Impact of aldosterone antagonists on the substrate for atrial fibrillation: aldosterone promotes oxidative stress and atrial structural/electrical remodeling

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.

Prevalence of primary aldosteronism in acute stroke or transient ischemic attack: a systematic review and meta-analysis

Background and purpose

Primary aldosteronism (PA) is the most common endocrine cause of secondary hypertension with a prevalence of 14% in patients with newly diagnosed hypertension. Patients with PA experience a higher rate of cardiovascular events including stroke when compared to those with blood pressure matched essential hypertension. This systematic review and meta-analysis summarize current evidence on the prevalence of PA in patients with acute stroke or transient ischemic attack (TIA).

Methods

Two reviewers independently reviewed the literature for observational studies on the prevalence of PA in patients with acute stroke or TIA. MEDLINE and Embase were searched for studies up to December 13, 2023.

Results

Three single center studies conducted in Japan, Singapore and China were found to meet the inclusion criteria. The reported prevalence of PA in two cohort studies of adults with stroke or TIA were 3.1% and 4.0% and a third cross-sectional study in adults under 45 years old revealed a prevalence rate of 12.9%. Following a meta-analysis, the pooled prevalence of PA in adults with stroke or TIA is 5.8% [95% CI 1.6%-12.3%].

Conclusions

A considerable proportion of patients with stroke or TIA may have PA as the underlying cause of their hypertension. Given the increased risk of stroke associated with PA, clinicians should consider screening for PA in hypertensive patients with stroke or TIA. Further research is needed to evaluate the effect of timing and interfering medications on test results, which will inform an evidence-based approach to testing for PA following TIA or stroke.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022328644.

Aldosterone Effect on Cardiac Structure and Function

BACKGROUND

Cardiac remodelling could be a key mechanism in aldosteronemediated cardiovascular morbidity and mortality. Experimental and clinical evidence has demonstrated that aldosterone causes cardiac structural remodelling and dysfunction by its profibrotic and pro-hypertrophic effects, which result mainly from the direct effects on myocardial collagen deposition, inflammation, and oxidative stress. Clinical studies have investigated the aldosterone effects on the heart in different clinical conditions, including general population, essential hypertension, primary aldosteronism, heart failure, and atrial fibrillation. Robust findings indicate that aldosterone or the activation of the cardiac mineralocorticoid receptor can cause damage to myocardial tissue by mechanisms independent of the blood pressure, leading to tissue hypertrophy, fibrosis, and dysfunction.

CONCLUSION

Aldosterone-mediated cardiovascular morbidity and mortality mainly result from cardiac structural and functional alterations. In different clinical settings, aldosterone can induce cardiac structural remodelling and dysfunction via several pathological mechanisms, including cardiac fibrosis, inflammation, and oxidative stress. Aldosterone antagonists could effectively decrease or reverse the detrimental aldosterone-mediated changes in the heart.

Corilagin inhibits angiotensin II-induced atrial fibrosis and fibrillation in mice through the PI3K-Akt pathway

Objectives

Corilagin (Cor) is reported as beiing hepatoprotective, anti-inflammatory, antibacterial, and anti-oxidant, while the effect on atrial fibrosis remains unknown. Therefore, we investigated the protective effect of Cor in angiotensin II (Ang II)-induced atrial fibrosis and atrial fibrillation (AF).

Materials and Methods

C57BL/6 mice (male, 8-10 weeks, n = 40) were subcutaneously infused either with saline or Ang II (2.0 mg/kg/day) and Cor (30 mg/kg) intraperitoneally injected 2 hr before Ang II infusion for 4 weeks. Mice were grouped into the control group (n=8), Cor group (n=8), Ang II group (n=8), and Ang II + Cor group (n=8). Morphological, histological, and biochemical examinations were performed. In vivo, transesophageal burst pacing was used to generate AF.

Results

Cor treatment markedly reduced Ang II-induced AF development in mice. Ang II + Cor therapy potentially decreased the atrial fibrotic area. It significantly decreased the increase in smooth muscle alpha-actin (α-SMA), CTGF, Collagen I, and Collagen III expressions brought on by Ang II treatment. Moreover, Ang II + Cor treatment remarkably decreased the malondialdehyde (MDA) content, whereas superoxide dismutase (SOD) and catalase (CAT) activities were potentially increased (all, P<0.001). In addition, Ang II + Cor significantly reduced Ang II-induced interleukin 1 beta (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNF-α) concentrations in atrial tissues. Furthermore, Cor significantly inhibited Ang II-induced p-PI3K, p-Akt, and NF-κB p-p65 protein expression in atrial tissues.

Conclusion

Our data speculated that Cor could have a protective effect against Ang II-induced atrial fibrosis and AF via down-regulation of the PI3K-Akt pathway.

Detection and modification of biomarkers of inflammation determining successful rhythm control in patients with atrial fibrillation

INTRODUCTION

Multiple pathophysiological mechanisms are involved in the pathogenesis of atrial fibrillation (AF). Growing evidence suggests that both local and systemic inflammation plays a key role even in early stages and its progression towards persisting and permanent AF. Rhythm control therapy via pulmonary vein isolation or cardioversion is the cornerstone of AF therapy for most symptomatic patients, yet arrhythmia recurrence after treatment is still common, especially in patients with persistent AF.

MATERIAL AND METHODS

In this review, we summarize the current state of knowledge of biomarkers of inflammation with prognostic value in patients with atrial fibrillation as well as anti-inflammatory medication with potential benefits after rhythm control therapy.

RESULTS AND DISCUSSION

Both onset of AF, progression and arrhythmia recurrence after rhythm control therapy can be caused by local and systemic inflammation. Various inflammatory biomarkers have been established to predict treatment success. Furthermore, additional anti-inflammatory therapy may significantly improve success rates.

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.

