Angiotensin-converting enzyme inhibition or mineralocorticoid receptor blockade do not affect prevalence of atrial fibrillation in patients undergoing cardiac surgery

Diuretics for preventing and treating acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is a well-known complication of critical illnesses, significantly affecting morbidity and the risk of death. Diuretics are widely used to ameliorate excess fluid accumulation and oliguria associated with AKI. Their popularity stems from their ability to reduce the energy demands of renal tubular cells by inhibiting transporters and flushing out intratubular casts. Numerous studies have assessed the effects of diuretics in the context of AKI prevention and treatment. However, a comprehensive systematic review addressing this topic has yet to be conducted.

OBJECTIVES

This review aimed to explore the benefits and harms of diuretics for both the prevention and treatment of AKI.

SEARCH METHODS

The Cochrane Kidney and Transplant Register of Studies was searched up to May 2024 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) and quasi-RCTs in which diuretics were used to prevent or treat AKI.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data using standardised data extraction forms. Dichotomous outcomes were expressed as risk ratios (RR) with 95% confidence intervals (CI). Where continuous scales of measurement were used to assess the effects of treatment, the standardised mean difference (SMD) was used. The primary review outcomes for AKI prevention studies were the incidence of AKI and any use of kidney replacement therapy (KRT). For treatment studies, the primary outcome was any use of KRT. The certainty of evidence was assessed per outcome using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 64 studies (83 reports, 9871 participants): 53 prevention studies (8078 participants) and 11 treatment studies (1793 participants). Studies were conducted in the following World Health Organization regions: the Americas (15), Eastern Mediterranean (9), Europe (25), South-East Asia (2), and the Western Pacific (13). Thirty-six studies were single-centre studies, 19 were multicentre, and the setting was unclear in nine studies. Diuretics were compared to placebo, no treatment or conventional therapy, saline solutions (isotonic or hypotonic), 5% dextrose, 5% glucose, Hartmann's solution, and Ringer's acetate. Overall, the risk of bias was low in one study, high in 19 studies, and of some concern in 41 studies. Three studies could not be assessed because they did not report any outcomes of interest. For AKI prevention, compared to control, diuretics may reduce the risk of AKI (38 studies, 5540 participants: RR 0.75, 95%, CI 0.61 to 0.92; I2 = 77%; low-certainty evidence) and probably reduce any use of KRT (32 studies, 4658 participants: RR 0.63, 95% CI 0.43 to 0.91; I2 = 0%, moderate-certainty evidence) and death (33 studies, 6447 participants: RR 0.73, 95% CI 0.59 to 0.92; I2 = 0%; moderate-certainty evidence). The use of diuretics may result in little or no difference in the need for permanent dialysis (2 studies, 956 participants: RR 0.52, 95% CI 0.08 to 3.47; I2 = 21%; low-certainty evidence), hypotension (7 studies, 775 participants: RR 1.27, 95% CI 0.87 to 1.86; I2 = 0%; low-certainty evidence) and hypokalaemia (6 studies, 1383 participants: RR 1.20, 95% CI 0.88 to 1.73; I2 = 43%; low-certainty evidence), and had uncertain effects on arrhythmias (13 studies, 3375 participants: RR 0.77, 95% CI 0.57 to 1.04; I2 = 53%; very-low certainty evidence). Diuretics may make little or no difference to changes in SCr within 30 days (8 studies, 646 participants: SMD 0.41, 95% CI -0.01, to 0.83; I2 = 82%; low-certainty evidence) but it was uncertain whether diuretics increased urinary output (8 studies, 1155 participants: SMD 1.87, 95% CI -0.20 to 3.95; I2 = 99%; very low-certainty evidence). For AKI treatment, diuretics may make little or no difference to any use of KRT (8 studies, 1275 participants: RR 0.93, 95% CI 0.83 to 1.04; I2 = 2%; low-certainty evidence) or death (14 studies, 2052 participants: RR 1.08, 95% CI 0.96 to 1.22; I2 = 0%; low-certainty evidence). Diuretics may increase hypotension (2 studies, 720 participants: RR 1.99, 95% CI 1.16 to 3.41; I2 = 90%; low-certainty evidence) and probably increase arrhythmias (6 studies, 1011 participants: RR 1.62, 95% CI 1.12 to 2.33; I2 = 0%; moderate-certainty evidence). Diuretics may result in little or no difference in hypokalaemia (3 studies, 478 participants: RR 1.52, 95% CI 0.70 to 3.31; I2 = 0%; low-certainty evidence). It was uncertain whether diuretics increased urinary output (3 studies, 329 participants: SMD 4.40, 95% CI -0.94 to 9.74; I2 = 99%; very low-certainty evidence). The need for permanent dialysis and changes in serum creatinine were not reported.

AUTHORS' CONCLUSIONS

When used for the prevention of AKI, diuretics may reduce the risk of AKI. However, our confidence in the effect estimate is limited. Diuretics probably reduce the incidence of KRT use, and we are moderately confident in the effect estimate. When used for the treatment of AKI, diuretics may make little or no difference to any use of KRT, and our confidence in the effect estimate is limited. More RCTs are needed to explore the role of diuretics for treating established AKI.

The Relationship between Using Renin-Angiotensin System Inhibitors with Mortality of Atrial Fibrillation: A Systematic Review and Meta-Analysis

BACKGROUND

Atrial fibrillation (AFib) is a highly prevalent cardiac arrhythmia associated with increased mortality in affected persons. Renin-angiotensin system inhibitors (RASIs) have been suggested as potential therapeutic agents for cardiovascular and renal diseases.

OBJECTIVES

However, the relationship between RASIs and mortality in AFib patients remains uncertain. Therefore, the present study was designed and implemented for this purpose.

METHODS

We searched PubMed/MEDLINE, Embase, Web of Science (WOS), Cochrane Library, and Scopus databases for studies published until 12 February 2024 with relevant keywords. We included studies that reported mortality outcomes in AFib patients treated with RASIs and non-users. The data extraction and quality assessment processes were conducted, and subgroup analyses and sensitivity analyses were done. The data were analyzed by Stata 15 using statistical tests, such as Chi-square and I2 tests.

RESULTS

A total of 15 studies (2007-2024; n=2,178,565 patients) examined the association between RASI drugs and mortality of patients with AFib. The results indicated that compared to the control group, the odds of AFib mortality in the group receiving RASIs were equal to 0.81(95% CI: 0.71-0.92; P-value ≤0.001). The study results did not indicate publication bias (Pvalue= 0.733). During the meta-regression analysis, none of the study variables demonstrated a significant relationship with the observed heterogeneity (P-value > 0.20). Cumulative OR results showed that from 2022 onwards, there was enough evidence to confirm the relationship using RASIs with mortality of patients with AFib.

CONCLUSION

Therefore, this meta-analysis suggests that the use of RASI drugs is associated with reduced AFib mortality. However, the authors emphasize the need for further high-quality studies and large-scale randomized clinical trials to validate these findings.

