Postoperative Acute Kidney Injury Requiring Dialysis and Glomerular Filtration Rate at Follow-up in Patients With Left Ventricular Assist Device.

Perioperative acute kidney injury requiring dialysis (AKI-D) after left ventricular assist device (LVAD) implantation is associated with poor outcomes, including a mortality ranging from 40% to 75%.1Topkara VK, Coromilas EJ, Garan AR, et al. Preoperative proteinuria and reduced glomerular filtration rate predicts renal replacement therapy in patients supported with continuous-flow left ventricular assist devices.Circ Heart Fail. 2016; 9e002897doi:10.1161/CIRCHEARTFAILURE.115.002897Google Scholar, 2Raichlin E. Baibhav B. Lowes B.D. et al.Outcomes in patients with severe preexisting renal dysfunction after continuous-flow left ventricular assist device implantation.ASAIO J. 2016; 62: 261-267https://doi.org/10.1097/MAT.0000000000000330Crossref PubMed Scopus (24) Google Scholar, 3Nadziakiewicz P. Szygula-Jurkiewicz B. Niklewski T. et al.Effects of left ventricular assist device support on end-organ function in patients with heart failure: comparison of pulsatile- and continuous-flow support in a single-center experience.Transplant Proc. 2016; 48: 1775-1780https://doi.org/10.1016/j.transproceed.2016.01.071Crossref PubMed Scopus (6) Google Scholar, 4Hasin T. Topilsky Y. Schirger J.A. et al.Changes in renal function after implantation of continuous-flow left ventricular assist devices.J Am Coll Cardiol. 2012; 59: 26-36https://doi.org/10.1016/j.jacc.2011.09.038Crossref PubMed Scopus (143) Google Scholar, 5Demirozu Z.T. Etheridge W.B. Radovancevic R. Frazier O.H. Results of HeartMate II left ventricular assist device implantation on renal function in patients requiring post-implant renal replacement therapy.J Heart Lung Transplant. 2011; 30: 182-187https://doi.org/10.1016/j.healun.2010.08.019Abstract Full Text Full Text PDF PubMed Scopus (62) Google Scholar, 6Sandner S.E. Zimpfer D. Zrunek P. et al.Renal function after implantation of continuous versus pulsatile flow left ventricular assist devices.J Heart Lung Transplant. 2008; 27: 469-473https://doi.org/10.1016/j.healun.2007.12.012Abstract Full Text Full Text PDF PubMed Scopus (71) Google Scholar, 7Bansal N. Hailpern S.M. Katz R. et al.Outcomes associated with left ventricular assist devices among recipients with and without end-stage renal disease.JAMA Intern Med. 2018; 178: 204-209https://doi.org/10.1001/jamainternmed.2017.4831Crossref PubMed Scopus (55) Google Scholar There is substantial heterogeneity across studies in the reported proportion of patients able to come off dialysis, ranging from 21% to 67%.1Topkara VK, Coromilas EJ, Garan AR, et al. Preoperative proteinuria and reduced glomerular filtration rate predicts renal replacement therapy in patients supported with continuous-flow left ventricular assist devices.Circ Heart Fail. 2016; 9e002897doi:10.1161/CIRCHEARTFAILURE.115.002897Google Scholar,5Demirozu Z.T. Etheridge W.B. Radovancevic R. Frazier O.H. Results of HeartMate II left ventricular assist device implantation on renal function in patients requiring post-implant renal replacement therapy.J Heart Lung Transplant. 2011; 30: 182-187https://doi.org/10.1016/j.healun.2010.08.019Abstract Full Text Full Text PDF PubMed Scopus (62) Google Scholar For patients who require only short-term dialysis, longer-term kidney outcomes are uncertain. Studies to address this knowledge gap are vital, as glomerular filtration rate is a critical factor in clinical decision making regarding eligibility for subsequent advanced life-saving heart failure therapies. Accordingly, we examined survival and changes in estimated glomerular filtration rate (eGFR) after LVAD implantation in LVAD recipients with and without postoperative AKI-D at a tertiary care hospital. We hypothesized that post-LVAD AKI-D can be followed by improvements in eGFR during long-term follow-up. We conducted a longitudinal cohort study of adults who received a durable continuous-flow LVAD from January 2010 to December 2017 at Tufts Medical Center (Boston, MA). Detailed methods are presented in Item S1. The exposure of interest was AKI-D within the first month of LVAD implantation. AKI-D recovery was defined as sufficient recovery of kidney function to discontinue dialysis. The prespecified primary outcome was percent change in eGFR at 6 months, 1 year, and 2 years from preimplantation baseline eGFR. Baseline eGFR was determined for each patient using the median of all eGFR measurements within the 30 days before LVAD implantation.8Selby N.M. Hill R. Fluck R.J. Standardizing the early identification of acute kidney injury: the NHS England national patient safety alert.Nephron. 