Matrix Metalloproteinases in Cardioembolic Stroke: From Background to Complications

Matrix metalloproteinases (MMPs) are endopeptidases participating in physiological processes of the brain, maintaining the blood-brain barrier integrity and playing a critical role in cerebral ischemia. In the acute phase of stroke activity, the expression of MMPs increase and is associated with adverse effects, but in the post-stroke phase, MMPs contribute to the process of healing by remodeling tissue lesions. The imbalance between MMPs and their inhibitors results in excessive fibrosis associated with the enhanced risk of atrial fibrillation (AF), which is the main cause of cardioembolic strokes. MMPs activity disturbances were observed in the development of hypertension, diabetes, heart failure and vascular disease enclosed in CHA₂DS₂VASc score, the scale commonly used to evaluate the risk of thromboembolic complications risk in AF patients. MMPs involved in hemorrhagic complications of stroke and activated by reperfusion therapy may also worsen the stroke outcome. In the present review, we briefly summarize the role of MMPs in the ischemic stroke with particular consideration of the cardioembolic stroke and its complications. Moreover, we discuss the genetic background, regulation pathways, clinical risk factors and impact of MMPs on the clinical outcome.

Activation of cannabinoid receptor 2 attenuates Angiotensin II-induced atrial fibrillation via a potential NOX/CaMKII mechanism

Background

Atrial fibrillation (AF) is the most frequent arrythmia managed in clinical practice. Several mechanisms have been proposed to contribute to the occurrence and persistence of AF, in which oxidative stress plays a non-negligible role. The endocannabinoid system (ECS) is involved in a variety physiological and pathological processes. Cannabinoid receptor 1 (CB1R) and cannabinoid receptor 2 (CB2R) are expressed in the heart, and studies have shown that activating CB2R has a protective effect on the myocardium. However, the role of CB2R in AF is unknown.

Materials and methods

Angiotensin II (Ang II)-infused mice were treated with the CB2R agonist AM1241 intraperitoneally for 21 days. Atrial structural remodeling, AF inducibility, electrical transmission, oxidative stress and fibrosis were measured in mice.

Results

The susceptibility to AF and the level of oxidative stress were increased significantly in Ang II-infused mice. In addition, nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2), NOX4, and oxidized Ca²⁺/calmodulin-dependent protein kinase II (ox-CaMKII) were highly expressed. More importantly, treatment with AM1241 activated CB2R, resulting in a protective effect.

Conclusion

The present study demonstrates that pharmacological activation of CB2R exerts a protective effect against AF via a potential NOX/CaMKII mechanism. CB2R is a potential therapeutic target for AF.

PAGln, an Atrial Fibrillation-Linked Gut Microbial Metabolite, Acts as a Promoter of Atrial Myocyte Injury

Phenylacetylglutamine (PAGln), a gut microbiota (GM)-derived metabolite, is associated with cardiovascular disease. Studies have shown that disordered GM participated in the progression of atrial fibrillation (AF), but the relationship between PAGln and AF is unclear. This study investigated the characteristics of PAGln in AF patients and its impact on atrial myocytes. Based on our previous metagenomic data, the relative abundance of porA, a critical bacterial enzyme for PAGln synthesis, exhibited an increased tendency in AF. In an independent cohort consisting of 42 controls without AF and 92 AF patients, plasma PAGln levels were higher in AF patients than in controls (p < 0.001) by immunoassay. Notably, PAGln exerted a predictive potential of AF with an AUC of 0.774 (p < 0.001), and a predictive model constructed based on the PAGln and Taiwan AF score further improved the predictive potential. Furthermore, a positive correlation was determined between PAGln and LA diameter. Subsequently, the effect of PAGln intervention was examined on HL-1 cells in vitro, revealing that PAGln increased apoptosis, reactive oxygen species (ROS) production, CaMKII and RyR2 activation and decreased cell viability. In conclusion, increased PAGln was associated with AF, and PAGln might contribute to the AF pathogenesis by promoting oxidative stress and apoptosis in atrial myocytes.

Atrial Fibrillation and Aortic Ectasia as Complications of Primary Aldosteronism: Focus on Pathophysiological Aspects

Primary aldosteronism (PA) is the most common cause of secondary hypertension. A growing body of evidence has suggested that, beyond its well-known effects on blood pressure and electrolyte balance, aldosterone excess can exert pro-inflammatory, pro-oxidant and pro-fibrotic effects on the kidney, blood vessels and heart, leading to potentially harmful pathophysiological consequences. In clinical studies, PA has been associated with an increased risk of cardiovascular, cerebrovascular, renal and metabolic complication compared to essential hypertension, including atrial fibrillation (AF) and aortic ectasia. An increased prevalence of AF in patients with PA has been demonstrated in several clinical studies. Aldosterone excess seems to be involved in the pathogenesis of AF by inducing cardiac structural and electrical remodeling that in turn predisposes to arrhythmogenicity. The association between PA and aortic ectasia is less established, but several studies have demonstrated an effect of aldosterone on aortic stiffness, vascular smooth muscle cells and media composition that, in turn, might lead to an increased risk of aortic dilation and dissection. In this review, we focus on the current evidence regarding the potential role of aldosterone excess in the pathogenesis of AF and aortic ectasia.

Exploring the Relationship of Perivascular Adipose Tissue Inflammation and the Development of Vascular Pathologies

Initially thought to only provide mechanical support for the underlying blood vessels, perivascular adipose tissue (PVAT) has now emerged as a regulator of vascular function. A healthy PVAT exerts anticontractile and anti-inflammatory actions on the underlying vasculature via the release of adipocytokines such as adiponectin, nitric oxide, and omentin. However, dysfunctional PVAT produces more proinflammatory adipocytokines such as leptin, resistin, interleukin- (IL-) 6, IL-1β, and tumor necrosis factor-alpha, thus inducing an inflammatory response that contributes to the pathogenesis of vascular diseases. In this review, current knowledge on the role of PVAT inflammation in the development of vascular pathologies such as atherosclerosis and hypertension was discussed.

Atrial Fibrillation and Hypertension: "Quo Vadis"

Hypertension is one of the most well-established risk factors for atrial fibrillation. Long-standing untreated hypertension leads to structural remodeling and electrophysiologic alterations causing an atrial myopathy that forms a vulnerable substrate for the development and maintenance of atrial fibrillation. Hypertension-induced hemodynamic, inflammatory, hormonal, and autonomic changes all appear to be important contributing factors. Furthermore, hypertension is also associated with several atrial fibrillation-related comorbidities. As such, hypertension may represent an important target for therapy in atrial fibrillation. Clinicians should be aware of pitfalls of the blood pressure measurement in atrial fibrillation. While the auscultatory method is preferred, the use of automated devices appears to be an acceptable method in the ambulatory setting. There are pathophysiologic bases and emerging clinical evidence suggesting the benefit of renin-angiotensin system inhibition in risk reduction of atrial fibrillation development particularly in patients with left ventricular hypertrophy or left ventricular dysfunction. A better understanding of hypertension's pathophysiologic link to atrial fibrillation may lead to the development of novel therapies for the primary prevention of atrial fibrillation. Finally, future studies are needed to address optimal blood pressure goal to minimize the risk of atrial fibrillation-related complications.

