Acute Kidney Injury and Renin-Angiotensin System Inhibition Following Transcatheter Aortic Valve Replacement

OBJECTIVE

To identify renin-angiotensin system (RAS) inhibition utilization and discontinuation after transcatheter aortic valve replacement (TAVR) and identify predictors of use and discontinuation.

BACKGROUND

RAS inhibition after TAVR has been associated with lower cardiac mortality and heart failure readmissions.

METHODS

We analyzed 735 consecutive TAVR patients (2014-2019) who survived to hospital discharge at a high-volume TAVR center to determine the utilization and discontinuation of RAS inhibition after TAVR and identify predictors of use and discontinuation. Clinical characteristics, procedural variables, and hospital outcomes were compared between patients receiving vs not receiving discharge RAS inhibitors. Data were compared using t-test and Chi-square test. Multivariable analysis was used to determine independent clinical predictors.

RESULTS

Of the 735 patients, 41.9% were discharged with at least 1 RAS inhibitor. In TAVR patients with heart failure with reduced ejection fraction (HFrEF), defined as EF ≤40%, the utilization of RAS inhibitors at discharge was 51.1%. Patients receiving discharge RAS inhibitors had lower incidences of acute kidney injury (AKI) post procedure (8.1% vs 17.8%; P<.01). Discontinuation of RAS inhibition was observed in approximately 1 in 3 patients and was associated with AKI and pacemaker requirement. Three predictors of RAS inhibitor utilization were higher systolic blood pressure, RAS inhibitor use prior to TAVR, and HFrEF. Conversely, new pacemaker and AKI were associated with less utilization of RAS inhibitors; patients developing AKI were 74% less likely to receive RAS inhibitors than those without AKI.

CONCLUSION

Decreased RAS inhibition provides a potential mechanism for worse outcomes in TAVR patients who develop AKI.

Renin-angiotensin system inhibition reverses the altered triacylglycerol metabolic network in diabetic kidney disease

OBJECTIVE

Dyslipidemia is a significant risk factor for progression of diabetic kidney disease (DKD). Determining the changes in individual lipids and lipid networks across a spectrum of DKD severity may identify lipids that are pathogenic to DKD progression.

METHODS

We performed untargeted lipidomic analysis of kidney cortex tissue from diabetic db/db and db/db eNOS^-/- mice along with non-diabetic littermate controls. A subset of mice were treated with the renin-angiotensin system (RAS) inhibitors, lisinopril and losartan, which improves the DKD phenotype in the db/db eNOS^-/- mouse model.

RESULTS

Of the three independent variables in this study, diabetes had the largest impact on overall lipid levels in the kidney cortex, while eNOS expression and RAS inhibition had smaller impacts on kidney lipid levels. Kidney lipid network architecture, particularly of networks involving glycerolipids such as triacylglycerols, was substantially disrupted by worsening kidney disease in the db/db eNOS^-/- mice compared to the db/db mice, a feature that was reversed with RAS inhibition. This was associated with decreased expression of the stearoyl-CoA desaturases, Scd1 and Scd2, with RAS inhibition.

CONCLUSIONS

In addition to the known salutary effect of RAS inhibition on DKD progression, our results suggest a previously unrecognized role for RAS inhibition on the kidney triacylglycerol lipid metabolic network.

A tale of two diseases: Sarcoidosis, COVID-19 and new therapeutic options with dual RAS inhibition and tetanus-diphtheria vaccine

Sars Cov-2, the pathogen which belongs to the beta coronavirus family that is responsible for COVID-19, uses Angiotensin Converting Enzyme 2 (ACE2) as a receptor, which is responsible for controlling the actions of renin-angiotensin system (RAS). Sars Cov-2 - ACE2 binding leads to a RAS mediated immune response, which targets especially lungs to form ARDS, which in turn, is the most important cause of mortality in COVID-19. CD8+ T cell response dominates over CD4+ T cell response and natural killer cell dysfunction also leads to CD4+ cell dysfunction in COVID-19; this immune dysregulation leads to inappropriate (ARDS) and inadequate (low or quickly waning antibodies) responses to the disease and unfortunately, prepares the patients for re-infections. The peripheral anergy seen in chronic sarcoidosis has much resemblance to COVID-19; CD8+ T cell accumulation is also responsible for inadequate reaction to tuberculin and antigenic stimulus. This article, based on the similarity of COVID-19 and sarcoidosis, discusses a combination of the therapeutic strategy of the tetanus-diphtheria vaccine and dual RAS inhibition, alongside with hydroxychloroquine and antiviral agents, as a solution to overcome the problems described above.