Association between mineralocorticoid receptor antagonists and kidney harm: A systematic review and meta-analysis of randomized controlled trials

Conflicting data have been reported on the association between mineralocorticoid receptor antagonists (MRAs) and acute kidney injury (AKI). This systematic review and meta-analysis aimed to evaluate whether MRAs affect the risk of AKI. MEDLINE via PubMed, the Cochrane Central Register of Controlled Trials, and the ClinicalTrials.gov website were comprehensively searched to extract all relevant studies. Randomized controlled trials (RCTs) were selected that compared MRA versus placebo or no treatment and had study populations consisting of patients with heart or kidney disease. The primary outcome was AKI. The secondary outcome was kidney injury, including AKI and non-AKI. Thirty-three studies were included in the meta-analysis. MRAs were not associated with an increased risk of AKI (risk ratio [RR] 1.13, 95% confidence interval [CI] 0.88-1.46, p = 0.29, I2 = 15%, 18,065 patients, 13 RCTs, moderate certainty). For the secondary outcome, MRAs were associated with an increased risk of kidney injury (RR 1.52, 95% CI 1.24-1.87, p < 0.01, I2 = 48%, 27,492 patients, 33 RCTs, low certainty). In particular, only canrenone (RR 5.39, 95% CI 2.17-13.37, p < 0.01) and spironolactone (RR 1.78, 95% CI 1.48-2.14, p < 0.01) were associated with an increased risk of kidney injury. However, eplerenone and finerenone seem not to increase the risk of kidney injury in patients with heart or kidney disease. The selection of MRAs might influence the risk of kidney-associated events. Further studies focusing on individual MRAs may be needed to clarify these differences.

The effect of spironolactone in reducing the risk of postoperative atrial fibrillation in patients undergoing coronary artery bypass graft surgery: randomized single-blind placebo-controlled study

BACKGROUND

Postoperative atrial fibrillation (POAF), one of the most common cardiac arrhythmias following coronary artery bypass graft (CABG) surgery is associated with unfavorable outcomes.

OBJECTIVES

This study investigated the effect of spironolactone administered two weeks before surgery on the incidence of POAF in patients undergoing CABG.

METHODS

This randomized single-blind placebo-controlled study was conducted on 130 CABG patients. All patients were randomly divided into intervention and control groups including 65 cases for each group. In the intervention group, patients received 50 mg of spironolactone orally daily for 2 weeks before surgery, and in the control group patients received placebo daily from 2 weeks before surgery. All patients were continuously monitored for the occurrence of POAF for two weeks postoperatively.

RESULTS

The mean age of the patients in the intervention and control groups was 61.7 ± 5.4 and 60 ± 6.7 years, respectively. The incidence of POAF in the intervention and control groups was 7.7% and 20%, respectively (Odds Ratio = 0.33, P = 0.042). All demographic and clinical variables were similar in patients with and without POAF (all P > 0.05).

CONCLUSIONS

Our findings revealed that in comparison to placebo, the use of spironolactone is associated with reduced incidence of POAF in CABG candidates.

Effects of mineralocorticoid receptor antagonists on new-onset or recurrent atrial fibrillation: a Bayesian and frequentist network meta-analysis of randomized trials

Background Clinical and translational research suggests that mineralocorticoid receptor antagonists (MRAs) may prevent atrial fibrosis and electrical remodeling associated with atrial fibrillation (AF). This study aimed to consolidate existing evidence from randomized controlled trials (RCTs) evaluating the effect of MRAs on incident or recurrent AF. Methods Medline, Cochrane Library and Scopus were searched until February 12, 2024. Triple-independent study selection, data extraction and quality assessment were performed. Evidence was pooled using both pairwise and Bayesian and frequentist network meta-analyses. Results Twenty-three RCTs (13,358 participants) were identified. Based on the pairwise random effects meta-analysis, MRAs were associated with a significant reduction in AF events compared to placebo or usual care (risk ratio {RR}= 0.75; 95% confidence interval {CI}= [0.66, 0.87]; P< 0.001; I2= 3%). This protective effect was robust both for new-onset and recurrent AF episodes (subgroup p-value= 0.69), while the baseline HF status was not a significant effect modifier (subgroup p-value= 0.58). MRAs demonstrated a significantly higher reduction in AF events for patients with chronic renal disease compared to placebo (RR= 0.78; 95% CI= [0.62, 0.98]; P= 0.03; I2= 0%). The network meta-analyses revealed that only spironolactone was associated with a significant reduction in AF events (Bayesian RR= 0.76; 95% CI= [0.65, 0.89]; P< 0.001; level of evidence moderate; SUCRA 0.731), while eplerenone and finerenone showed a neutral effect. Conclusion MRAs confer a significant benefit in terms of reducing incident or recurrent AF episodes, irrespective of HF status. In this context, spironolactone may be preferable compared to eplerenone or finerenone.

Incidence and progression of atrial fibrillation in patients with and without heart failure using mineralocorticoid receptor antagonists: a meta-analysis

BACKGROUND

Mineralocorticoid receptor antagonists (MRAs) have emerged as potential therapy to target the underlying arrhythmogenic substrate in atrial fibrillation (AF). Nevertheless, there have been inconsistent results on the impact of MRAs on AF.

OBJECTIVE

We sought to evaluate the effect of MRAs on AF incidence and progression in patients with and without heart failure.

METHODS

Electronic databases were searched up to September, 2022 for randomized controlled trials (RCTs) that evaluated MRA use and reported AF outcomes. Primary outcome was a composite of new-onset or recurrent AF. Safety outcomes included hyperkalemia and gynecomastia risks. A random-effects meta-analysis estimated pooled odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

12 RCTs, comprising 11,419 patients treated with various MRAs were included [5960 (52%) on MRA]. On follow-up (6-39 months), 714 (5.5%) patients developed AF. MRA therapy was associated with a 32% reduction in the risk of new-onset or recurrent AF [OR 0.68 (95% CI 0.51-0.92), I2 = 40%]. On subgroup analysis, the greatest benefit magnitude was demonstrated in reducing AF recurrence [OR 0.50 (95% CI 0.30-0.83)] and among patients with left ventricular dysfunction [OR 0.59 (95% CI 0.40-0.85)]. Gynecomastia, but not hyperkalemia, was associated with MRA use. Meta-regression analysis demonstrated that therapy duration was a significant interaction factor driving the effect size (Pinteraction = 0.013).

CONCLUSION

MRA use is associated with a reduction in AF risk, especially AF progression. A prominent effect is seen in patients with heart failure, further augmented by therapy duration. Prospective trials are warranted to evaluate MRA use as upstream therapy for preventing this common arrhythmia.

Stroke prevention strategies for cardiac surgery: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Stroke is a much-feared complication of cardiac surgery, but existing literature on preventive strategies is fragmented. Hence, a systematic review and meta-analysis of stroke prevention strategies for cardiac surgery was conducted.

METHODS

An electronic literature search was conducted to retrieve randomized controlled trials (RCTs) investigating perioperative interventions for cardiac surgery, with stroke as an outcome. Random-effects meta-analyses were conducted to generate risk ratios (RRs), 95% confidence intervals (95% CI), and forest plots. Descriptive analysis and synthesis of literature was conducted for interventions not amenable to meta-analysis, focusing on risks of stroke, myocardial infarction and study-defined major adverse cardiovascular events (MACE).

RESULTS

Fifty-six RCTs (61 894 patients) were retrieved. Many included trials were underpowered to detect differences in stroke risk. Among pharmacological therapies, only preoperative amiodarone was shown to reduce stroke risk in one trial. Concomitant left atrial appendage closure (LAAC) significantly reduced stroke risk (RR = 0.55, 95% CI = 0.36-0.84, P = 0.006) in patients with preoperative atrial fibrillation, and there was no difference in on-pump versus off-pump coronary artery bypass grafting (CABG) (RR = 0.94, 95% CI = 0.64-1.37, P = 0.735). Much controversy exists in literature on the timing of carotid endarterectomy relative to CABG in patients with severe carotid stenosis. The use of preoperative remote ischemic preconditioning was not found to reduce rates of stroke or MACE.

CONCLUSION

This review presents a comprehensive synthesis of existing interventions for stroke prevention in cardiac surgery, and identifies gaps in research which may benefit from future, large-scale RCTs. LAAC should be considered to reduce stroke incidence in patients with preoperative atrial fibrillation.