Primary Aldosteronism More Prevalent in Patients With Cardioembolic Stroke and Atrial Fibrillation

BACKGROUND

Primary aldosteronism (PA) is the most common cause of secondary hypertension, and patients are at an increased risk of atrial fibrillation (AF) and stroke. We assessed the prevalence of PA in patients with recent stroke.

METHODS

We recruited 300 patients admitted to an acute stroke unit with diagnosis of cerebrovascular accident (haemorrhagic/ischaemic) or transient ischaemic attack. Three months post-stroke, plasma renin and aldosterone were measured. Patients with an elevated aldosterone-renin ratio proceeded to the confirmatory saline loading test.

RESULTS

Twenty-six of 192 (14%) patients had an elevated aldosterone-renin ratio. Three of 14 patients who proceeded to saline loading were confirmed with PA (post-saline aldosterone >138 pmol/l). Another three patients were classified as confirmed/likely PA based on the markedly elevated aldosterone-renin ratio and clinical characteristics. The overall prevalence of PA amongst stroke patients with hypertension was 4.0% (95% confidence interval (CI): 0.9%-7.1%). Prevalence of PA was higher amongst patients with cardioembolic stroke, 11% (95% CI: 1.3%-33%), resistant hypertension, 11% (95% CI: 0.3%-48%), and hypertension and AF, 30% (95%CI: 6.7%-65%). If only young patients or those with hypokalaemia were screened for PA, half of our patients with PA would not have been diagnosed. Our decision tree identified that stroke patients with AF and diastolic blood pressure ≥83mmHg were most likely to have PA.

CONCLUSION

We found that amongst hypertensive patients with stroke, PA was more prevalent in those with AF, or cardioembolic stroke. Screening for PA should be considered for all patients with stroke.

Decreased estimated glomerular filtration rate predicts long-term recurrence after catheter ablation of atrial fibrillation in mild to moderate renal insufficiency

BACKGROUND

Catheter ablation is an established therapy for atrial fibrillation (AF), but recurrence after ablation remains a great challenge. Additionally, little is known about the effect of renal function on the efficiency of AF ablation. This study aimed to evaluate the predictors of the prognosis of catheter ablation for AF, especially the effect of renal function.

METHODS

A total of 306 drug-refractory symptomatic patients with AF who underwent first-time catheter ablation were enrolled in the present study. Individuals underwent circumferential pulmonary vein isolation for paroxysmal AF and stepwise ablation for persistent AF.

RESULTS

The follow-up time was 27.2 ± 19.5 months, 202 patients (66.01%) were free of atrial tachyarrhythmia (non-recurrence group), and the other 104 patients experienced recurrence (recurrence group). The recurrence group had a larger left atrial diameter (LAD) and left atrial volume (LAV), a higher LAV index (LAVI) (both, p < 0.01), and a lower estimated glomerular filtration rate (eGFR) (53.5 ± 14.4 vs. 65.5 ± 13.3 ml/min/1.732, p < 0.001) and creatinine clearance rate (CCr) (85.2 ± 26.1 vs. 101.5 ± 29.4 ml/min, p < 0.05). Multivariate logistic regression indicated both eGFR (p = 0.002) and LAVI (p < 0.001) as independent associated factors for long-term recurrence after single catheter ablation; multivariate Cox proportional hazard regression with backward feature selection identified both eGFR (HR: 0.93, 95% CI: 0.91-0.95, p < 0.001) and LAVI (HR: 1.32, 95% CI: 1.25-1.40, p < 0.001) as independent prognostic factors for recurrence when adjusting other clinical variables.

CONCLUSIONS

Decreased eGFR and elevated LAVI may facilitate the long-term recurrence of atrial tachyarrhythmia after catheter ablation for AF.

The Impact of Spironolactone on Markers of Myocardial Oxidative Status, Inflammation and Remodeling in Hyperthyroid Rats

BACKGROUND

Hyperthyroidism promotes the development and progression of cardiovascular diseases (CVD). Aldosterone, a key mediator of myocardial inflammation, oxidative stress and fibrosis, may be activated in hyperthyroidism.

OBJECTIVE

To assess the impact of hyperthyroidism on aldosterone levels and myocardial oxidative status, inflammatory and fibrotic markers in hyperthyroid rats, and to test if the use of spironolactone (an aldosterone antagonist) attenuates these changes.

METHODS

Adult Wistar rats were randomly distributed into 4 groups; controls, spironolactone treated rats (Spir, 50mg/kg/day), hyperthyroid rats (Hyper, daily intraperitoneal levothyroxine 0.3mg/kg/day), and spironolactone treated hyperthyroid rats (Hyper+Spir) for 4 weeks. Blood pressure (Bp), and levels of serum and myocardial aldosterone, oxidants/antioxidants, inflammatory and fibrotic markers were measured.

RESULTS

Levothyroxine increased serum thyroid hormones and increased Bp, heart rate and heart to bodyweight ratio. Relative to control, serum aldosterone levels were increased in Hyper and Hyper+ Spir groups. In parallel, cardiac lipid peroxides and serum endothelin-1 were increased whereas cardiac superoxide dismutase, catalase, glutathione, and matrix metalloproteinase -2 were reduced in the Hyper group. Spironolactone decreased serum thyroid hormones and improved cardiac lipid peroxides and metalloproteinase -2 levels. The use of spironolactone decreased serum nitrite levels and increased cardiac SOD and glutathione. Cardiac levels of aldosterone, endothelin-1, transforming growth factor-beta and nitrite were similar among all groups.

CONCLUSION

Hyperthyroid status was associated with an increase in aldosterone and oxidant/ inflammatory biomarkers. The use of spironolactone enhanced antioxidant defenses. Aldosterone antagonists may serve as potential drugs to attenuate the development of cardiac disease in hyperthyroidism.

