Renal risk stratification in left ventricular assist device therapy

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.

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.

Are the current evaluation tools for advanced therapies biased?

PURPOSE OF REVIEW

Despite attention to racial disparities in outcomes for heart failure (HF) and other chronic diseases, progress against these inequities has been gradual at best. The disparities of COVID-19 and police brutality have highlighted the pervasiveness of systemic racism in health outcomes. Whether racial bias impacts patient access to advanced HF therapies is unclear.

RECENT FINDINGS

As documented in other settings, racial bias appears to operate in HF providers' consideration of patients for advanced therapy. Multiple medical and psychosocial elements of the evaluation process are particularly vulnerable to bias.

SUMMARY

Reducing gaps in access to advanced therapies will require commitments at multiple levels to reduce barriers to healthcare access, standardize clinical operations, research the determinants of patient success and increase diversity among providers and researchers. Progress is achievable but likely requires as disruptive and investment of immense resources as in the battle against COVID-19.