF-LVAD at our institution during 2012-2017. Patients who required preoperative RRT were excluded. Preoperative and operative characteristics, as well as survival and adverse events, were compared between 74 (22.2%) patients requiring any duration of postoperative RRT and 259 (77.8%) not requiring RRT. Patients requiring RRT experienced more postoperative complications than patients who did not, including respiratory failure necessitating tracheostomy (35.7% vs 2.5%, p < 0.001), reoperation for bleeding (34.3% vs 11.7%, p < 0.001), and right heart failure necessitating perioperative mechanical circulatory support (32.4% vs 6.9%, p < 0.001). Patients requiring postoperative RRT also had poorer survival at 30 days (74.7% vs 98.8%), 6 months (48.2% vs 95.1%), and 12 months (45.3% vs 90.2%) (p < 0.001). Significant predictors of RRT after CF-LVAD implantation included urine proteinuria (odds ratio [OR] 3.6, 95% confidence interval [CI] [1.7-7.6], p = 0.001), estimated glomerular filtration rate < 45 mL/min/1.73 m² (OR 3.4, 95% CI [1.5-17.8], p = 0.004), and mean right atrial pressure to pulmonary capillary wedge pressure ratio ≥ 0.54 (OR 2.6, 95% CI [1.3-5.], p = 0.01). Of the 74 RRT patients, 11 (14.9%) recovered renal function before discharge, 36 (48.6%) still required RRT after discharge, and 27 (36.5%) died before discharge. We conclude that preoperative renal and right ventricular dysfunction significantly predict postoperative renal failure and mortality after CF-LVAD implantation.

Ventricular Assist Devices and Chronic Kidney Replacement Therapy: Technology and Outcomes

Heart failure and kidney failure are very common conditions, precipitating and exacerbating each other. Left ventricular assist devices (LVADs) represent a relatively new technology for treatment of advanced heart failure. Kidney dysfunction, if present, makes candidate selection for LVADs challenging and contributes to multiple complications while the patients are on an LVAD support. Although kidney function generally improves after LVAD implantation, some patients develop acute and then chronic kidney disease sometimes requiring kidney replacement therapies (KRTs). Overall, chronic KRT in LVAD recipients is feasible and well tolerated, but routine technique of blood pressure monitoring should be adjusted to the continuous blood flow. Both hemodialysis and peritoneal dialysis can be used. Unique challenges for chronic KRT posed by the presence of LVAD are discussed in this review.

Congestive nephropathy: a neglected entity? Proposal for diagnostic criteria and future perspectives

Venous congestion has emerged as an important cause of renal dysfunction in patients with cardiorenal syndrome. However, only limited progress has been made in differentiating this haemodynamic phenotype of renal dysfunction, because of a significant overlap with pre-existing renal impairment due to long-term hypertension, diabetes, and renovascular disease. We propose congestive nephropathy (CN) as this neglected clinical entity. CN is a potentially reversible subtype of renal dysfunction associated with declining renal venous outflow and progressively increasing renal interstitial pressure. Venous congestion may lead to a vicious cycle of hormonal activation, increased intra-abdominal pressure, excessive renal tubular sodium reabsorption, and volume overload, leading to further right ventricular (RV) stress. Ultimately, renal replacement therapy may be required to relieve diuretic-resistant congestion. Effective decongestion could preserve or improve renal function. Congestive acute kidney injury may not be associated with cellular damage, and complete renal function restoration may be a confirmatory diagnostic criterion. In contrast, a persistently low renal perfusion pressure might induce renal dysfunction and histopathological lesions with time. Thus, urinary markers may differ. CN is mostly seen in biventricular heart failure but may also occur secondary to pulmonary arterial hypertension and elevated intra-abdominal pressure. An increase in central venous pressure to >6 mmHg is associated with a steep decrease in glomerular filtration rate. However, the central venous pressure range that can provide an optimal balance of RV and renal function remains to be determined. We propose criteria to identify cardiorenal syndrome subgroups likely to benefit from decongestive or pulmonary hypertension-specific therapies and suggest areas for future research.

