Assessing Guideline-Directed Medication Therapy for Heart Failure in End-Stage Renal Disease

BACKGROUND

Treatment of heart failure with reduced ejection fraction (HFrEF) requires guideline-directed medication therapy (GDMT) consisting of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker in combination with an indicated beta-blocker. There is concern that end-stage renal disease (ESRD) patients are not being prescribed GDMT. The study aim was to determine whether outcomes differ for patients with HFrEF and ESRD receiving GDMT compared to those not receiving GDMT.

MATERIALS AND METHODS

Adult patients with ESRD and HFrEF admitted to a tertiary teaching hospital over a 2-year period were included. Patients were categorized into GDMT or non-GDMT groups based on their home medications. The length of stay (LOS), mortality, and 30-day hospital readmissions were compared between groups. The incidence of hyperkalemia, hypotension and bradycardia were also evaluated.

RESULTS

A total of 109 patients were included: 88% African-American, 61% males, median age 63 (28-93) years with 25 in the GDMT group and 84 in the non-GDMT group. The LOS did not differ between the GDMT (5 days; 3-14) compared to the non-GDMT group (7 days; 3-28), P = 0.14. Thirty-day hospital readmission and in-hospital mortality were also similar. Hypotension occurred less frequently in the GDMT group compared to the non-GDMT group, 4% versus 27% (P = 0.01).

CONCLUSIONS

Although there were no differences in the primary outcomes, the shorter LOS in the GDMT group may be clinically significant. The fact that most patients with ESRD and HFrEF were not receiving GDMT is a finding that requires further evaluation.

End-Stage Renal Disease Increases Rates of Adverse Glucose Events When Treating Diabetic Ketoacidosis or Hyperosmolar Hyperglycemic State

IN BRIEF Treatment guidelines for diabetic emergencies are well described in patients with normal to moderately impaired kidney function. However, management of patients with end-stage renal disease (ESRD) is an ongoing challenge. This article describes a retrospective study comparing the rates of adverse glucose events (defined as hypoglycemia or a decrease in glucose >200 mg/dL/h) between patients with ESRD and those with normal kidney function who were admitted with diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS). These results indicate that current treatment approaches to DKA or HHS in patients with ESRD are suboptimal and require further evaluation.

Differential roles of caveolin-1 in ouabain-induced Na+/K+-ATPase cardiac signaling and contractility

Binding of ouabain to cardiac Na+/K+-ATPase initiates cell signaling and causes contractility in cardiomyocytes. It is widely accepted that caveolins, structural proteins of caveolae, have been implicated in signal transduction. It is known that caveolae play a role in Na+/K+-ATPase functions. Regulation of caveolin-1 in ouabain-mediated cardiac signaling and contractility has never been reported. The aim of this study is to compare ouabain-induced cardiac signaling and contractility in wild-type (WT) and caveolin-1 knockout (cav-1 KO) mice. In contrast with WT cardiomyocytes, ouabain-induced signaling e.g., activation of phosphoinositide 3-kinase-α/Akt and extracellular signal-regulated kinases (ERK)1/2, and hypertrophic growth were significantly reduced in cav-1 KO cardiomyocytes. Interactions of the Na+/K+-ATPase α1-subunit with caveolin-3 and the Na+/K+-ATPase α1-subunit with PI3K-α were also decreased in cav-1 KO cardiomyocytes. The results from cav-1 KO mouse embryonic fibroblasts also proved that cav-1 significantly attenuated ouabain-induced ERK1/2 activation without alteration in protein and cholesterol distribution in caveolae/lipid rafts. Intriguingly, the effect of ouabain induced positive inotropy in vivo (via transient infusion of ouabain, 0.48 nmol/g body wt) was not attenuated in cav-1 KO mice. Furthermore, ouabain (1-100 μM) induced dose-dependent contractility in isolated working hearts from WT and cav-1 KO mice. The effects of ouabain on contractility between WT and cav-1 KO mice were not significantly different. These results demonstrated differential roles of cav-1 in the regulation of ouabain signaling and contractility. Signaling by ouabain, in contrast to contractility, may be a redundant property of Na+/K+-ATPase.

Defining a rat blood pressure quantitative trait locus to a <81.8 kb congenic segment: comprehensive sequencing and renal transcriptome analysis

Evidence from multiple linkage and genome-wide association studies suggest that human chromosome 2 (HSA2) contains alleles that influence blood pressure (BP). Homologous to a large segment of HSA2 is rat chromosome 9 (RNO9), to which a BP quantitative trait locus (QTL) was previously mapped. The objective of the current study was to further resolve this BP QTL. Eleven congenic strains with introgressed segments spanning <81.8 kb to <1.33 Mb were developed by introgressing genomic segments of RNO9 from the Dahl salt-resistant (R) rat onto the genome of the Dahl salt-sensitive (S) rat and tested for BP. The congenic strain with the shortest introgressed segment spanning <81.8 kb significantly lowered BP of the hypertensive S rat by 25 mmHg and significantly increased its mean survival by 45 days. In contrast, two other congenic strains had increased BP compared with the S. We focused on the <81.8 kb congenic strain, which represents the shortest genomic segment to which a BP QTL has been mapped to date in any species. Sequencing of this entire region in both S and R rats detected 563 variants. The region did not contain any known or predicted rat protein coding genes. Furthermore, a whole genome renal transcriptome analysis between S and the <81.8 kb S.R congenic strain revealed alterations in several critical genes implicated in renal homeostasis. Taken together, our results provide the basis for future studies to examine the relationship between the candidate variants within the QTL region and the renal differentially expressed genes as potential causal mechanisms for BP regulation.

Congenic interval mapping of RNO10 reveals a complex cluster of closely-linked genetic determinants of blood pressure

Genetic dissection of the rat genome for identifying alleles that cause abnormalities in blood pressure (BP) resulted in the mapping of a significant number of BP quantitative trait loci (QTLs). In this study we mapped at least one such BP QTL on rat chromosome 10 (RNO10) as being within the introgressed segment of a S.LEW congenic strain S.LEWx12x2x3x8 spanning 1.34 Mb from 70,725,437 bp to 72,063,232 bp. BP of 3 congenic strains that span shorter segments of this region was additionally examined. Results obtained indicate that LEW alleles that comprise a 375-kb introgressed segment of the congenic strain S.LEWx12x2x3x5 (70,725,437 bp to 71,100,513 bp) increase BP. The magnitude of change in BP exhibited by the 2 strains, S.LEWx12x2x3x8 and S.LEWx12x2x3x5, is the net phenotypic effect of the underlying genetic determinants of BP. In this respect, the current data are superior to previous QTL localization of BP QTL1, which was hypothesized based on differential congenic segments. Genetic dissection using these 2 congenic strains as tools is expected to facilitate further dissection of the regions. Meanwhile, differential congenic segments were used to predict and thereby prioritize regions for candidate gene analysis. Using this approach, 2 distinct regions of 401 kb and 409 kb within S.LEWx12x2x3x8 and a 104 kb region within S.LEWx12x2x3x5 were prioritized for further consideration. Because all of these genetic elements are located within a 1.06-Mb region of RNO10, our study has revealed a remarkable insight into a genomic module comprising very closely-linked, opposing genetic determinants of BP.