Deciphering the Identity of Renin Cells in Health and Disease

Hypotension and changes in fluid-electrolyte balance pose immediate threats to survival. Juxtaglomerular cells respond to such threats by increasing the synthesis and secretion of renin. In addition, smooth muscle cells (SMCs) along the renal arterioles transform into renin cells until homeostasis has been regained. However, chronic unrelenting stimulation of renin cells leads to severe kidney damage. Here, we discuss the origin, distribution, function, and plasticity of renin cells within the kidney and immune compartments and the consequences of distorting the renin program. Understanding how chronic stimulation of these cells in the context of hypertension may lead to vascular pathology will serve as a foundation for targeted molecular therapies.

ACE2, COVID-19 Infection, Inflammation, and Coagulopathy: Missing Pieces in the Puzzle

Engulfed by the grave consequences of the coronavirus disease 2019 (COVID-19) pandemic, a better understanding of the unique pattern of viral invasion and virulence is of utmost importance. Angiotensin (Ang)-converting enzyme (ACE) 2 is a key component in COVID-19 infection. Expressed on cell membranes in target pulmonary and intestinal host cells, ACE2 serves as an anchor for initial viral homing, binding to COVID-19 spike-protein domains to enable viral entry into cells and subsequent replication. Viral attachment is facilitated by a multiplicity of membranal and circulating proteases that further uncover attachment loci. Inherent or acquired enhancement of membrane ACE2 expression, likely leads to a higher degree of infection and may explain the predisposition to severe disease among males, diabetics, or patients with respiratory or cardiac diseases. Additionally, once attached, viral intracellular translocation and replication leads to depletion of membranal ACE2 through degradation and shedding. ACE2 generates Ang 1-7, which serves a critical role in counterbalancing the vasoconstrictive, pro-inflammatory, and pro-coagulant effects of ACE-induced Ang II. Therefore, Ang 1-7 may decline in tissues infected by COVID-19, leading to unopposed deleterious outcomes of Ang II. This likely leads to microcirculatory derangement with endothelial damage, profound inflammation, and coagulopathy that characterize the more severe clinical manifestations of COVID-19 infection. Our understanding of COVID-ACE2 associations is incomplete, and some conceptual formulations are currently speculative, leading to controversies over issues such as the usage of ACE inhibitors or Ang-receptor blockers (ARBs). This highlights the importance of focusing on ACE2 physiology in the evaluation and management of COVID-19 disease.

Effects of LCZ696 (Sacubitril/Valsartan) on Blood Pressure in Patients with Hypertension: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

LCZ696 (sacubitril/valsartan), a first-in-class angiotensin receptor-neprilysin inhibitor, can significantly reduce blood pressure in patients with heart failure. We performed this meta-analysis to determine the antihypertensive effect of LCZ696 in patients with hypertension.

METHODS

Randomized controlled trials were searched in MEDLINE, the Cochrane Library, and Clinicaltrials.gov. Twelve studies with a total of 6,064 participants were included.

RESULTS

Compared with angiotensin receptor blockers (ARBs), LCZ696 100 mg caused a significant reduction in systolic blood pressure (SBP) (mean difference [MD] -1.58 mm Hg, 95% confidence interval [CI] -2.09 to -1.07, p < 0.05) and diastolic blood pressure (DBP) (MD -0.66 mm Hg, 95% CI -0.98 to -0.33, p < 0.05). LCZ696 200 mg caused a significant reduction in SBP (MD -4.94 mm Hg, 95% CI -6.54 to -3.35, p < 0.05), DBP (MD -2.24 mm Hg, 95% CI -2.74 to -1.75, p < 0.05), 24-h ambulatory SBP (24 h ASBP; MD -3.69 mm Hg, 95% CI -4.80 to -2.58, p < 0.05), and 24-h ADBP (MD -1.71 mm Hg, 95% CI -2.13 to -1.28, p < 0.05). LCZ696 400 mg caused a significant reduction in SBP (MD -6.25 mm Hg, 95% CI -7.90 to -4.61, p < 0.05), DBP (MD -2.30 mm Hg, 95% CI -2.80 to -1.80, p < 0.05), 24-h ASBP (MD -4.31 mm Hg, 95% CI -6.56 to -2.07, p < 0.05), and 24 h ADBP (MD -1.69 mm Hg, 95% CI -2.59 to -0.79, p < 0.05). Compared with LCZ696 200 mg, LCZ696 400 mg caused a significant reduction in SBP (MD 1.71 mm Hg, 95% CI 1.15 to 2.27, p < 0.05), DBP (MD 0.90 mm Hg, 95% CI 0.65 to 1.16, p < 0.05), 24-h ASBP (MD 1.50 mm Hg, 95% CI 0.84 to 2.17, p < 0.05), and 24-h ADBP (MD 0.76 mm Hg, 95% CI 0.47 to 1.06, p < 0.05).