2015; 131: 113-117https://doi.org/10.1159/000439146Crossref PubMed Scopus (55) Google Scholar Multivariable linear regression was performed adjusting for baseline eGFR, age, sex, bridge to transplant versus destination therapy status, history of diabetes mellitus, and ischemic cardiomyopathy. During the study period, 288 patients received LVADs, of whom 30 developed AKI-D (Fig S1). Among those with AKI-D, 15 experienced AKI-D recovery while 15 patients died before experiencing recovery. Baseline characteristics are summarized in Table 1 and Tables S1 and S2. Patients with AKI-D had lower baseline eGFR (46 mL/min/1.73 m2 in those who recovered vs 53 mL/min/1.73 m2 in those without recovery) as compared with patients without AKI-D (62 mL/min/1.73 m2) (P = 0.005).Table 1Baseline Characteristics of LVAD RecipientsCharacteristicNo AKI-D (N = 258)AKI-D With Recovery (N = 15)AKI-D Without Recovery (N = 15)P ValueFemale54 (21%)4 (27%)3 (13%)0.7Age (years)56 (12)59 (8)62 (14)0.1Race/ethnicity0.5 Asian7 (3%)0 (0%)1 (7%) White211 (82%)12 (80%)9 (60%) Hispanic20 (8%)2 (13%)3 (20%) Black20 (8%)1 (7%)2 (13%)LVAD indication0.5 Bridge to transplant155 (60%)8 (53%)7 (47%) Destination therapy103 (40%)7 (47%)8 (53%)LVAD device type0.9 HeartMate II113 (44%)6 (40%)6 (40%) HeartWare145 (56%)9 (60%)9 (60%)Baseline eGFR (mL/min/1.73 m2)62 [44, 80]46 [39, 54]53 [36,64]0.005Diabetes mellitus109 (42%)5 (33%)8 (53%)0.5Ischemic cardiomyopathy105 (41%)3 (20%)5 (33%)0.3Serum sodium (mEq/L)134 [131,138]130 [126,134]135 [132,137]0.05Hemoglobin (g/dL)11.0 [9.6, 12.5]10.0 [8.8, 11.9]10.2 [9.3, 10.9]0.1Baseline characteristics are those most proximate to LVAD implantation. Data are presented as mean (SD) or median [interquartile range]. Abbreviations: AKI-D, acute kidney injury requiring dialysis; eGFR, estimated glomerular filtration rate; LVAD, left ventricular assist device. Open table in a new tab Baseline characteristics are those most proximate to LVAD implantation. Data are presented as mean (SD) or median [interquartile range]. Abbreviations: AKI-D, acute kidney injury requiring dialysis; eGFR, estimated glomerular filtration rate; LVAD, left ventricular assist device. Four (13%) patients with AKI-D started dialysis before LVAD implantation, and 22 (73%) patients with AKI-D initiated dialysis within the first week of LVAD implantation (Fig 1A). Initial dialysis modality was continuous venovenous hemodialysis (CVVHD) in all but 1 patient, who started with intermittent hemodialysis (HD) but subsequently transitioned to CVVHD. Among those with AKI-D recovery, 9 were transitioned to intermittent HD before experiencing recovery (Table S3). Median total time on any dialysis modality was 12 days (range, 2-256 days) for those with AKI-D recovery and 17 days (range, 2-146 days) for those without recovery.Figure 1Outcomes among those with and without AKI-D. (A) Kaplan-Meier analysis depicting time to initiation of dialysis among those with AKI-D with and without kidney recovery. P value = 0.47 between those with AKI-D with and without recovery. (B) Kaplan-Meier analysis depicting 1-year survival among those without AKI-D, with AKI-D and kidney recovery, and with AKI-D without recovery. (C) Box plots of eGFR among those without AKI-D and those with AKI-D with kidney recovery on day of implantation and at 30 days, 180 days, 1 year, and 2 years. Dots represent individual eGFR measurements. Within each box, horizontal lines denote median values; boxes extend from the 25th to the 75th percentile of each group’s distribution; vertical lines denote range. Abbreviations: AKI-D, acute kidney injury requiring dialysis; eGFR, estimated glomerular filtration rate.