Impact of bridge-to-bridge strategies from paracorporeal to implantable left ventricular assist devices on the pre-heart transplant outcome: A single-center analysis of 134 cases

BACKGROUND

In Japan, patients with heart failure who have a paracorporeal left ventricular assist device (pLVAD) and cannot be weaned from the VAD may undergo conversion to implantable continuous-flow LVAD (iLVAD) via a bridge-to-bridge (BTB) strategy for bridge-to-transplantation (BTT). This study aimed to evaluate the real-world clinical status of BTB strategies.

METHODS

Among 134 patients who underwent iLVAD implantation for BTT, 34 patients underwent conversion from pLVAD to iLVAD (BTB group) and 100 patients underwent iLVAD implantation primarily (primary iLVAD group). The clinical characteristics and outcomes were compared between the two groups.

RESULTS

No significant difference was found in the overall survival between the two groups (p = 0.26; log-rank test). However, the 1-year survival rate and the 1-year freedom from the composite events of death, stroke, systemic infection, and bleeding rate were lower in the BTB group than in the primary iLVAD group (survival rate, 88.2% vs. 99.0%, p = 0.0040; composite event-free survival rate, 26.1% vs. 49.8%, p = 0.030; log-rank test). Multivariate analysis indicated that the BTB strategy [hazard ratio (HR) 1.70, 95% confidence intervals (CI) 1.03-2.72; p=0.036] and serum total bilirubin levels at iLVAD implantation [HR 1.31, 95% CI 1.00-1.65; p=0.043] were independent predictors of 1-year composite events.

CONCLUSIONS

The BTB strategy is useful in providing long-term survival in patients with acute critical diseases. However, the early mortality rate after conversion is higher in patients who underwent the BTB strategy.

Improvement in Kidney Function After Ventricular Assist Device Implantation and Its Influence on Thromboembolism, Hemorrhage, and Mortality

Although heart transplantation remains the gold standard for management of heart failure, ventricular assist devices (VAD) have emerged as viable alternatives. VAD implantation improves kidney function. However, whether the improvement is sustained or associated with improved outcomes is unclear. Herein we assess kidney function improvement, predictors of improvement, and associations with thromboembolism, hemorrhage, and mortality in VAD patients. Kidney function was defined using chronic kidney disease (CKD) stages: stage 1 (glomerular filtration rate [eGFR] ≥ 90 ml/min/1.73 m), stage 2 (eGFR 60-90 ml/min/1.73 m), stage 3a (eGFR 45-59 ml/min/1.73 m), stage 3b (eGFR 30-44 ml/min/1.73 m), stage 4 (eGFR 15-30 ml/min/1.73 m), and stage 5 (eGFR < 15 ml/min/1.73 m). Improvement in kidney function was defined as an improvement in eGFR that resulted in a CKD stage change to one of lesser severity. Kidney function improved post implant, and was maintained over 1 year for all patients, except those with baseline stage 5 CKD. Younger age at implantation (OR 0.93, 95% CI: 0.90-0.96, P < 0.0001) was associated with sustained improvement in kidney function. Poor kidney function was associated increased mortality but not with thromboembolism or hemorrhage. Compared to patients with baseline eGFR > 45 ml/min/1.73 m; patients with eGFR < 45 ml/min/1.73 m had a higher mortality risk (HR 3.32, 95% CI: 1.10-9.98, p = 0.03 for stage 3b; HR 4.07, 95% CI: 1.27-13.1, p = 0.02 for stage 4; and HR 4.01, 95% CI: 1.17-13.7, p = 0.03 for stage 5 CKD). Kidney function was not associated with thromboembolism or hemorrhage, and sustained improvement was not associated with lower risk of death. However, poor kidney function at implantation was associated with an increased risk of mortality.

Incidence and impact of acute kidney injury on patients with implantable left ventricular assist devices: a Meta-analysis