CONCLUSIONS

The blood pressure-lowering effect of LCZ696 is dose-related. This meta-analysis confirms the antihypertensive effects of LCZ696.

Is Hypertension a Real Risk Factor for Poor Prognosis in the COVID-19 Pandemic?

Purpose of Review

There is increasing evidence indicating an association between several risk factors and worse prognosis in patients with coronavirus disease 2019 (COVID-19), including older age, hypertension, heart failure, diabetes, and pulmonary disease. Hypertension is of particular interest because it is common in adults and there are concerns related to the use of renin-angiotensin system (RAS) inhibitors in patients with hypertension infected with COVID-19. Levels of angiotensin-converting enzyme 2 (ACE2), a protein that facilitates entry of coronavirus into cells, may increase in patients using RAS inhibitors. Thus, chronic use of RAS inhibition could potentially lead to a more severe and fatal form of COVID-19. In this review, we provide a critical review to the following questions: (1) Does hypertension influence immunity or ACE2 expression favoring viral infections? (2) Are the risks of complications in hypertension mediated by its treatment? (3) Is aging a major factor associated with worse prognosis in patients with COVID-19 and hypertension?

Recent Findings

Despite the potential involvement of immune responses in the pathogenesis of hypertension, there is no evidence supporting that hypothesis that hypertension or RAS inhibitors contributes to unfavorable outcomes in viral infections. Future investigations adopting a strict protocol for confirming hypertension status as well as assessing associated comorbidities that may influence outcomes are necessary. From the therapeutic perspective, recombinant ACE2 may serve as a potential therapy, but relevant studies in humans are lacking. Definitive evidence regarding the use of RAS inhibitors in patients with COVID-19 is needed; 5 randomized trials examining this issue are currently underway.

Summary

There is no current scientific support for claiming that hypertension or its treatment with RAS inhibitors contribute to unfavorable outcomes in COVID-19.

Impact of Angiotensin II Signaling Blockade on Clinical Outcomes in Patients with Inflammatory Bowel Disease

BACKGROUND

Preclinical data demonstrate that activation of the renin-angiotensin system (RAS) contributes to mucosal inflammation, and RAS inhibition by angiotensin-converting-enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) improves colitis in animal models. Less is known regarding the effects of RAS inhibition on clinical outcomes in inflammatory bowel disease (IBD) patients.

AIM

Evaluate the impact of ACEI and ARB on clinical outcomes in IBD.

METHODS

Rates of IBD-related hospitalizations, operations, and corticosteroid use were evaluated retrospectively in two groups. First, 111 IBD patients taking an ACEI or ARB were compared to nonusers matched 1:1 based on sex, age, diagnosis, disease location, and hypertension diagnosis. Second, outcomes in a cohort of 130 IBD patients were compared prior to and during ACEI/ARB exposure.

RESULTS

Compared to matched controls, all IBD patients together with ACEI/ARB exposure had fewer hospitalizations (OR 0.26, p < 0.01), operations (OR 0.08, p = 0.02), and corticosteroid prescriptions (OR 0.5, p = 0.01). Comparing outcomes before and during ACEI/ARB use, there were no differences in hospitalizations, operations, or corticosteroid use for all IBD patients together, but patients with UC had increased hospitalizations (0.08 pre- vs. 0.16 during ACEI/ARB exposure, p = 0.03) and decreased corticosteroid use (0.24 pre-ACEI/ARB vs. 0.12 during ACEI/ARB exposure, p < 0.01) during ACEI/ARB use.

CONCLUSIONS

IBD patients with ACEI/ARB exposure had fewer hospitalizations, operations, and corticosteroid use compared to matched controls. No differences in outcomes were observed in individuals on ACEI/ARB therapy when compared to a period of time prior to medication exposure.