Patients Undergoing LVAD Placement Demonstrate Marked Sarcopenia Leading to Overestimation of Pre-Implant Glomerular Filtration Rate

Distinctive kidney function trajectories following left ventricular assist device implantation

BACKGROUND

The aim of this study was to assess for distinct kidney function trajectories following left ventricular assist device (LVAD) placement. Cohort studies of LVAD recipients demonstrate that kidney function tends to increase early after LVAD placement, followed by decline and limited sustained improvement. Inter-individual differences in kidney function response may be obscured.

METHODS

We identified continuous flow LVAD implantations in US adults (2016-2017) from INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support). Primary outcomes were estimated glomerular filtration rate (eGFR) trajectories pre-implantation to ∼12 months. Latent class mixed models were applied to primary and validation samples. Clinical differences among trajectory groups were investigated.

RESULTS

Among 4,615 LVAD implantations, 5 eGFR trajectory groups were identified. The 2 largest groups (Groups 1 and 2) made up >80% of the cohort, and were similar to group average trajectories previously reported, with early eGFR rise followed by decline and stabilization. Three novel trajectory groups were found: worsening followed by sustained low kidney function (Group 3, 10.1%), sustained improvement (Group 4, 3.3%), and worsening followed by variation (Group 5, 1.7%). These groups differed in baseline characteristics and outcomes. Group 4 was younger and had more cardiogenic shock and pre-implantation dialysis; Group 3 had higher rates of pre-existing chronic kidney disease, along with older age.

CONCLUSIONS

Novel eGFR trajectories were identified in a national cohort, possibly representing distinct cardiorenal processes. Type 1 cardiorenal syndrome may have been predominant in Group 4, and parenchymal kidney disease may have been predominant in Group 3.

Cardiorenal Syndrome

Cardiorenal syndrome (CRS) describes a specific acute and chronic clinical picture in which the heart or the kidney are primarily dysfunctioning and secondarily affect each other. CRS is divided into five classes: acute and chronic CRS, acute and chronic renocardiac syndromes, and secondary dysfunction of heart and kidneys. This article specifically details the classification and the epidemiology, some risk factors, and the pathophysiology of CRS. Some emerging aspects of CRS are also discussed, such as CRS in patients with end-stage heart failure, with mechanical ventricular assistance, and after heart transplantation. Finally, some aspects of pediatric CRS are detailed.

Prediction of acute kidney injury after left ventricular assist device implantation: Evaluation of clinical risk scores

Acute kidney injury (AKI) is frequent in patients scheduled for implantation of a left ventricular assist device (LVAD) and associated with increased mortality. Although several risk models for the prediction of postoperative renal replacement therapy (RRT) have been developed for cardiothoracic patients, none of these scoring systems have been validated in LVAD patients. A retrospective, single center analysis of all patients undergoing LVAD implantation between September 2013 and July 2016 was performed. Primary outcome was AKI requiring RRT within 14 days after surgery. The predictive capacity of the Cleveland Clinic Score (CCS), the Society of Thoracic Surgeons Score (STS), and the Simplified Renal Index Score (SRI) were evaluated. 76 patients underwent LVAD implantation, 19 patients were excluded due to preoperative RRT. RRT was associated with a prolonged ventilation time, length of stay on the ICU and 180 day mortality (14(60.9%) vs 6(17.6%), P < .01). Whereas the Thakar Score (7.43 ± 1.75 vs 6.44 ± 1.44, P = .02) and the Mehta Score (28.12 ± 15.08 vs 21.53 ± 5.43, P = .02) were significantly higher in patients with RRT than in those without RRT, the SRI did not differ between these groups (3.96 ± 1.15 vs 3.44 ± 1.05, P = .08). Using ROC analyses, CCS, STS, and SRI showed moderate predictive capacity for RRT with an AUC of 0.661 ± 0.073 (P = .040), 0.637 ± 0.079 (P = .792), and 0.618 ± 0.075 (P = .764), respectively, with comparable accuracy in the Delong test. Using univariate logistic regression analysis, only the De Ritis Ratio (OR 2.67, P = .034) and MELD (OR 1.11, P = .028) were identified as predictors of postoperative RRT. Risk scores which are predictive in general cardiac surgery cannot predict RRT in patients after LVAD implantation. Therefore, it seems to be necessary to develop a specific risk score for this patient population.

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

PURPOSE OF REVIEW

The purpose of this review is to describe the effects of mechanical circulatory support (MCS) on changes in kidney function and their relationship with mortality, with an additional focus on the evaluation and management of both preimplant and post-MCS renal dysfunction.

RECENT FINDINGS

Renal dysfunction is highly prevalent in patients referred for MCS and is associated with significantly increased mortality and postoperative acute kidney injury. Most patients, including those with renal dysfunction, experience marked early improvement in renal function with MCS, likely secondary to correction of the cardiogenic shock, volume overload, and neurohormonal activation characteristic of advanced heart failure. Currently, there are no diagnostic tests to definitively distinguish reversible forms of renal dysfunction likely to improve with MCS from irreversible renal dysfunction. Furthermore, the characteristic improvements in renal function observed in the early months of MCS are often transient, with subsequent recurrence of renal dysfunction with longer durations of support. Venous congestion, right ventricular dysfunction, and reduced pulsatility are potential mechanisms involved in resurgence of renal dysfunction following MCS.

SUMMARY

With the exponential growth of MCS, research endeavors to both improve understanding of the mechanisms behind observed changes in renal function and elucidate the device-related effects on the kidney are imperative.