Mineralocorticoid receptor antagonists and atrial fibrillation: a meta-analysis of clinical trials

BACKGROUND AND AIMS

Mineralocorticoid receptor antagonists (MRAs) improve cardiovascular outcomes in a variety of settings. This study aimed to assess whether cardioprotective effects of MRAs are modified by heart failure (HF) and atrial fibrillation (AF) status and to study their impact on AF events.

METHODS

MEDLINE, Embase, and Cochrane Central databases were searched to 24 March 2023 for randomized controlled trials evaluating the efficacy of MRAs as compared with placebo or usual care in reducing cardiovascular outcomes and AF events in patients with or at risk for cardiovascular diseases. Random-effects models and interaction analyses were used to test for effect modification.

RESULTS

Meta-analysis of seven trials (20 741 participants, mean age: 65.6 years, 32% women) showed that the efficacy of MRAs, as compared with placebo, in reducing a composite of cardiovascular death or HF hospitalization remains consistent across patients with HF [risk ratio = 0.81; 95% confidence interval (CI): 0.67-0.98] and without HF (risk ratio = 0.84; 95% CI: 0.75-0.93; interaction P = .77). Among patients with HF, MRAs reduced cardiovascular death or HF hospitalization in patients with AF (hazard ratio = 0.95; 95% CI: 0.54-1.66) to a similar extent as in those without AF (hazard ratio = 0.82; 95% CI: 0.63-1.07; interaction P = .65). Pooled data from 20 trials (21 791 participants, mean age: 65.2 years, 31.3% women) showed that MRAs reduce AF events (risk ratio = 0.76; 95% CI: 0.67-0.87) in both patients with and without prior AF.

CONCLUSIONS

Mineralocorticoid receptor antagonists are similarly effective in preventing cardiovascular events in patients with and without HF and most likely retain their efficacy regardless of AF status. Mineralocorticoid receptor antagonists may also be moderately effective in preventing incident or recurrent AF events.

The Role of Immune Cells Driving Electropathology and Atrial Fibrillation

Atrial fibrillation (AF) is the most common progressive cardiac arrhythmia worldwide and entails serious complications including stroke and heart failure. Despite decades of clinical research, the current treatment of AF is suboptimal. This is due to a lack of knowledge on the mechanistic root causes of AF. Prevailing theories indicate a key role for molecular and structural changes in driving electrical conduction abnormalities in the atria and as such triggering AF. Emerging evidence indicates the role of the altered atrial and systemic immune landscape in driving this so-called electropathology. Immune cells and immune markers play a central role in immune remodeling by exhibiting dual facets. While the activation and recruitment of immune cells contribute to maintaining atrial stability, the excessive activation and pronounced expression of immune markers can foster AF. This review delineates shifts in cardiac composition and the distribution of immune cells in the context of cardiac health and disease, especially AF. A comprehensive exploration of the functions of diverse immune cell types in AF and other cardiac diseases is essential to unravel the intricacies of immune remodeling. Usltimately, we delve into clinical evidence showcasing immune modifications in both the atrial and systemic domains among AF patients, aiming to elucidate immune markers for therapy and diagnostics.

A Systematic Review and Meta-Analysis on Effectiveness of Mineralocorticoid Receptor Antagonists in Reducing the Risk of Atrial Fibrillation

Mineralocorticoid receptor antagonists (MRAs) are known to improve clinical outcomes in heart failure, particularly heart failure with reduced ejection fraction. However, the effect of MRAs on the incidence of and recurrence of atrial fibrillation (AF) is not well established. Therefore, databases, such as PubMed, EMBASE, and Cochrane Central, were searched from inception to September 2021 for randomized controlled trials of MRAs with AF as an outcome. Risk ratios (RRs) with 95% confidence interval (CIs) were combined using the random-effects model. A total of 10 randomized controlled trials (n = 11,356) were included. Our pooled analysis demonstrates that MRAs reduce the risk of AF occurrence by 23% compared with the control therapy (RR 0.77, 95% CI 0.65 to 0.91, p = 0.003, I2 = 40%). Subgroup analysis demonstrated that MRAs reduced the risk of both new-onset AF (RR 0.84, 95% CI 0.61 to 1.16, p = 0.28, I2 = 43%) and recurrent AF (RR 0.73, 95% CI 0.59 to 0.90, p = 0.004, I2 = 26%) similarly; p interaction = 0.48. Our meta-analysis concludes that MRAs reduce the risk of development of AF overall, with consistent effects in new-onset and recurrent AF.

Atrial Cardiomyopathy in Valvular Heart Disease: From Molecular Biology to Clinical Perspectives

This review discusses the evolving topic of atrial cardiomyopathy concerning valvular heart disease. The pathogenesis of atrial cardiomyopathy involves multiple factors, such as valvular disease leading to atrial structural and functional remodeling due to pressure and volume overload. Atrial enlargement and dysfunction can trigger atrial tachyarrhythmia. The complex interaction between valvular disease and atrial cardiomyopathy creates a vicious cycle of aggravating atrial enlargement, dysfunction, and valvular disease severity. Furthermore, atrial remodeling and arrhythmia can predispose to atrial thrombus formation and stroke. The underlying pathomechanism of atrial myopathy involves molecular, cellular, and subcellular alterations resulting in chronic inflammation, atrial fibrosis, and electrophysiological changes. Atrial dysfunction has emerged as an essential determinant of outcomes in valvular disease and heart failure. Despite its predictive value, the detection of atrial fibrosis and dysfunction is challenging and is not included in the clinical routine. Transthoracic echocardiography and cardiac magnetic resonance imaging are the main diagnostic tools for atrial cardiomyopathy. Recently published data have revealed that both left atrial volumes and functional parameters are independent predictors of cardiovascular events in valvular disease. The integration of atrial function assessment in clinical practice might help in early cardiovascular risk estimation, promoting early therapeutic intervention in valvular disease.

Perioperative Management of the Patient at High-Risk for Cardiac Surgery-Associated Acute Kidney Injury

Acute kidney injury (AKI) is one of the most common major complications of cardiac surgery, and is associated with increased morbidity and mortality. Cardiac surgery-associated AKI has a complex, multifactorial etiology, including numerous factors such as primary cardiac dysfunction, hemodynamic derangements of cardiac surgery and cardiopulmonary bypass, and the possibility of a large volume of blood transfusion. There are no truly effective pharmacologic therapies for the management of AKI, and, therefore, anesthesiologists, intensivists, and cardiac surgeons must remain vigilant and attempt to minimize the risk of developing renal dysfunction. This narrative review describes the current state of the scientific literature concerning the specific aspects of cardiac surgery-associated AKI, and presents it in a chronological fashion to aid the perioperative clinician in their approach to this high-risk patient group. The evidence was considered for risk prediction models, preoperative optimization, and the intraoperative and postoperative management of cardiac surgery patients to improve renal outcomes.

New Insights Into Diuretic Use to Treat Congestion in the ICU: Beyond Furosemide

Diuretics are commonly used in critically ill patients with acute kidney injury (AKI) and fluid overload in intensive care units (ICU), furosemide being the diuretic of choice in more than 90% of the cases. Current evidence shows that other diuretics with distinct mechanisms of action could be used with good results in patients with selected profiles. From acetazolamide to tolvaptan, we will discuss recent studies and highlight how specific diuretic mechanisms could help to manage different ICU problems, such as loop diuretic resistance, hypernatremia, hyponatremia, or metabolic alkalosis. The current review tries to shed some light on the potential use of non-loop diuretics based on patient profile and give recommendations for loop diuretic treatment performance focused on what the intensivist and critical care nephrologist need to know based on the current evidence.