Background: We aimed to evaluate the acute kidney injury (AKI) incidence and its associated risk of mortality in patients with implantable left ventricular assist devices (LVAD).Methods: A systematic literature search in Ovid MEDLINE, EMBASE, and Cochrane Databases was conducted through January 2020 to identify studies that provided data on the AKI incidence and AKI-associated mortality risk in adult patients with implantable LVADs. Pooled effect estimates were examined using random-effects, generic inverse variance method of DerSimonian-Laird.Results: Fifty-six cohort studies with 63,663 LVAD patients were enrolled in this meta-analysis. The pooled incidence of reported AKI was 24.9% (95%CI: 20.1%-30.4%) but rose to 36.9% (95%CI: 31.1%-43.1%) when applying the standard definition of AKI per RIFLE, AKIN, and KDIGO criteria. The pooled incidence of severe AKI requiring renal replacement therapy (RRT) was 12.6% (95%CI: 10.5%-15.0%). AKI incidence did not differ significantly between types of LVAD (p = .35) or indication for LVAD use (p = .62). While meta-regression analysis did not demonstrate a significant association between study year and overall AKI incidence (p = .55), the study year was negatively correlated with the incidence of severe AKI requiring RRT (slope = -0.068, p < .001). The pooled odds ratios (ORs) of mortality at 30 days and one year in AKI patients were 3.66 (95% CI, 2.00-6.70) and 2.22 (95% CI, 1.62-3.04), respectively. The pooled ORs of mortality at 30 days and one year in severe AKI patients requiring RRT were 7.52 (95% CI, 4.58-12.33) and 5.41 (95% CI, 3.63-8.06), respectively.Conclusion: We found that more than one-third of LVAD patients develop AKI based on standard definitions, and 13% develop severe AKI requiring RRT. There has been a potential improvement in the incidence of severe AKI requiring RRT for LVAD patients. AKI in LVAD patients was associated with increased 30-day and 1 year mortality.

Post-operative renal failure management in mechanical circulatory support patients

Acute kidney injury (AKI) occurs commonly in patients requiring mechanical circulatory support (MCS) after cardiothoracic surgery. The prognostic implications of AKI in this patient group relate closely to the pathophysiology and risk factors associated with the underlying disease; pre-operative, intra-operative, and post-operative variables; hemodynamic factors; and type of support device used. General approaches to AKI management, including prevention strategies, medical management, and hemodynamic support, are also applicable in patients requiring MCS. Approaches to renal replacement therapy vary depend on patient factors, device-specific factors, and local preferences and experience. In this invited narrative review, we discuss the pathophysiology, risk factors, and prognostic implications of AKI in post-operative adult patients following institution of MCS. Management strategies for AKI are presented with a focus on those supported with either extracorporeal membrane oxygenation or a ventricular assist device.

Outcomes Among Patients With Left Ventricular Assist Devices Receiving Maintenance Outpatient Hemodialysis: A Case Series

RATIONALE & OBJECTIVE

The incidence of left ventricular assist device (LVAD) implantation as destination therapy for heart failure is increasing and kidney failure requiring maintenance hemodialysis is a common complication. Because little is known about the safety or efficacy of outpatient hemodialysis among patients with LVADs, this study sought to describe their clinical course.

STUDY DESIGN

Case series of patients with an LVAD undergoing maintenance outpatient hemodialysis whose clinical data were obtained from an electronic medical record.

SETTING & PARTICIPANTS

Adults who received an LVAD, survived to hospital discharge, and were subsequently treated with maintenance hemodialysis by a not-for-profit dialysis provider between 2011 and 2019.

RESULTS

11 patients were included. 6 had a known history of chronic kidney disease. Patients underwent outpatient hemodialysis for a mean duration of 165.2 (range, 31-542) days, during which they were treated with 544 total dialysis sessions. 6 of these sessions were stopped early due to dialysis-related adverse events (1.1%). More than 80% of follow-up time was spent out of the hospital; however, 55% of patients were rehospitalized within 1 month of starting outpatient hemodialysis. The most common reason for hospitalization was infection (32%), followed by hypervolemia (14%), and cerebrovascular accident or transient ischemic attack (11%). 4 patients recovered kidney function, 1 underwent combined heart and kidney transplantation, 2 continued treatment, 2 died, and 2 were lost to follow-up.

LIMITATIONS

Retrospective design, small number of cases, and lack of complete follow-up data.

CONCLUSIONS

Approximately half the patients with complete follow-up either recovered kidney function or underwent combined heart and kidney transplantation. This case series demonstrates that outpatient hemodialysis centers, in partnership with LVAD treatment teams, can successfully provide hemodialysis to patients on LVAD support.

Impaired Baseline Renal Function May Not Influence Outcomes and Survival After Left Ventricular Assist Device Implantation

BACKGROUND

We investigated changes in estimated glomerular filtration rate (eGFR) after left ventricular assist device (LVAD) implant and the impact on long-term outcomes.