Contribution of the ACE (rs1799752) and CYP11B2 (rs1799998) Gene Polymorphisms to Atrial Fibrillation in the Tunisian Population

BACKGROUND

This study investigated the association of angiotensin-converting enzyme (ACE I/D) and aldosterone synthase (CYP11B2-344C/T) gene polymorphisms in the renin-angiotensin-aldosterone system (RAAS) with atrial fibrillation (AF) in the Tunisian population.

MATERIALS AND METHODS

The study population included 120 patients with AF and 123 age-matched controls. Genotyping of the I/D polymorphism in the ACE gene and the -344C/T polymorphism in the CYP11B2 gene was performed by polymerase chain reaction (PCR) and PCR-RFLP methods, respectively.

RESULTS

The genotype distribution of the ACE I/D and CYP11B2-344C/T polymorphisms was significantly different between AF patients and control participants (p < 0.01 and p < 0.006 respectively). In addition, ACE I/D increased the risk of AF significantly by 3.41-fold for the DD genotype (OR = 3.41; 95% CI [1.39-8.34]; p < 0.007), and after adjusting for confounding factors (age, diabetes, hypertension, and dyslipidemia), the risk was higher (OR = 5.71; 95% CI [1.48-21.98]; p < 0.01). Likewise, the CYP11B2-344C/T polymorphism increased the incidence of AF for the TT genotype (OR = 3.66; 95% CI [1.62-8.27]; p < 0.002) and the CT genotype (OR = 2.68; 95% CI [1.22-5.86]; p < 0.01). After adjusting for confounding factors (age, diabetes, hypertension and dyslipidemia), the risk remained higher for the TT genotype (OR = 3.58; 95% CI [1.08-11.77]; p < 0.03). Furthermore, the haplotype-based association of the ACE I/D and CYP11B2-344C/T polymorphisms showed that the D-T haplotype increased the risk for AF.

CONCLUSION

Our study suggests a significant association of the ACE (I/D) and CYP11B2-344C/T polymorphisms with AF in the Tunisian population.

Radiofrequency catheter ablation combined with spironolactone in the treatment of atrial fibrillation: A single-center randomized controlled study

At present, the question of whether radiofrequency ablation (RFA) combined with spironolactone can reduce the levels of plasma angiotensin II (AngII) and aldosterone (ALD) in patients with atrial fibrillation (AF) and reduce the recurrence of AF has not been reported.

Association of furosemide or hydrochlorothiazide use with risk of atrial fibrillation post pacemaker implantation among elderly patients

Background

Atrial fibrillation (AF) induced by artificial pacing is directly related to atrial remodeling. Previous basic research has shown that furosemide aggravates pathologic myocardial remodeling while hydrochlorothiazide alleviates it. However, whether furosemide or hydrochlorothiazide plays a role in developing AF after pacemaker implantation remains unknown. The study aims to investigate the association between oral furosemide or hydrochlorothiazide and the risk of developing AF after pacemaker implantation.

Methods

After a review of electronic medical records, elderly patients with pacemaker implantation and without a known baseline history of AF were included and information on their use of daily oral furosemide or hydrochlorothiazide was extracted. New incident AF cases were confirmed via the records of outpatient visits. A Cox proportional-hazards model was used to evaluate the association between daily oral furosemide or hydrochlorothiazide and risk of developing AF after pacemaker implantation, after adjustment for potential confounders.

Results

Among a total of 551 patients aged more than 65 years, 157 AF cases were identified after pacemaker implantation during a maximum follow up of 3.0±1.6 years. Of these, 242 had used furosemide and 97 had used hydrochlorothiazide therapy. Patients taking daily oral furosemide had a relatively higher risk of AF after pacemaker implantation [hazard ratio (HR): 1.507, 95% confidence interval (CI): 1.036–2.192; P=0.032] after being adjusted for related disease and prescribed medications, while oral taking of hydrochlorothiazide was shown to be a non-effective factor (HR: 0.666, 95% CI: 0.413–1.074), which had no statistical significance.

Conclusions

Daily oral furosemide might increase the risk of developing AF after pacemaker implantation in elderly patients, while hydrochlorothiazide has no detrimental effect.

Molecular Basis of Atrial Fibrillation Initiation and Maintenance

Atrial fibrillation (AF) is the most common cardiac arrhythmia, largely associated to morbidity and mortality. Over the past decades, research in appearance and progression of this arrhythmia have turned into significant advances in its management. However, the incidence of AF continues to increase with the aging of the population and many important fundamental and translational underlaying mechanisms remain elusive. Here, we review recent advances in molecular and cellular basis for AF initiation, maintenance and progression. We first provide an overview of the basic molecular and electrophysiological mechanisms that lead and characterize AF. Next, we discuss the upstream regulatory factors conducting the underlying mechanisms which drive electrical and structural AF-associated remodeling, including genetic factors (risk variants associated to AF as transcriptional regulators and genetic changes associated to AF), neurohormonal regulation (i.e., cAMP) and oxidative stress imbalance (cGMP and mitochondrial dysfunction). Finally, we discuss the potential therapeutic implications of those findings, the knowledge gaps and consider future approaches to improve clinical management.

Modulating ALDH2 reveals a differential dependence on ROS for hypertrophy and SR Ca2+ release in aldosterone-treated cardiac myocytes

Growing evidence links high aldosterone levels with atrial fibrillation and other heart diseases. Here, we have investigated the functional consequences of culturing adult rat atrial myocytes with aldosterone, at the level of cell size, homeostasis of Ca2+, reactive oxygen species (ROS), and nitrogen oxide (NO). The protein levels of NO synthase (NOS), aldehyde dehydrogenase 2 (ALDH2), NADPH oxidase (NOX), and Na+-Ca2+ exchanger (NCX) were also studied. Aldosterone did not alter the expression of these proteins, except for the NCX, which was enhanced by nearly 100%. Additionally, the hormone inhibited and stimulated, respectively, the production of NO and ROS (the effect on ROS appeared after 24 h of treatment and reached a maximum by 4-6 days, with an EC50 of 1.2 nM). These changes in reactive species generation were blunted by tetrahydrobiopterin (BH4, a NOS cofactor), suggesting the involvement of an uncoupled NOS. An activator (Alda-1) and an inhibitor (daidzin) of ALDH2 were used, to determine if this enzyme activity is related to aldosterone effects, through possible modulation of ROS. Aldosterone produced a ∼10% increase in cell size and, remarkably, this hypertrophic effect, along with the corresponding changes in ROS and NO, were all mimicked by daidzin and prevented by Alda-1. Something different happened with SR Ca2+ release. Aldosterone increased both the magnitude of Ca2+ transients and the incidence of spontaneous Ca2+ oscillations, but these actions were not reproduced by daidzin. Moreover, rather than being prevented, they were further promoted by Alda-1, which also increased the rate of SR Ca2+ reuptake. These results suggest that NOS and ALDH2 may prevent some adverse consequences of aldosteronism (in the case of ALDH2, at the expense of exacerbating SR Ca2+ release). Our data also suggest a hierarchical model in which aldosterone promotes: SR Ca2+ release, then ROS production, and finally hypertrophy.