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Six-month mortality was 100% for those with AKI-D without recovery (n = 15), compared with 2 (13%) deaths in the AKI-D group who recovered, and 31 (12%) deaths among those without AKI-D (n = 258). Mortality remained similar between patients with AKI-D who recovered and patients without AKI-D at 1 year (Fig 1B). Among the 15 patients without AKI-D recovery, 12 died while receiving CVVHD and 3 transitioned to intermittent HD before death. Time receiving intermittent HD before death ranged from 1 to 4.5 months. Percent change in eGFR (95% CI) at 6 months, 1 year, and 2 years was 18% (−41%, 4%), 22% (−48%, 4%), and 39% (−75%, -3%), respectively, lower among the 15 patients with AKI-D and subsequent recovery as compared with those without AKI-D in adjusted analysis (Table S4, Fig S2). Individual eGFR trajectories among those with AKI-D are depicted in Fig S3. Our study does have a few limitations. The total number of patients with AKI-D is small. This limits the number of covariates adjusted for. It is also worth noting that interpretation of eGFR can be challenging both in AKI and in LVAD recipients owing to factors such as reduced muscle mass and edema. This study uniquely compares kidney outcomes between those without AKI-D and those with recovery from AKI-D; we found that among those with kidney recovery, percent change in eGFR was similar to LVAD recipients without AKI-D. AKI-D is common and, in the absence of kidney recovery, is associated with extremely high mortality among LVAD recipients. These findings may be useful in decision making about advanced heart failure therapies. Like other populations,9Sohaney R. Yin H. Shahinian V. et al.In-hospital and 1-year mortality trends in a national cohort of US veterans with acute kidney injury.Clin J Am Soc Nephrol. 2022; 17: 184-193https://doi.org/10.2215/CJN.01730221Crossref PubMed Scopus (9) Google Scholar LVAD recipients in this study with AKI-D have poor survival, reflecting illness severity leading to AKI-D. Palliative care should be involved early for these patients. Patients and their family members should be educated about the poor prognosis and decreased quality of life that having both an LVAD and kidney failure entails so that they can participate in shared decision making about whether they want to continue dialysis if kidney recovery seems unlikely. Larger longitudinal studies are needed to identify risk factors for AKI-D and subsequent recovery of kidney function. Research idea and study design: BR, LAI, DEW, HT; data acquisition: BR, LAI, DEW; data analysis and interpretation: BR, LAI, DEW; statistical analysis: BR, LAI, DEW, HT; supervision or mentorship: LAI, DEW, ARV, GG, SSH. Each author contributed important intellectual content during manuscript drafting or revision and agrees to be personally accountable for the individual’s own contributions and to ensure that questions pertaining to the accuracy or integrity of any portion of the work, even one in which the author was not directly involved, are appropriately investigated and resolved, including with documentation in the literature if appropriate. BR was funded by the NIH T32DK007777. Funders did not have a role in the study design, data collection, analysis, reporting, or the decision to submit for publication. The authors declare that they have no relevant financial interests. Received November 21, 2022. Evaluated by 2 external peer reviewers, with direct editorial input from a Statistics/Methods Editor, an Associate Editor, and a Deputy Editor who served as Acting Editor-in-Chief. Accepted in revised form April 22, 2023. The involvement of an Acting Editor-in-Chief was to comply with AJKD’s procedures for potential conflicts of interest for editors, described in the Information for Authors & Journal Policies. Download .pdf (.28 MB) Help with pdf files Supplementary File (PDF)Figures S1-S3, Item S1, Tables S1-S4.