METHODS

A retrospective analysis was conducted for 255 patients with LVADs, divided into 2 groups based on preimplant eGFR (<60 or >60 mL/min/1.73 m²) and into 6 grades (grade 1, >90 mL/min/1.73 m² normal; grade 2, 60-89 mild dysfunction; grade 3, 45-59 moderate; grade 4, 30-44 moderate to severe; grade 5, 15-29 severe; or grade 6, <15 kidney failure). Changes in eGFR and the impact on long-term outcome and survival were analyzed.

RESULTS

One-month postimplant eGFR of the total cohort increased from a baseline of 75.19 ± 34.35 to 118.97 ± 67.62 mL/min/1.73 m²(P < .001). eGRF 4 years postimplant was higher than baseline but not significantly (P = .48). Patients with a preimplant eGFR > 60 followed the same pattern as the entire cohort. The preimplant eGFR < 60 group had a significant increase at 1 month (P < .001), eGFR remained significantly higher than baseline 4 years postimplant (P = .032), and there was a sustained transition to improved distribution of renal function grade after LVAD implant. Post-LVAD implant survival at 1, 3, and 5 years for baseline eGFR > 60 was 76%, 54%, and 48% and for eGFR < 60 was 71%, 60%, and 48%, respectively (P = .92).

CONCLUSIONS

Patients with a low preimplant eGFR derive benefit from LVAD therapy, with eGFR remaining elevated above preimplant levels. Preimplant renal dysfunction did not impact negatively on long-term morbidity and mortality.

Kidney transplantation and cardiomyopathy: Concepts and controversies in clinical decision-making

Increasing comorbidities and an aging population have led to a tremendous increase in the burden of both kidney and cardiac dysfunction. Concomitant cardiomyopathy exposes the patients with kidney disease to further physiological, hemodynamic, and pathologic alterations. Kidney transplantation imposes lesser anesthetic and surgical complexities compared to another solid organ transplant. The surgical decision-making remains an unsettled issue in these conditions. The surgical choices, techniques, and sequences in kidney transplant and cardiac surgery depend on the pathophysiological perturbations and perioperative outcomes. The absence of randomized controlled trials eludes us from suggesting definite management protocol in patients with end-stage kidney disease with cardiomyopathy. Nevertheless, in this review, we extracted data from published literature to understand the pathophysiologic interactions between end-stage renal diseases with cardiomyopathy and also proposed the management algorithm in this challenging scenario. The proposed management algorithm would ensure consensus across all stakeholders involved in decision-making. Our simplistic evidence-based approach would augur future randomized trials and would further ensure refinement in our management approach after the emergence of more definitive evidence.

Comparison of Renal Outcomes in Patients With Left Ventricular Assist Device and Heart Transplantation

BACKGROUND

Renal function is a major consideration for orthotopic heart transplantation (OHT) and left ventricular assist device (LVAD) therapy. We compared serial changes in renal function and outcomes between patients who underwent OHT and LVAD therapy over 12 months.

METHODS

Forty-five and 58 consecutive patients who underwent LVAD implantation (all bridge to transplant or candidacy) and OHT from April 2014 to November 2016 were included. Six of these patients were in both LVAD and OHT cohorts. Survival analysis was calculated using Kaplan Meier and log rank methods. Univariate analysis of data was performed using χ², Mann-Whitney, Kruskal-Wallis, and Wilcoxon signed rank tests where appropriate. Comparisons of the renal function to baseline were conducted using generalized estimating equations.

RESULTS

Renal function had a biphasic course among the LVAD cohort, increasing at 30 days but reducing at 6 and 12 months. Meanwhile, estimated glomerular filtration rate (eGFR) was seen to progressively decline among OHT recipients. Altogether, eGFR was significantly higher at 6 and 12 months among the LVAD cohort compared to OHT (68.3 vs 59.4, P = .046; 68.3 vs 50.4, P = .015). Compared to the baseline average, eGFR had risen among the LVAD patients (P = .031) but had decreased among the OHT group (P < .001) at 12 months. No significant difference in survival was seen at 1 year (84.4% vs 81.0%; P = .540) and 2 years (78.3% vs 78.8%, P = .687) between the cohorts.

CONCLUSION

Despite poorer baseline renal function, LVAD therapy was associated with comparable survival and better renal outcomes compared to OHT at 12 months. Renal impairment may favor the use of LVAD therapy over OHT in the short term.