The mineralocorticoid receptor in chronic kidney disease

Chronic kidney disease (CKD) is a major public health concern, affecting approximately 10% of the population worldwide. CKD of glomerular or tubular origin leads to the activation of stress mechanisms, including the renin angiotensin aldosterone system and mineralocorticoid receptor (MR) activation. Over the last two decades, blockade of the MR has arisen as a potential therapeutic approach against various forms of kidney disease. In this review, we summarize the experimental studies that have shown a protective effect of MR antagonists (MRAs) in non-diabetic and diabetic CKD animal models. Moreover, we review the main clinical trials that have shown the clinical application of MRAs to reduce albuminuria and, importantly, to slow CKD progression. Recent evidence from the FIDELIO trial showed that the MRA finerenone can reduce hard kidney outcomes when added to the standard of care in CKD associated with type 2 diabetes. Finally, we discuss the effects of MRAs relative to those of SGLT2 inhibitors, as well as the potential benefit of combination therapy to maximize organ protection.

Perioperative Clinical Trials in AKI

To characterize current evidence and current foci of perioperative clinical trials, we systematically reviewed Medline and identified perioperative trials involving 100 or more adult patients undergoing surgery and reporting renal end points that were published in high-impact journals since 2004. We categorized the 101 trials identified based on the nature of the intervention and summarized major trial findings from the five categories most applicable to perioperative management of patients. Trials that targeted ischemia suggested that increasing perioperative renal oxygen delivery with inotropes or blood transfusion does not reliably mitigate acute kidney injury (AKI), although goal-directed therapy with hemodynamic monitors appeared beneficial in some trials. Trials that have targeted inflammation or oxidative stress, including studies of nonsteroidal anti-inflammatory drugs, steroids, N-acetylcysteine, and sodium bicarbonate, have not shown renal benefits, and high-dose perioperative statin treatment increased AKI in some patient groups in two large trials. Balanced crystalloid intravenous fluids appear safer than saline, and crystalloids appear safer than colloids. Liberal compared with restrictive fluid administration reduced AKI in a recent large trial in open abdominal surgery. Remote ischemic preconditioning, although effective in several smaller trials, failed to reduce AKI in two larger trials. The translation of promising preclinical therapies to patients undergoing surgery remains poor, and most interventions that reduced perioperative AKI compared novel surgical management techniques or existing processes of care rather than novel pharmacologic interventions.

Angiotensin II and angiotensin 1-7: which is their role in atrial fibrillation?

Atrial fibrillation (AF) is a significant cause of morbidity and mortality as well as a public health burden considering the high costs of AF-related hospitalizations. Pre-clinical and clinical evidence showed a potential role of the renin angiotensin system (RAS) in the etiopathogenesis of AF. Among RAS mediators, angiotensin II (AII) and angiotensin 1-7 (A1-7) have been mostly investigated in AF. Specifically, the stimulation of the pathway mediated by AII or the inhibition of the pathway mediated by A1-7 may participate in inducing and sustaining AF. In this review, we summarize the evidence showing that both RAS pathways may balance the onset of AF through different biological mechanisms involving inflammation, epicardial adipose tissue (EAT) accumulation, and electrical cardiac remodeling. EAT is a predictor for AF as it may induce its onset through direct (infiltration of epicardial adipocytes into the underlying atrial myocardium) and indirect (release of inflammatory adipokines, the stimulation of oxidative stress, macrophage phenotype switching, and AF triggers) mechanisms. Classic RAS blockers such as angiotensin converting enzyme inhibitors (ACE-I) and angiotensin receptor blockers (ARB) may prevent AF by affecting the accumulation of the EAT, representing a useful therapeutic strategy for preventing AF especially in patients with heart failure and known left ventricular dysfunction. Further studies are necessary to prove this benefit in patients with other cardiovascular diseases. Finally, the possibility of using the A1-7 or ACE2 analogues, to enlarge current therapeutic options for AF, may represent an important field of research.

Effects of Preoperative Angiotensin-Converting Enzyme Inhibitor Therapy on Postoperative Renal Function in Cardiac Surgery

A Best Evidence Topic in cardiac surgery was written according to a structured protocol. The question addressed was-"In patients who undergo cardiac surgery, is preoperative angiotensin-converting enzyme inhibitor therapy associated with postoperative renal dysfunction?" Altogether, 339 papers were found using the reported search. Ten (10) were chosen which best answered the clinical question. The papers were evaluated for bias and heterogeneity using validated tools and the collected results analysed qualitatively. Evidence in the current literature is inconclusive that preoperative administration of angiotensin-converting enzyme inhibitor therapy affects postoperative renal dysfunction in patients undergoing cardiac surgery.

Effects of Mineralocorticoid Receptor Antagonists on Atrial Fibrillation Occurrence: A Systematic Review, Meta-Analysis, and Meta-Regression to Identify Modifying Factors

Background

Mineralocorticoid receptor antagonists (MRAs) have emerged as potential atrial fibrillation (AF) preventive therapy, but inconsistent results have been reported. We aimed to examine the effects of MRAs on AF occurrence and explore factors that could influence the magnitude of the effect size.

Methods and Results

PubMed, Embase, and Cochrane Central databases were used to search for randomized clinical trials and observational studies addressing the effect of MRAs on AF occurrence from database inception through April 03, 2018. We performed a systematic review and random effects meta‐analyses to compute odds ratios with 95% CIs. Meta‐regression was then applied to explore the sources of between‐study heterogeneity. We included 24 studies, 11 randomized clinical trials and 13 observational cohorts, representing a total number of 7914 patients (median age: 64.2 years; median left ventricular ejection fraction: 49.7%; median follow‐up: 12.0 months), 2843 (35.9%) of whom received MRA therapy. Meta‐analyses showed a significant overall reduction in AF occurrence in the MRA‐treated patients versus the control groups (15.0% versus 32.2%; odds ratio, 0.55; 95% CI, 0.44–0.70 [P<0.00001]), with the greatest benefit regarding recurrent AF episodes (odds ratio, 0.42; 95% CI, 0.31–0.59 [P<0.00001]) and with significant heterogeneity among the included studies (I²=54%; P=0.0008). Meta‐regression analyses showed that effect size was significantly associated with older studies and higher AF occurrence rate in the control groups.

Conclusions

MRAs seem to be effective in AF prevention, especially regarding recurrent AF episodes.

Associations between preoperative continuation of renin-angiotensin system inhibitor and cardiac surgery-associated acute kidney injury: a propensity score-matching analysis

BACKGROUND

Cardiac surgery-associated acute kidney injury (CSA-AKI) is associated with high risk for complications and mortality. Whether renin-angiotensin system (RAS) inhibitor should be continued or withdrawn in patients with long-term use before cardiac surgery has been lack of consensus.

METHODS

We performed this prospective observational cohort study and recruited cardiac surgery patients in the surgical intensive care units between 2000 and 2011. These patients were divided into users and non-users of RAS inhibitor. Propensity score matching and multivariable models were performed to investigate the association between renal outcome, mortality, and preoperative use of RAS inhibitor.

RESULTS

Preoperative use of RAS inhibitor was identified as the independent protective factor for AKI development (OR 0.41, 95% CI 0.23, 0.63), AKI severity (stage 3 vs. stage 1, OR 0.35, 95% CI 0.18, 0.69), and renal recovery (OR 3.41, 95% CI 1.84, 5.36). Nevertheless, there was no significant protective effect of RAS inhibitor on in-hospital dialysis, in-hospital mortality, and ensuing development of chronic kidney disease (CKD) after AKI. We created a prediction model of CSA-AKI and indicated that preoperative use of RAS inhibitor provided more protective effect in low-risk than high-risk population.