Abdominal aortic calcification is more severe in unilateral primary aldosteronism patients and is associated with elevated aldosterone and parathyroid hormone levels

Primary aldosteronism (PA) is associated with a higher prevalence of abdominal aortic calcification (AAC). Unilateral and bilateral PA are the most common subtypes of PA. However, no studies have addressed the difference in the prevalence of AAC between the two subtypes. In addition to aldosterone, parathyroid hormone (PTH), an important regulator of calcium metabolism, was also reported to be elevated in individuals with unilateral PA. Therefore, we hypothesized that the prevalence of AAC may be higher in individuals with unilateral PA, which may be related to the plasma aldosterone concentration (PAC) and PTH levels. We included 156 PA patients who underwent adrenal venous sampling and 156 with essential hypertension (EH) matched by age and sex. Of the former, 76 were diagnosed with unilateral PA, and 80 were diagnosed with bilateral PA. The aortic calcification index (ACI) presented the severity of AAC and was measured by adrenal computed tomography scan. Our results showed that compared with the EH group, the prevalence and severity of AAC were higher in PA patients (32.7 vs. 19.6%; 4.32 ± 3.61% vs. 2.53 ± 2.42%, respectively). In the PA subgroup analysis, unilateral PA was associated with a higher and more severe AAC than bilateral PA (40.7 vs. 25.0%; 5.12 ± 4.07% vs. 3.08 ± 2.34%, respectively). Moreover, PAC and PTH levels were higher in individuals with unilateral PA than in those with bilateral PA (P < 0.05). After risk adjustment, multivariate regression analysis revealed that PAC and PTH were positively-associated with AAC in patients with PA (P < 0.05). In conclusion, unilateral PA patients exhibited a higher prevalence of AAC and more severe AAC due to elevated PAC and PTH levels.

Plasma aldosterone and atrial mitochondrial functions of patients undergoing cardiac surgery

Aim: Mitochondrial dysfunction (MD) has been associated with poor outcomes after coronary artery bypass graft surgery. Methods: 58 consecutive patients from the ALDO-POAF Study (NCT02814903) were prospectively included. Plasma aldosterone was assessed at the time of the preoperative consultation and mitochondrial functional studies were performed using atrial appendage tissue collected during surgery. Results: Patients with the highest preoperative plasma aldosterone level had a lower mitochondrial respiratory chain functioning and a lower calcium retention capacity. Chronic kidney disease, patient's age and preoperative high-aldosterone were independent predictors of MD in multivariate analysis. Conclusion: These exploratory data support the use of preventive strategies targeting aldosterone and/or mineralocorticoid receptor activation, in order to prevent perioperative MD and associated poor outcomes.

Uncovering Synergistic Mechanism of Chinese Herbal Medicine in the Treatment of Atrial Fibrillation with Obstructive Sleep Apnea Hypopnea Syndrome by Network Pharmacology

Paroxysmal atrial fibrillation (AF) combined with obstructive sleep apnea hypopnea syndrome (OSAHS) is very common in clinical practice. Traditional Chinese medicine (TCM) rule of regulating the liver based on psycho-cardiology shows satisfactory effectiveness in the treatment of paroxysmal AF combined with OSAHS. However, its underlying pharmacological mechanism has not yet been elucidated. This study applied network pharmacology to identify 94 active components in the six TCM liver-regulating herbs and 182 corresponding targets from several databases and comprehensive literature studies, as well as retrieved AF combined with OSAHS-related targets. Cytoscape software was adopted to construct the component-component target network and component-putative target-AF combined with OSAHS target network. Then, we obtained 38 putative therapeutic targets against AF combined with OSAHS. After the production of a putative therapeutic target interaction network, topological analysis was adopted to determine the core targets of TCM liver-regulating herbs in the treatment of paroxysmal AF combined with OSAHS. For all putative therapeutic targets, biological process analysis and pathway enrichment analysis were utilized to investigate the possible mechanism of TCM liver-regulating herbs in the treatment of paroxysmal AF combined with OSAHS. Mechanistically, it included positive regulation of nitric oxide biosynthetic process, aging, response to hypoxia, TNF signaling pathway, HIF-1 signaling pathway, PI3K-Akt signaling pathway, neuroactive ligand-receptor interaction, and calcium signaling pathway. Especially, six core targets of TCM liver-regulating herbs, namely, TNF, STAT3, AKT1, IL-6, TP53, and INS, were significant in the regulation of the above biological processes and pathways. This study demonstrates the multicomponent, multitarget, and multipathway feature of TCM liver-regulating herbs, provides an extensional foundation for further research, and facilitates the reasonable application of TCM liver-regulating herbs in treating paroxysmal AF combined with OSAHS.

Spironolactone and perioperative atrial fibrillation occurrence in cardiac surgery patients: Rationale and design of the ALDOCURE trial

BACKGROUND

After artery bypass grafting (CABG), the presence of perioperative AF (POAF) is associated with greater short- and long-term cardiovascular morbidity. Underlying POAF mechanisms are complex and include the presence of an arrhythmogenic substrate, cardiac fibrosis and electrical remodeling. Aldosterone is a key component in this process. We hypothesize that perioperative mineralocorticoid receptor (MR) blockade may decrease the POAF incidence in patients with a left ventricular ejection fraction (LVEF) ≥50% who are referred for CABG with or without aortic valve replacement (AVR).