Durable left ventricular assist device support as a bridge to heart transplant candidacy†

OBJECTIVES

Left ventricular assist devices are funded in the UK exclusively as a bridge to transplant (BTT). However, patients who potentially could receive a transplant may develop reversible contraindications to transplant. Bridge to candidacy (BTC) has sometimes been controversial, given the uncertain clinical efficacy of BTC and the risk that reimbursement could be denied. We analysed the UK ventricular assist device database to understand how common BTC was and to assess patient survival rates and incidences of transplants.

METHODS

We identified BTC implants in patients with pulmonary hypertension, chronic kidney disease and obesity using the UK guidelines for heart transplants.

RESULTS

A total of 306 of 540 patients had complete data and 157 were identified as BTC (51%). Overall, there was no difference in survival rates between patients designated as BTC and those designated at BTT (71.9 vs 72.9% at 1 year, respectively; P = 0.82). However, the survival rate was lower at all time points in those with an estimated glomerular filtration rate (eGFR) <40 and in patients with a body mass index (BMI) >32 up to 1-year postimplant. There were no significant differences in the incidence of transplant between patients who were BTC and BTT or for any subgroup up to 5 years. However, we noted a diverging trend towards a lower cumulative incidence of transplant for patients with a BMI >32.

CONCLUSIONS

BTC is common in the UK and appears clinically effective, given that the survival rates and the incidence of transplants were comparable with those for BTT. Patients with a high BMI have a worse survival rate through to 1 year and a trend for a lower incidence of a transplant. Patients with a low eGFR also have a worse survival rate, but a similar proportion received transplants.

Maturation of arteriovenous fistulas in patients with ventricular assist devices

OBJECTIVE

Postoperative renal dysfunction necessitating hemodialysis after implantation of ventricular assist devices presents a challenge with respect to establishment of hemodialysis access. Lack of pulsatile flow has led to concerns that arteriovenous fistulas will not mature. This study aims to evaluate arteriovenous fistula as a method of hemodialysis.

METHODS

Consecutive patients who underwent implantation of a ventricular assist device between 1988 and 2016 with a subsequent need for hemodialysis were identified. Retrospective data were collected for patients requiring hemodialysis through an arteriovenous fistula or arteriovenous graft. Access flow rates and duration of patency are reported.

RESULTS

Sixty-four patients were identified (10 required long-term hemodialysis, 5 via arteriovenous fistula, 1 via arteriovenous graft). All six patients receiving long-term hemodialysis access were on continuous-flow ventricular assist devices. Brachiocephalic arteriovenous fistulas were performed in all arteriovenous fistula patients, and the average preoperative vein diameter was 4.1 ± 0.9 mm. On 30-day follow-up, the average flow rate was 1262 ± 643 mL/min (880-2220). In arteriovenous fistula patients, one died at 30 days, one arteriovenous fistula required ligation for steal syndrome at 5 months, and one was abandoned after 10.7 months for low flow. Of remaining fistulas, one was converted to an arteriovenous graft at 1.7 years for malfunction (with 5.3 month patency), and one remains open at 4.0 years.

CONCLUSION

Arteriovenous fistulas should be considered in selected patients with ventricular assist devices as a means of long-term hemodialysis access to avoid use of catheters. Maturation and usage of primary arteriovenous fistulas is possible despite lack of pulsatile flow.

Relationship Between SCUBE1 Levels and Echocardiography and Electrocardiography Findings and Epicardial Adipose Tissue/Carotid Intima-Media Thickness in Patients Receiving Renal Replacement Therapy

OBJECTIVES

In patients with advanced-stage chronic kidney disease, renal insufficiency, arterial stiffness, and vascular calcification are strong predictors of cardiovascular risk. Signal peptide-CUB-EGF-like protein-1 (SCUBE1) levels increase during platelet activation and acute ischemic events. Here, we evaluated associations between SCUBE1 levels and electrocardiographic/echocardiographic findings, epicardial adipose tissue thickness, and carotid intimamedia thickness in patients with chronic kidney disease.

MATERIALS AND METHODS

Our study included 21 renal transplant recipients, 20 peritoneal dialysis patients, 20 hemodialysis patients, 20 predialysis patients with glomerular filtration rate < 30 mL/min, and 16 healthy volunteers.