CONCLUSION

Preoperative use of RAS inhibitor was associated with less AKI development and severity, and higher renal recovery. Although more risk reduction of AKI development was shown in low-risk group by our prediction model, continued use of RAS inhibitor before cardiac surgery could provide protective effect in all patients.

Association of Preoperative Renin-Angiotensin System Inhibitors With Prevention of Postoperative Atrial Fibrillation and Adverse Events: A Systematic Review and Meta-analysis

IMPORTANCE

Postoperative atrial fibrillation (POAF) is a well-known complication after cardiac surgery. Renin-angiotensin system inhibitors (RASIs) have been suggested as an upstream therapy for selected patients with AF; however, evidence in the surgical setting is limited.

OBJECTIVE

To evaluate the role of preoperative RASIs in prevention of POAF and adverse events for patients undergoing cardiac surgery.

DATA SOURCES

The PubMed database and the Cochrane Library from inception until December 31, 2018, were searched by using the keywords renin-angiotensin system inhibitors OR angiotensin-converting enzyme inhibitors OR angiotensin receptor blocker OR aldosterone antagonist AND cardiac surgery. ClinicalTrials.gov was searched from inception until December 31, 2018, by using the keywords postoperative atrial fibrillation.

STUDY SELECTION

Randomized clinical trials (RCTs) and observational studies comparing the association between preoperative RASI treatment vs no preoperative RASI treatment (control group) and the incidence of POAF were identified. Eleven unique studies met the selection criteria.

DATA EXTRACTION AND SYNTHESIS

Pooled analysis was performed using a random-effects model. Sensitivity and subgroup analyses of RCTs were performed to test the stability of the overall effect. Metaregression was conducted to explore potential risk of bias.

MAIN OUTCOMES AND MEASURES

The primary outcome was POAF, and the secondary outcomes included rates of stroke and mortality and duration of hospitalization.

RESULTS

Eleven unique studies involving 27 885 unique patients (74.4% male; median age, 65 years [range, 58.5-74.5 years]) were included. Compared with the control group, the RASI group did not have a significantly reduced risk of POAF (odds ratio [OR], 1.04; 95% CI, 0.91-1.19; P = .55; z = 0.60), stroke (OR, 0.86; 95% CI, 0.62-1.19; P = .37; z = 0.90; without significant heterogeneity, P = .11), death (OR, 1.07; 95% CI, 0.85-1.35; P = .56; z = 0.59; without significant heterogeneity, P = .12), composite adverse cardiac events (OR, 1.04; 95% CI, 0.91-1.18; P = .58; z = 0.56), or a reduced hospital stay (weighted mean difference, -0.04; 95% CI, -1.05 to 0.98; P = .94; z = 0.07) using a random-effects model. Pooled analysis focusing on RCTs showed consistent results. The primary overall effect was maintained in sensitivity and subgroup analyses. Metaregression showed that male sex was significantly associated with POAF (τ2 = 0.0065; z = 3.47; Q = 12.047; P < .001) and that use of β-blockers was associated with a significantly reduced risk in developing POAF (τ2 = 0.018; z = -2.24; Q = 5.0091; P = .03).

CONCLUSIONS AND RELEVANCE

The findings from this study suggest that preoperative RASI treatment does not offer additional benefit in reducing the risk of POAF, stroke, death, and hospitalization in the setting of cardiac surgery. The results provide no support for conventional use of RASIs for the possible prevention of POAF and adverse events in patients undergoing cardiac surgery; further randomized data, particularly among those patients with heart failure, are needed.

Mineralocorticoid receptor antagonists and kidney diseases: pathophysiological basis

Chronic kidney disease (CKD) represents a global health concern, and its prevalence is increasing. The ultimate therapeutic option for CKD is kidney transplantation. However, the use of drugs that target specific pathways to delay or halt CKD progression, such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and sodium-glucose co-transporter-2 (SGLT-2) inhibitors is limited in clinical practice. Mineralocorticoid receptor activation in nonclassical tissues, such as the endothelium, smooth muscle cells, inflammatory cells, podocytes, and fibroblasts may have deleterious effects on kidney structure and function. Several preclinical studies have shown that mineralocorticoid receptor antagonists (MRAs) ameliorate or cure kidney injury and dysfunction in different models of kidney disease. In this review, we present the preclinical evidence showing a benefit of MRAs in acute kidney injury, the transition from acute kidney injury to CKD, hypertensive and diabetic nephropathy, glomerulonephritis, and kidney toxicity induced by calcineurin inhibitors. We also discuss the molecular mechanisms responsible for renoprotection related to MRAs that lead to reduced oxidative stress, inflammation, fibrosis, and hemodynamic alterations. The available clinical data support a benefit of MRA in reducing proteinuria in diabetic kidney disease and improving cardiovascular outcomes in CKD patients. Moreover, a benefit of MRAs in kidney transplantation has also been observed. The past and present clinical trials describing the effect of MRAs on kidney injury are presented, and the risk of hyperkalemia and use of other options, such as potassium binding agents or nonsteroidal MRAs, are also addressed. Altogether, the available preclinical and clinical data support a benefit of using MRAs in CKD, an approach that should be further explored in future clinical trials.

The Effect of Spironolactone on the Incidence of Contrast-Induced Nephropathy in Patients Undergoing Cardiac Catheterization: Study Design and Rationale

Introduction

Patients undergoing coronary catheterization are at high risk of developing contrast-induced nephropathy (CIN) acute kidney injury (AKI). Several approaches have been supposed to limit such an effect but with mixed results or non-practical methods. Spironolactone is supposed to be effective as a nephroprotective agent in animal studies. This study will try to measure the effect of spironolactone on the incidence of CIN-AKI in patients undergoing coronary catheterization (angiography angioplasty).

Methods

This study is a single-center, investigator-driven, double-blinded randomized controlled study in Iraq-Basra. More than 400 patients admitted for coronary angio unit in our center will be allocated in a 1:1 ratio to receive either spironolactone 200 mg single dose or placebo in addition to their usual premedication.

Planned Outcomes

Primary end point will be CIN defined as more than 25% or 0.3 mg/dl elevation in serum creatinine (S.Cr.) from baseline during the first 2–3 days after the procedure. We hope to identify or answer an important question regarding CIN in such high-risk patients.

Trial Registration

ClinicalTrials.gov Identifier, NCT03329443.

Effects of anti-hypertensive treatment on major cardiovascular events in populations within prehypertensive levels: a systematic review and meta-analysis

Uncertainties still remain in terms of the efficacy of anti-hypertensive treatment on the risk of major cardiovascular (CV) events within prehypertensive levels. This review aims to assess the efficacy and safety of anti-hypertensives on the CV risks in populations within prehypertensive levels. Randomized controlled trials (RCTs) concerning active treatment vs placebo in populations within prehypertensive levels were identified through electronic database and manual search. Outcomes included the first co-primary outcomes, stroke, heart failure (HF), myocardial infarction (MI), all-cause mortality, and cardiovascular mortality. The first co-primary outcomes were defined as composite cardiovascular disease (CVD) events in the included studies. A total of 29 RCTs involving 127,641 participants were identified. Pooled analysis showed active treatment was associated with a significant 7% reduction in risk of the first co-primary outcomes, 14% in stroke, and 10% in HF as compared to placebo (0.86, 0.77-0.96; 0.93, 0.89-0.98; and 0.90, 0.83-0.97). However, there were no significant reductions in risk of MI, all-cause mortality, and cardiovascular mortality. A significant reduction in risk of the first co-primary outcomes was observed in subpopulations with systolic blood pressure (SBP) 130-139 mmHg (0.94, 0.89-0.99) or prior CVDs (0.88, 0.82-0.94). Meta-regression analyses showed no significant relative risk reductions proportional to the magnitude of the mean baseline BP, mean on-treatment BP, the mean absolute change in BP, the proportion of patients with hypertension, and mean age. In summary, anti-hypertensive treatment has beneficial cardiovascular effects in populations within prehypertensive levels, especially in subpopulations with SBP 130-139 mmHg or prior CVDs.