STUDY DESIGN

The ALDOCURE trial (NCT03551548) will be a multicenter, randomized, double-blind, placebo-controlled trial testing the superiority of a low-cost MR antagonist (MRA, spironolactone) on POAF in 1500 adults referred for on-pump elective CABG surgery with or without AVR, without any history of heart failure or atrial arrhythmia. The primary efficacy end point is the occurrence of POAF from randomization to within 5 days after surgery, assessed in a standardized manner. The main secondary efficacy end points include the following: postoperative AF occurring within 5 days after cardiac surgery, perioperative myocardial injury, major cardiovascular events and death occurring within 30 days of surgery, hospital and intensive care unit length of stay, need for readmission, LVEF at discharge and significant ventricular arrhythmias within 5 days after surgery. Safety end points, including blood pressure, serum potassium levels and renal function, will be monitored regularly throughout the trial duration.

CONCLUSION

The ALDOCURE trial will assess the effectiveness of spironolactone in addition to standard therapy for reducing POAF in patients undergoing CABG.

CLINICAL TRIAL REGISTRATION

NCT03551548.

Inhibitory Effects of Oxymatrine on Transdifferentiation of Neonatal Rat Cardiac Fibroblasts to Myofibroblasts Induced by Aldosterone via Keap1/Nrf2 Signaling Pathways In Vitro

Background

Oxymatrine (OMT), a quinolizidine alkaloid derived from the traditional Chinese herb Radix Sophorae flavescentis, has widely reported pharmacological efficacy in treating cardiovascular dysfunction-related diseases. However, the underlying mechanism has been unclear. Here, we investigated the potential inhibitory effects and mechanism of OMT on transdifferentiation of cardiac fibroblast to myofibroblasts induced by aldosterone in vitro.

Material/Methods

The cardiac fibroblasts (CFBs) proliferation and migration capacity were evaluated by MTT assay, cell cycle assay, and scratch analysis, respectively. The protein expression of the Nrf2/Keap1 signal pathway, FN, Collagen I, Collagen III, α-SMA, CTGF, and mineralocorticoid receptor (MR) protein was detected by Western blot analysis. The mRNA expression of Nrf2 was detected by qRT-PCR. Immunofluorescence staining was used to observe the expression of α-SMA protein. Nrf2 siRNA was used to explore the role of Nrf2 in OMT-treated CFBs. GSH, SOD, and MDA levels and hydroxyproline content were measured by colorimetric assay with commercial kits. The DCFH-DA fluorescent probe was used to assess cellular ROS levels.

Results

OMT and Curcumin (an Nrf2 agonist) attenuated aldosterone (ALD)-induced proliferation and migration in CFBs, as well as the fibrosis-associated protein expression levels. Moreover, OMT activated Nrf2 and promoted the nucleus translocation of Nrf2. OMT alleviated the elevated levels of α-SMA, Collagen I, Collagen III, and CTGF, which were abrogated by the Nrf2 siRNA transfection. We also found that OMT decreased oxidative stress levels.

Conclusions

Our results confirm that OMT alleviates transdifferentiation of cardiac fibroblasts to myofibroblasts induced by aldosterone via activating the Nrf2/Keap1 pathway in vitro.

Aldosterone induces renal fibrosis by promoting HDAC1 expression, deacetylating H3K9 and inhibiting klotho transcription

Aldosterone has an important role in the progression of renal fibrosis. In the present study, the concentration of aldosterone and klotho (KL) in the serum of patients with chronic kidney disease (CKD) were analyzed. A negative correlation was observed between aldosterone and KL, suggesting that KL may serve a protective role in CKD. Subsequently, an aldosterone‑induced CKD mouse model was established using a single nephrectomy and subcutaneous osmotic pump with aldosterone and 1% high‑salt drinking water. It was demonstrated that fibronectin 1 (Fn1) expression levels were higher in high aldosterone mice, whereas KL expression levels were low. In addition, the results demonstrated that histone deacetylase 1 (HDAC1) protein expression levels were upregulated in the renal distal convoluted tubules of high aldosterone mice, whereas acetylated H3K9 (H3K9Ac) was significantly downregulated. To determine the transcriptional activation status, chromatin immunoprecipitation polymerase chain reaction (PCR) was used to validate binding of H3K9Ac to the KL gene promoter site. It was revealed that the binding product of the KL promoter could be PCR‑amplified at the H3K9Ac site from wild‑type and low aldosterone mice; however, amplification of the binding product was not observed in high aldosterone mice. In conclusion, aldosterone significantly inhibited H3K9 acetylation by upregulating HDAC1 protein expression levels in the renal distal convoluted tubule cells, resulting in its inability to bind to the KL promoter, loss of transcription of the KL gene and increased expression of the renal fibrosis gene, Fn1.

Cardiac effects of cigarette tobacco smoking in rat model of diabetes

AIMS

Tobacco smoking is considered a global health issue, contributing to increased risk of cardiovascular disease (CVD) and diabetes (DM). We aimed to assess effects of cigarette smoking on cardiac inflammation, oxidative stress and fibrosis in rat model of streptozotocin (STZ)-induced diabetes.

MAIN METHODS

Adults Wistar rats were assigned into control (fresh air, intraperitoneal injection (i.p) of citrate buffer), cigarette smoking (1 h daily for 4 weeks, i.p citrate buffer), DM (35 STZ mg/kg single i.p, fresh air), and DM + Smoking groups for 4 weeks. Cardiac biomarkers of oxidative stress, inflammation, and fibrosis were evaluated.

KEY FINDINGS

STZ-induced diabetes as documented by the persistent increase in blood glucose. Relative to control, a significant decrease in body weight was observed in diabetic groups paralleled with increased heart to body weight ratio and systolic blood pressure in all groups. Levels of total nitrite, thiobarbituric acid substances, endothelin -1, interleukin-6 and myeloperoxidase were increased in the DM, Smoking and DM + Smoking groups without changes in C-reactive protein. Cardiac levels of GSH were increased in Smoking groups whereas activities of catalase and superoxide dismutase increased in DM, Smoking and DM + Smoking groups. DM but not smoking increased cardiac fibrosis with a parallel increase in transforming growth factor beta. Cardiac levels of matrix metalloproteinase-2 were elevated in Smoking groups and decreased in DM.

SIGNIFICANCE

Exposure to cigarette smoke may increase risk of CVD in DM by increased cardiac oxidative stress and inflammation. Smoking was associated with increased oxidant enzymes and metalloproteinase-2 probably to prevent cardiac fibrosis.