RESULTS

We found no differences in SCUBE1 levels between patient groups and healthy volunteers, regardless of history of diabetes mellitus, myocardial infarction, cerebrovascular events, and hypertension. SCUBE1 levels correlated with C-reactive protein in renal transplant recipients; magnesium in peritoneal dialysis patients; erythrocyte sedimentation rate in predialysis patients; and parathyroid hormone, platelet count, calcium-phosphate product, and calcium in hemo dialysis patients. No associations were shown between SCUBE1 levels and electrocardiographic/echocardiographic findings. Elevated C-reactive protein in predialysis patients was associated with cardiac valvular pathologies. In hemodialysis patients, SCUBE1 levels increased after hemodialysis (P = .007). Levels were higher in healthy individuals with normal echocardiography and predialysis patients with left ventricular diastolic dysfunction. Positive correlations were found between carotid intima-media thickness and SCUBE1 levels in dialysis patients (P < .05), but no study groups showed correlations regarding epicardial adipose tissue thickness.

CONCLUSIONS

Hemodialysis may contribute to cardiovascular events because of increased SCUBE1 levels after hemodialysis; however, no association was shown between SCUBE1 and electrocardiography/echocardiography findings. We found no correlations between epicardial adipose tissue thickness and SCUBE1 levels, and levels were significantly higher in healthy patients and in predialysis patients without left ventricular diastolic dysfunction. However, correlations were shown between SCUBE1 levels and carotid intima-media thickness and secondary hyperparathyroidism markers, indicating associations with atherosclerosis and bone mineral disease in dialysis patients.

Acute kidney injury following left ventricular assist device implantation: Contemporary insights and future perspectives

Currently, an increasing number of patients with end-stage heart failure are being treated with left ventricular assist device (LVAD) therapy as bridge-to-transplantation, bridge-to-candidacy, or destination therapy (DT). Potential life-threatening complications may occur, specifically in the early post-operative phase, which positions LVAD implantation as a high-risk surgical procedure. Acute kidney injury (AKI) is a frequently observed complication after LVAD implantation and is associated with high morbidity and mortality. The rapidly growing number of LVAD implantations necessitates better approaches of identifying high-risk patients, optimizing peri-operative management, and preventing severe complications such as AKI. This holds especially true for those patients receiving an LVAD as DT, who are typically older (with higher burden of comorbidities) with impaired renal function and at increased post-operative risk. Herein we outline the definition, diagnosis, frequency, pathophysiology, and risk factors for AKI in patients with an LVAD. We also review possible strategies to prevent and manage AKI in this patient population.

Predictors and Outcomes of Renal Replacement Therapy After Left Ventricular Assist Device Implantation

OBJECTIVE

To examine the frequency and outcomes of patients requiring renal replacement therapy (RRT) early after left ventricular assist device (LVAD) implantation.

PATIENTS AND METHODS

We examined use of in-hospital RRT and outcomes in consecutive adults who underwent continuous-flow LVAD implantation from February 15, 2007, through August 8, 2017. Logistic regression was used to examine predictors of RRT. The associations of RRT with outcomes were examined using Cox proportional hazards regression.

RESULTS

Of 354 patients who underwent LVAD implantation, 54 (15%) required in-hospital RRT. Patients receiving RRT had higher preoperative Charlson Comorbidity Index values (median, 5 vs 4; P=.03), Model for End-Stage Liver Disease scores (mean, 19.0 vs 14.5; P<.001), right atrial pressure (mean, 19.1 vs 13.4 mm Hg; P<.001), and estimated 24-hour urine protein levels (median, 357 vs 174 mg; P<.001) and lower preoperative estimated glomerular filtration rate (eGFR) (median, 43 vs 57 mL/min; P<.001) and measured GFR using ¹²⁵I-iothalamate clearance (median, 33 vs 51 mL/min; P=.001) than those who did not require RRT. Approximately 40% of patients with eGFR less than 45 mL/min/1.73 m² and 24-hour urine protein level greater than 400 mg required RRT vs 6% with eGFR greater than45 mL/min/1.73 m² and without significant proteinuria. Lower preoperative eGFR, higher estimated 24-hour urine protein level, higher right atrial pressure, and longer cardiopulmonary bypass time were independent predictors of RRT after LVAD implantation. Of patients requiring in-hospital RRT, 18 (33%) had renal recovery, 18 (33%) required outpatient hemodialysis, and 18 (33%) died before hospital discharge. After median (Q1, Q3) follow-up of 24.3 (8.9, 49.6) months, RRT was associated with increased risk of death (adjusted hazard ratio [HR], 2.86; 95% CI, 1.90-4.33; P<.001) and gastrointestinal bleeding (adjusted HR, 4.47; 95% CI, 2.57-7.75; P<.001).