The Risk of Oxygen during Cardiac Surgery (ROCS) trial: study protocol for a randomized clinical trial

Background

Anesthesiologists administer excess supplemental oxygen (hyper-oxygenation) to patients during surgery to avoid hypoxia. Hyper-oxygenation, however, may increase the generation of reactive oxygen species and cause oxidative damage. In cardiac surgery, increased oxidative damage has been associated with postoperative kidney and brain injury. We hypothesize that maintenance of normoxia during cardiac surgery (physiologic oxygenation) decreases kidney injury and oxidative damage compared to hyper-oxygenation.

Methods/design

The Risk of Oxygen during Cardiac Surgery (ROCS) trial will randomly assign 200 cardiac surgery patients to receive physiologic oxygenation, defined as the lowest fraction of inspired oxygen (FIO₂) necessary to maintain an arterial hemoglobin saturation of 95 to 97%, or hyper-oxygenation (FIO₂ = 1.0) during surgery. The primary clinical endpoint is serum creatinine change from baseline to postoperative day 2, and the primary mechanism endpoint is change in plasma concentrations of F₂-isoprostanes and isofurans. Secondary endpoints include superoxide production, clinical delirium, myocardial injury, and length of stay. An endothelial function substudy will examine the effects of oxygen treatment and oxidative stress on endothelial function, measured using flow mediated dilation, peripheral arterial tonometry, and wire tension myography of epicardial fat arterioles.

Discussion

The ROCS trial will test the hypothesis that intraoperative physiologic oxygenation decreases oxidative damage and organ injury compared to hyper-oxygenation in patients undergoing cardiac surgery.

Trial registration

ClinicalTrials.gov, ID: NCT02361944. Registered on the 30th of January 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2021-5) contains supplementary material, which is available to authorized users.

Acute kidney injury following cardiac surgery: current understanding and future directions

Acute kidney injury (AKI) complicates recovery from cardiac surgery in up to 30 % of patients, injures and impairs the function of the brain, lungs, and gut, and places patients at a 5-fold increased risk of death during hospitalization. Renal ischemia, reperfusion, inflammation, hemolysis, oxidative stress, cholesterol emboli, and toxins contribute to the development and progression of AKI. Preventive strategies are limited, but current evidence supports maintenance of renal perfusion and intravascular volume while avoiding venous congestion, administration of balanced salt as opposed to high-chloride intravenous fluids, and the avoidance or limitation of cardiopulmonary bypass exposure. AKI that requires renal replacement therapy occurs in 2–5 % of patients following cardiac surgery and is associated with 50 % mortality. For those who recover from renal replacement therapy or even mild AKI, progression to chronic kidney disease in the ensuing months and years is more likely than for those who do not develop AKI. Cardiac surgery continues to be a popular clinical model to evaluate novel therapeutics, off-label use of existing medications, and nonpharmacologic treatments for AKI, since cardiac surgery is fairly common, typically elective, provides a relatively standardized insult, and patients remain hospitalized and monitored following surgery. More efficient and time-sensitive methods to diagnose AKI are imperative to reduce this negative outcome. The discovery and validation of renal damage biomarkers should in time supplant creatinine-based criteria for the clinical diagnosis of AKI.

Mineralocorticoid receptor antagonists and atrial fibrillation: a meta-analysis

AIMS

Aldosterone has been implicated in atrial remodelling representing a potential target for upstream therapies. Accumulating evidence suggests that mineralocorticoid receptor blockade may have favourable effects on atrial fibrillation (AF) development, although some controversial results have been published. We, therefore, conducted a meta-analysis of randomized clinical trials (RCTs) and observational studies in order to examine the protective role of mineralocorticoid receptor antagonists (MRAs) on AF.

METHODS AND RESULTS

Of the 1337 initially identified records, 3 RCTs and 2 observational studies with 3640 patients were finally analysed. The pooled analysis of the included studies demonstrated that patients treated with MRAs have 31% lower risk of AF compared with controls [relative ratio (RR): 0.69; 95% confidence interval (CI): 0.58-0.83] without any heterogeneity across the studies (I(2) = 0%). This effect was consistent across RCTs (RR: 0.72; 95% CI: 0.55-0.94) and observational studies (RR: 0.67; 95% CI: 0.53-0.84) without heterogeneity. Also, MRAs reduce the risk of AF in both heart failure (HF) (RR: 0.63; 95% CI: 0.50-0.80) and after cardiac surgery (RR: 0.77; 95% CI: 0.61-0.98). Analysing the relative impact of eplerenone and spironolactone, we showed that only eplerenone significantly reduces AF burden (RR: 0.64; 95% CI: 0.44-0.90).

CONCLUSION

Our meta-analysis suggests that MRAs may be effective in AF prevention especially in the HF setting. However, there are insufficient data for the widespread use of aldosterone antagonists solely for AF prevention. Larger RCTs with long-term follow-up in different clinical settings are needed to clarify the impact of MRAs on AF.

Perioperative angiotensin-converting enzyme inhibitors or angiotensin II type 1 receptor blockers for preventing mortality and morbidity in adults

BACKGROUND

Perioperative hypertension requires careful management. Angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II type 1 receptor blockers (ARBs) have shown efficacy in treating hypertension associated with surgery. However, there is lack of consensus about whether they can prevent mortality and morbidity.

OBJECTIVES

To systematically assess the benefits and harms of administration of ACEIs or ARBs perioperatively for the prevention of mortality and morbidity in adults (aged 18 years and above) undergoing any type of surgery under general anaesthesia.

SEARCH METHODS

We searched the current issue of the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 12), Ovid MEDLINE (1966 to 8 December 2014), EMBASE (1980 to 8 December 2014), and references of the retrieved randomized trials, meta-analyses, and systematic reviews.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) comparing perioperative administration of ACEIs or ARBs with placebo in adults (aged 18 years and above) undergoing any type of surgery under general anaesthesia. We excluded studies in which participants underwent procedures that required local anaesthesia only, or participants who had already been on ACEIs or ARBs.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, assessed the risk of bias, and extracted data. We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included seven RCTs with a total of 571 participants in the review. Two of the seven trials involved 36 participants undergoing non-cardiac vascular surgery (infrarenal aortic surgery), and five involved 535 participants undergoing cardiac surgery, including valvular surgery, coronary artery bypass surgery, and cardiopulmonary bypass surgery. The intervention was started from 11 days to 25 minutes before surgery in six trials and during surgery in one trial. We considered all seven RCTs to carry a high risk of bias. The effects of ACEIs or ARBs on perioperative mortality and acute myocardial infarction were uncertain because the quality of the evidence was very low. The risk of death was 2.7% in the ACEIs or ARBs group and 1.6% in the placebo group (risk ratio (RR) 1.61; 95% confidence interval (CI) 0.44 to 5.85). The risk of acute myocardial infarction was 1.7% in the ACEIs or ARBs group and 3.0% in the placebo group (RR 0.55; 95% CI 0.14 to 2.26). ACEIs or ARBs may improve congestive heart failure (cardiac index) perioperatively (mean difference (MD) -0.60; 95% CI -0.70 to -0.50, very low-quality evidence). In terms of rate of complications, there was no difference in perioperative cerebrovascular complications (RR 0.48; 95% CI 0.18 to 1.28, very low-quality evidence) and hypotension (RR 1.95; 95% CI 0.86 to 4.41, very low-quality evidence). Cardiac surgery-related renal failure was not reported. ACEIs or ARBs were associated with shortened length of hospital stay (MD -0.54; 95% CI -0.93 to -0.16, P value = 0.005, very low-quality evidence). These findings should be interpreted cautiously due to likely confounding by the clinical backgrounds of the participants. ACEIs or ARBs may shorten the length of hospital stay, (MD -0.54; 95% CI -0.93 to -0.16, very low-quality evidence) Two studies reported adverse events, and there was no evidence of a difference between the ACEIs or ARBs and control groups.