Oxidative stress and atrial fibrillation: an update

Atrial remodelling involves electrophysiological and structural abnormalities that promote the development and perpetuation of atrial fibrillation. Experimental and clinical data indicate that oxidative stress is implicated in the pathophysiology of atrial remodelling. The mechanistic links between atrial remodelling and oxidative stress are complex with several underlying diseases and conditions may affect these pathways. Therefore, the development of antioxidant interventions in this setting remains difficult. Besides classical antioxidant compounds, several agents with pleiotropic effects, including anti-inflammatory and antioxidant, have been tested in experimental and clinical settings with variable results. Strategies applying conventional antioxidants in specific situations such as postoperative atrial fibrillation show beneficial effects, especially the two-step regimen of antioxidants combination. Of note, there are limited data on the development of strategies that target specific sources of reactive oxygen species implicated in atrial remodelling. Lifestyle, diet, and risk factors modification is a complementary promising approach. This updated review provides a concise and critical overview of all available data regarding oxidative stress and its modulation in atrial fibrillation. Future directions on this exciting field are also discussed.

Mineralocorticoid Receptor Antagonism in Patients With Atrial Fibrillation: Findings From the ORBIT-AF (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation) Registry

Background

Mineralocorticoid receptor antagonist (MRA) therapy may be beneficial to patients with atrial fibrillation (AF), but little is known about their use in patients with AF and subsequent outcomes.

Methods and Results

In order to better understand MRA use and subsequent outcomes, we performed a retrospective cohort study of the contemporary ORBIT‐AF (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation) registry. AF progression and cardiovascular outcomes were compared using propensity‐matched Cox proportional hazards modeling according to MRA use at baseline and new MRA use at follow‐up versus patients with no MRA use. Among 7012 patients with nonpermanent AF, 320 patients were taking MRA at enrollment, and 416 patients initiated MRA use during follow‐up. The mean patient age was 72.5 years, 56.3% were men, and 70.4% had paroxysmal AF. Among all patients taking MRAs, 434 (59.0%) had heart failure, 655 (89.0%) had hypertension, and 380 (51.6%) had both. After adjustment, new MRA use was not associated with reduced AF progression (hazard ratio, 1.18; 95% confidence interval, 0.88–1.58; P=0.27) but showed a trend towards lower risk of stroke, transient ischemic attack, or systemic embolism (hazard ratio, 0.17; 95% confidence interval, 0.02–1.23; P=0.08). Results were similar for a comparison of new MRA users and baseline MRA users compared with nonusers.

Conclusions

In community‐based outpatients with AF, the majority of MRA use was for heart failure and hypertension. MRA use also trended towards lower adjusted stroke risk. Future studies should test the hypothesis that MRA use may decrease the risk of stroke in patients with AF.

Awareness of physicians and pharmacists of aldosterone antagonists in heart failure and myocardial infarction in Jordan

Objective:

to evaluate physicians and clinical pharmacists’ awareness and practices regarding use of aldosterone antagonists in heart failure (HF) and post-myocardial infarction (MI).

Methods:

First, we reviewed the prescription of aldosterone antagonists among 408 patients presenting to the cardiology clinic at a major hospital in Jordan. Second, physicians and pharmacists working in cardiovascular departments completed a questionnaire related to use of aldosterone antagonists in HF and post-MI.

Results:

Thirty patients (7.59%) were eligible for aldosterone antagonist; only 4 received them at discharge (13.3%). The survey was completed by 153 professionals (response rate 76.12%). About 72.1% of participants were aware of studies regarding use of aldosterone antagonists post-MI and in HF. Moreover, 10.45%/53.6% of participants strongly agreed/agreed that these agents are useful in normotensive post-MI and HF patients. Spironolactone was the most prescribed drug by 92.1% of participants. About 41.8% of participants reported use of spironolactone in post-MI and HF. With respect to guidelines, only 39.2% of participants agreed that adding spironolactone to standard therapy in HF is recommended, and 48.3% agreed on adding it directly post-MI. Clinical pharmacists and cardiologists were generally more aware of guidelines than pharmacists, cardiac surgeons and residents/fellows.

Conclusions:

there is an under-use of aldosterone antagonists in HF and post-MI patients, and a lack of detailed awareness of current guidelines among health care providers. Dissemination of evidence-based guidelines and usage protocols may improve management of post-MI and HF.

Preoperative plasma aldosterone and the risk of atrial fibrillation after coronary artery bypass surgery: a prospective cohort study

OBJECTIVE

Postoperative atrial fibrillation (POAF) is associated with poor outcomes after coronary artery bypass graft (CABG) surgery. We aimed to assess the additional value of preoperative plasma aldosterone levels, a biomarker promoting proarrhythmic and profibrotic pathways, for predicting POAF after CABG.

METHODS

We conducted a prospective cohort study involving consecutive patients with left ventricular ejection fraction (LVEF) more than 50% requiring elective CABG in our university hospital. Plasma aldosterone levels, two-dimensional echocardiography including left atrial strain analysis and galectin-3 (Gal-3) examination were assessed before cardiac surgery. The primary endpoint was the occurrence of POAF within 30 days after surgery.

RESULTS

POAF occurred in 34 (24.8%) out of the 137 included patients. Compared with controls, patients experiencing POAF were significantly older (73 years old ± 8 vs 65 ± 11, P < 0.001) and had higher preoperative plasma aldosterone levels [183 pmol/l (interquartile range 138-300) vs 143 pmol/l (interquartile range 96.5-216.5), P < 0.01]. Age [odds ratio (OR), 1.088; 95% confidence interval (CI) (1.038-1.140); P = 0.0004] and plasma aldosterone levels [OR, 1.007; 95% CI (1.003-1.012); P = 0.0013] were independently associated with POAF in multivariate analysis and could therefore be combined to predict the occurrence of POAF ['Aldoscore', OR, 2.7; 95% CI (1.7-4.3); P < 0.0001]. Reverse transcriptase PCR analysis performed on right atrial appendage and plasma examination revealed that Gal-3 was activated in POAF patients.

CONCLUSION

We developed the preoperative 'Aldoscore' for POAF risk stratification among patients with preserved LVEF requiring elective CABG. This new tool may be helpful to identify good responders to interventions targeting the proarrhythmic and profibrotic pathways of aldosterone.