CONCLUSION

In-hospital RRT is associated with poor prognosis after LVAD. A detailed preoperative assessment of renal function before LVAD may be helpful in risk stratification and patient selection.

Impact of chronic kidney disease on in-hospital outcomes following left ventricular assist device placement: A national perspective

BACKGROUND

Left ventricular assist devices (LVADs) are being increasingly utilized for the treatment of stage-D heart failure. A LVAD is a battery-operated, mechanical pump that assists in pumping blood out of the left ventricle (LV) into the aorta, thereby lowering left ventricular burden. Prevalence of chronic kidney disease (CKD) is increasing in patients receiving LVAD.

OBJECTIVES

The purpose of this study was to compare in-hospital mortality and hospitalization expenditure associated with CKD in patients receiving LVAD implantation.

METHODS

Using the National Inpatient Sample from January 2012 through September 2015, index hospitalizations for LVAD were identified. Based on kidney function, LVAD recipients were divided into three groups: Group 1 included patients with normal renal function or CKD stages I-III. Groups 2 and 3 comprised of patients with CKD stage IV/V, and end-stage renal disease on dialysis respectively.

RESULTS

A total of 20,656 patients received LVAD during the study period. Mean age was 56.1 years; 76.8% were men. In a fully adjusted model, in-hospital mortality was higher in group 2 (OR: 1.33, CI: 1.16-1.50) and highest in group 3 (OR: 8.95, CI: 6.90-11.61). Similarly, the length of hospitalization, and hospitalization cost were higher in group 2 and highest in group 3.

CONCLUSION

Despite improving outcomes in patients receiving LVAD, CKD remained a significant health problem. Worsening in-hospital outcomes paralleling the degree of kidney dysfunction were observed in patients receiving LVADs in this study.

Outcomes after left ventricular assist device implantation in patients with acute kidney injury

OBJECTIVE

The study objective was to compare outcomes for patients with and without acute kidney injury during hospitalizations when left ventricular assist devices are implanted.

METHODS

By using the National Inpatient Sample from 2008 to 2013, we identified patients with an International Classification of Diseases, Ninth Revision procedure code for left ventricular assist device implantation (37.66). We ascertained the presence of acute kidney injury and acute kidney injury requiring dialysis using validated International Classification of Diseases, Ninth Revision codes. We used logistic regression to examine the association of nondialysis-requiring acute kidney injury and acute kidney injury requiring dialysis with mortality, procedural complications, and discharge destination.

RESULTS

We identified 8362 patients who underwent left ventricular assist device implantation, of whom 3760 (45.0%) experienced nondialysis-requiring acute kidney injury and 426 (5.1%) experienced acute kidney injury requiring dialysis. In-hospital mortality was 3.9% for patients without acute kidney injury, 12.2% for patients with nondialysis-requiring acute kidney injury, and 47.4% for patients with acute kidney injury requiring dialysis. Patients with nondialysis-requiring acute kidney injury and acute kidney injury requiring dialysis had higher adjusted odds of mortality (3.24, 95% confidence interval [CI], 2.04-5.13 and 20.8, 95% CI, 9.7-44.2), major bleeding (1.38, 95% CI, 1.08-1.77 and 2.44, 95% CI, 1.47-4.04), sepsis (2.69, 95% CI, 1.93-3.75 and 5.75, 95% CI, 3.46-9.56), and discharge to a nursing facility (2.15, 95% CI, 1.51-3.07 and 5.89, 95% CI, 2.67-12.99).

CONCLUSIONS

More than 1 in 10 patients with acute kidney injury and approximately 1 in 2 patients with acute kidney injury requiring dialysis died during their hospitalization, with only 30% of patients with acute kidney injury requiring dialysis discharged to home. This information is necessary to support shared decision-making for patients with advanced heart failure and acute kidney injury.