AUTHORS' CONCLUSIONS

Overall, this review did not find evidence to support that perioperative ACEIs or ARBs can prevent mortality, morbidity, and complications (hypotension, perioperative cerebrovascular complications, and cardiac surgery-related renal failure). We found no evidence showing that the use of these drugs may reduce the rate of acute myocardial infarction. However, ACEIs or ARBs may increase cardiac output perioperatively. Due to the low and very low methodology quality, high risk of bias, and lack of power of the included studies, the true effect may be substantially different from the observed estimates. Perioperative (mainly elective cardiac surgery, according to included studies) initiation of ACEIs or ARBs therapy should be individualized.

Publication Speed, Reporting Metrics, and Citation Impact of Cardiovascular Trials Supported by the National Heart, Lung, and Blood Institute

Background

We previously demonstrated that cardiovascular (CV) trials funded by the National Heart, Lung, and Blood Institute (NHLBI) were more likely to be published in a timely manner and receive high raw citation counts if they focused on clinical endpoints. We did not examine the metrics of trial reports, and our citation measures were limited by failure to account for topic-related citation behaviors.

Methods and Results

Of 244 CV trials completed between 2000 and 2011, we identified 184 whose main results were published by August 20, 2014. One investigator who was blinded to rapidity of publication and citation data read each publication and characterized it according to modified Delphi criteria. There were 46 trials (25%) that had Delphi scores of 8 or 9 (of a possible 9); these trials published faster (median time from trial completion to publication, 12.6 [interquartile range {IQR}, 6.7 to 23.3] vs. 21.8 [IQR, 12.1 to 34.9] months; P<0.01). They also had better normalized citation impact (median citation percentile for topic and date of publication, with 0 best and 100 worst, 1.92 [IQR, 0.64 to 7.83] vs. 8.41 [IQR, 1.80 to 24.75]; P=0.002). By random forest regression, we found that the 3 most important predictors of normalized citation percentile values were total costs, intention-to-treat analyses (as a modified Delphi quality measure), and focus on clinical (not surrogate) endpoints.

Conclusions

NHLBI CV trials were more likely to publish results quickly and yield higher topic-normalized citation impact if they reported results according to well-defined metrics, along with focus on clinical endpoints.

Clinical risk factors of postoperative hyperkalemia after adrenalectomy in patients with aldosterone-producing adenoma

OBJECTIVE

Unilateral adrenalectomy is the first-line treatment for aldosterone-producing adenomas (APA). Hyperkalemia after adrenalectomy because of contralateral zona glomerulosa insufficiency has been reported. We investigated clinical risk factors to predict postoperative hyperkalemia in patients with APA undergoing adrenalectomy.

DESIGN AND METHODS

This study was conducted by retrospectively reviewing medical records from 2000 to 2012 at Seoul National University Hospital and two other tertiary centers. Data from 124 patients who underwent adrenalectomy were included. Hyperkalemia was defined as serum potassium >5.5 mmol/l. Clinical preoperative risk factors included age, blood pressure, plasma renin activity (PRA), plasma aldosterone concentration (PAC), serum potassium, serum creatinine, glomerular filtration rate (GFR), the mass size on pathology, and mineralocorticoid receptor (MR) antagonist use.

RESULTS

Out of 124 patients, 13 (10.5%) developed postoperative hyperkalemia. The incidences of transient and persistent hyperkalemia were 3.2 and 7.3% respectively. Preoperative PRA and PAC were not significantly different in postoperative hyperkalemic patients compared with normokalemic patients. Patients with persistent hyperkalemia were older, had a longer duration of hypertension, larger mass size on pathology, and lower GFR (all P<0.05). The incidence of postoperative hyperkalemia was not different between MR antagonist users and non-users.

CONCLUSION

Older age (≥53 years), longer duration of hypertension (≥9.5 years), larger mass size on pathology (≥1.95 cm), and impaired preoperative renal function (GFR <58.2 ml/min) were associated with prolonged postoperative hyperkalemia in patients with APA. MR antagonist use did not prevent postoperative hyperkalemia.

Preoperative renin-angiotensin system inhibitors use linked to reduced acute kidney injury: a systematic review and meta-analysis

BACKGROUND

Previous trials of interventions to prevent acute kidney injury (AKI) have been unsuccessful and additional interventions are needed. Existing reviews of preoperative renin-angiotensin system (RAS) inhibitors have suggested harm. We included more recent studies and conducted this meta-analysis to evaluate the risk of postoperative AKI in patients who received preoperative RAS inhibitors.

METHODS

A literature search was performed using MEDLINE, EMBASE and Cochrane Database of Systematic Reviews from inception through October, 2014. Studies that reported relative risks, odds ratios or hazard ratios comparing the AKI risk in patients who received preoperative RAS inhibitors versus those who did not were included. We performed the prespecified sensitivity analysis including only propensity score-based studies. Mortality risk was evaluated among the studies that reported AKI outcome. Pooled risk ratios (RR) and 95% confidence interval (CI) were calculated using a random-effect, generic inverse variance method.

RESULTS

Twenty-four studies (1 randomized controlled trial and 23 cohort studies) with 102 675 patients were included in the analysis to assess the risk of postoperative AKI and preoperative RAS inhibitors use. The pooled RR of AKI in patients receiving RAS inhibitors was 1.05 (95% CI: 0.92-1.20). The meta-analysis of the RCT and 11 studies with propensity score analysis demonstrated the pooled RR of AKI in patients receiving RAS inhibitors of 0.92 (95% CI: 0.85-0.99). Within the selected studies, preoperative RAS inhibitor therapy was not associated with a significant increase or decrease in mortality (RR: 0.93; 95% CI: 0.80-1.09).

CONCLUSIONS

Our meta-analysis demonstrates an association between preoperative RAS inhibitor treatment and lower incidence of AKI.

Hypertension is associated with preamyloid oligomers in human atrium: a missing link in atrial pathophysiology?

Background

Increasing evidence indicates that proteotoxicity plays a pathophysiologic role in experimental and human cardiomyopathy. In organ‐specific amyloidoses, soluble protein oligomers are the primary cytotoxic species in the process of protein aggregation. While isolated atrial amyloidosis can develop with aging, the presence of preamyloid oligomers (PAOs) in atrial tissue has not been previously investigated.

Methods and Results

Atrial samples were collected during elective cardiac surgery in patients without a history of atrial arrhythmias, congestive heart failure, cardiomyopathy, or amyloidosis. Immunohistochemistry was performed for PAOs using a conformation‐specific antibody, as well as for candidate proteins identified previously in isolated atrial amyloidosis. Using a myocardium‐specific marker, the fraction of myocardium colocalizing with PAOs (PAO burden) was quantified (green/red ratio). Atrial samples were obtained from 92 patients, with a mean age of 61.7±13.8 years. Most patients (62%) were male, 23% had diabetes, 72% had hypertension, and 42% had coronary artery disease. A majority (n=62) underwent aortic valve replacement, with fewer undergoing coronary artery bypass grafting (n=34) or mitral valve replacement/repair (n=24). Immunostaining detected intracellular PAOs in a majority of atrial samples, with a heterogeneous distribution throughout the myocardium. Mean green/red ratio value for the samples was 0.11±0.1 (range 0.03 to 0.77), with a value ≥0.05 in 74 patients. Atrial natriuretic peptide colocalized with PAOs in myocardium, whereas transthyretin was located in the interstitium. Adjusting for multiple covariates, PAO burden was independently associated with the presence of hypertension.

Conclusion

PAOs are frequently detected in human atrium, where their presence is associated with clinical hypertension.

Meta-analysis of the effects of preoperative renin-angiotensin system inhibitor therapy on major adverse cardiac events in patients undergoing cardiac surgery

The purpose of this meta-analysis was to assess the role of preoperative renin-angiotensin system inhibitor (RASI) therapy on major adverse cardiac events (MACE) in patients undergoing cardiac surgery. The Medline, Cochrane Library and Embase databases were searched for clinical studies published up to May 2014. Studies that evaluated the effects of preoperative RASI therapy in cardiac surgery were included. Odds ratio (OR) estimates were generated under a random-effects model. After a literature search in the major databases, 18 studies were identified [three randomized prospective clinical trials (RCTs) and 15 observational trials] that reported outcomes of 54 528 cardiac surgery patients with (n = 22 661; 42%) or without (n = 31 867; 58%) preoperative RASI therapy. Pool analysis indicated that preoperative RASI therapy was not associated with a significant reduction of early all-cause mortality [OR: 1.01; 95% confidence interval (CI) 0.88-1.15, P = 0.93; I(2) = 25%], myocardial infarction (OR: 1.04; 95% CI 0.91-1.19, P = 0.60; I(2) = 16%), or stroke (OR: 0.93; 95% CI 0.75-1.14, P = 0.46; I(2) = 38%). Meta-regression analysis confirmed that there was a strong negative correlation between the percentage of diabetics and early all-cause mortality (P = 0.03). Furthermore, preoperative RASI therapy significantly reduced mortality in studies containing a high proportion of diabetic patients (OR: 0.84; 95% CI 0.71-0.99, P = 0.04; I(2) = 0%). In conclusion, our meta-analysis indicated that although preoperative RASI therapy was not associated with a lower risk of MACE in cardiac surgery patients, it might provide benefits for diabetic patients.

Quantitative Imaging of Preamyloid Oligomers, a Novel Structural Abnormality, in Human Atrial Samples

Abnormalities in atrial myocardium increase the likelihood of arrhythmias, including atrial fibrillation (AF). The deposition of misfolded protein, or amyloidosis, plays an important role in the pathophysiology of many diseases, including human cardiomyopathies. We have shown that genes implicated in amyloidosis are activated in a cellular model of AF, with the development of preamyloid oligomers (PAOs). PAOs are intermediates in the formation of amyloid fibrils, and they are now recognized to be the cytotoxic species during amyloidosis. To investigate the presence of PAOs in human atrium, we developed a microscopic imaging-based protocol to enable robust and reproducible quantitative analysis of PAO burden in atrial samples harvested at the time of elective cardiac surgery. Using PAO- and myocardial-specific antibodies, we found that PAO distribution was typically heterogeneous within a myocardial sample. Rigorous imaging and analysis protocols were developed to quantify the relative area of myocardium containing PAOs, termed the Green/Red ratio (G/R), for a given sample. Using these methods, reproducible G/R values were obtained when different sections of a sample were independently processed, imaged, and analyzed by different investigators. This robust technique will enable studies to investigate the role of this novel structural abnormality in the pathophysiology of and arrhythmia generation in human atrial tissue.

Etomidate use and postoperative outcomes among cardiac surgery patients

BACKGROUND

Although a single dose of etomidate can cause relative adrenal insufficiency, the impact of etomidate exposure on postoperative outcomes is unknown. The objective of this study was to examine the association between a single induction dose of etomidate and clinically important postoperative outcomes after cardiac surgery.

METHODS

The authors retrospectively examined the association between etomidate exposure during induction of anesthesia and postoperative outcomes in patients undergoing cardiac surgery from January 2007 to December 2009 by using multivariate logistic regression analyses and Cox proportional hazards regression analyses. Postoperative outcomes of interest were severe hypotension, mechanical ventilation hours, hospital length of stay, and in-hospital mortality.

RESULTS

Sixty-two percent of 3,127 patients received etomidate. Etomidate recipients had a higher incidence of preoperative congestive heart failure (23.0 vs. 18.3%; P = 0.002) and a lower incidence of preoperative cardiogenic shock (1.3 vs. 4.0%; P < 0.001). The adjusted odds ratio for severe hypotension and in-hospital mortality associated with receiving etomidate was 0.80 (95% CI, 0.58-1.09) and 0.75 (95% CI, 0.45-1.24), respectively, and the adjusted hazard ratio for time to mechanical ventilation removal and time to hospital discharge was 1.10 (95% CI, 1.00-1.21) and 1.07 (95% CI, 0.97-1.18), respectively. Propensity score analysis did not change the association between etomidate use and postoperative outcomes.

CONCLUSIONS

In this study, there was no evidence to suggest that etomidate exposure was associated with severe hypotension, longer mechanical ventilation hours, longer length of hospital stay, or in-hospital mortality. Etomidate should remain an option for induction of anesthesia in cardiac surgery patients.

Heme Oxygenase-1 and Acute Kidney Injury following Cardiac Surgery

BACKGROUND

Intraoperative hemolysis and inflammation are associated with acute kidney injury (AKI) following cardiac surgery. Plasma-free hemoglobin induces heme oxygenase-1 (HO-1) expression. HO-1 degrades heme but increases in experimental models of AKI. This study tested the hypothesis that plasma HO-1 concentrations are associated with intraoperative hemolysis and are increased in patients that develop AKI following cardiac surgery.

METHODS

We measured plasma HO-1, free hemoglobin, and inflammatory markers in 74 patients undergoing cardiopulmonary bypass (CPB). AKI was defined as an increase in serum creatinine concentration of 50% or 0.3 mg/dl within 72 h of surgery.

RESULTS

Twenty-eight percent of patients developed AKI. HO-1 concentrations increased from 4.2 ± 0.2 ng/ml at baseline to 6.6 ± 0.5 ng/ml on postoperative day (POD) 1 (p < 0.001). POD1 HO-1 concentrations were 3.1 ng/ml higher (95% CI 1.1-5.1) in AKI patients, as was the change in HO-1 from baseline to POD1 (4.4 ± 1.3 ng/ml in AKI patients vs. 1.5 ± 0.3 ng/ml in no-AKI patients, p = 0.006). HO-1 concentrations remained elevated in AKI patients even after controlling for AKI risk factors and preoperative drug therapy. Peak-free hemoglobin concentrations correlated with peak HO-1 concentrations on POD1 in patients that developed AKI (p = 0.02). Duration of CPB and post-CPB IL-6 and IL-10 concentrations were also associated with increased HO-1 on POD1.

CONCLUSION

Plasma HO-1 is increased in patients that develop AKI, and CPB duration, hemolysis, and inflammation are associated with increased HO-1 concentrations following cardiac surgery. Strategies that alter hemolysis and HO-1 expression during cardiac surgery may affect risk for AKI.