Atrial Fibrillation Ablation

The prevalence of atrial fibrillation (AF) has risen significantly over the past two decades. Catheter ablation is an increasingly utilized treatment strategy and has evolved significantly over the same time period. Successful ablation improves patient symptoms, reduces stroke risk, and can preserve or improve cardiac function. Recurrences following ablation can occur, particularly in patients with persistent AF. Procedural efficacy can best be improved through continued advancements in ablation technology and strategy, better understanding of the mechanisms of AF initiation and perpetuation, and rigorous integration of ablation into a multidisciplinary AF management approach.

Effect of ramipril/hydrochlorothiazide and ramipril/canrenone combination on atrial fibrillation recurrence in hypertensive type 2 diabetic patients with and without cardiac autonomic neuropathy

INTRODUCTION

The aim of this study was to compare the effect of ramipril/canrenone versus ramipril/hydrochlorothiazide (HCTZ) combination on atrial fibrillation (AF) recurrence in type 2 diabetic hypertensives with and without cardiac autonomic neuropathy (CAN).

MATERIAL AND METHODS

A total of 289 hypertensive type 2 diabetic patients, 95 with CAN, in sinus rhythm but with at least two episodes of AF in the previous 6 months were randomized to ramipril 5 mg plus canrenone 50 mg (titrated to 10/100 mg) or to ramipril 5 mg plus HCTZ 12.5 mg (titrated to 10/25 mg) or to amlodipine 5 mg (titrated to 10 mg) for 1 year. Clinic blood pressure (BP) and a 24-h ECG were evaluated monthly. Patients were asked to report any episode of symptomatic AF and to perform an ECG as early as possible. Serum procollagen type I carboxy-terminal peptide (PIP) and carboxy-terminal telopeptide of collagen type I (CITP) were evaluated before and after each treatment period.

RESULTS

Blood pressure was similarly and significantly reduced by all treatments. A total of 51% of patients with amlodipine had a recurrence of AF, as did 31% of patients with ramipril/HCTZ (p < 0.05 vs. amlodipine) and 13% of patients with ramipril/canrenone (p < 0.01 vs. amlodipine and p < 0.05 vs. ramipril/HCTZ). A similar trend was found in diabetic patients with CAN. Both combinations reduced PIP and increased CITP, but the effects of ramipril/canrenone were significantly more marked.

CONCLUSIONS

These findings suggest that in type 2 diabetic hypertensives, ramipril/canrenone treatment was more effective than ramipril/HCTZ in reducing AF recurrence. This could be related to the greater improvement in cardiac fibrosis.

Oxidant and Inflammatory Mechanisms and Targeted Therapy in Atrial Fibrillation: An Update

Atrial fibrillation (AF) is an important cause of stroke and risk factor for heart failure and death. Current pharmacologic treatments for AF have limited efficacy, and treatments that more directly target the underlying causes of AF are needed. Oxidant stress and inflammatory activation are interrelated pathways that promote atrial electrical and structural remodeling, leading to atrial ectopy, interstitial fibrosis, and increased stroke risk. This review evaluates the impact of common stressors on atrial oxidant stress and inflammatory activation and the contribution of these pathways to atrial remodeling. Recent studies suggest that integrated efforts to target the underlying risk factors, rather than the AF per se, may have a greater impact on health and outcomes than isolated efforts focused on the electrical abnormalities.

Emerging Roles of the Mineralocorticoid Receptor in Pathology: Toward New Paradigms in Clinical Pharmacology

The mineralocorticoid receptor (MR) and its ligand aldosterone are the principal modulators of hormone-regulated renal sodium reabsorption. In addition to the kidney, there are several other cells and organs expressing MR, in which its activation mediates pathologic changes, indicating potential therapeutic applications of pharmacological MR antagonism. Steroidal MR antagonists have been used for decades to fight hypertension and more recently heart failure. New therapeutic indications are now arising, and nonsteroidal MR antagonists are currently under development. This review is focused on nonclassic MR targets in cardiac, vascular, renal, metabolic, ocular, and cutaneous diseases. The MR, associated with other risk factors, is involved in organ fibrosis, inflammation, oxidative stress, and aging; for example, in the kidney and heart MR mediates hormonal tissue-specific ion channel regulation. Genetic and epigenetic modifications of MR expression/activity that have been documented in hypertension may also present significant risk factors in other diseases and be susceptible to MR antagonism. Excess mineralocorticoid signaling, mediated by aldosterone or glucocorticoids binding, now appears deleterious in the progression of pathologies that may lead to end-stage organ failure and could therefore benefit from the repositioning of pharmacological MR antagonists.

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.

Dronedarone does not affect infarct volume as assessed by magnetic resonance imaging in a porcine model of myocardial infarction

Dronedarone has been demonstrated to be harmful in patients with recent decompensated heart failure. Furthermore, a PALLAS study reported that dronedarone therapy increases mortality rates in patients with permanent atrial fibrillation. Although a pathophysiological explanation for these finding remains to be elucidated, the long term effects of dronedarone on myocardial structure and stability have been suggested. The aim of the present study was to determine whether dronedarone therapy affects left ventricular (LV) function in a chronic model of myocardial infarction (MI). An anterior MI was induced in 16 pigs. Of these animals, eight pigs were then treated with dronedarone for 1 week prior to, and 4 weeks following MI, the remaining pigs served as controls. LV angiography was performed 4 weeks after MI to determine the LV ejection fraction (LVEF). A post‑mortem magnetic resonance imaging scan of the LV was then performed on the two groups (n=6) to determine the volume and size of the induced MI. Dronedarone therapy did not affect systemic and intracardiac hemodynamic parameters or LVEF during the follow‑up assessment. Of note, dronedarone had no negative effect on the total infarct volume and size and did not induce lethal proarrhythmic effects following the induced anterior MI. Therefore, the results suggested that dronedarone did not increase the volume or size of induced anterior MI and did not affect LV performance. Thus, dronedarone therapy was observed to be safe in a porcine model of anterior MI.

Renal denervation suppresses atrial fibrillation in a model of renal impairment

Background

A close association exists between renal impairment (RI) and atrial fibrillation (AF) occurrence. Increased activity of the sympathetic nervous system (SNS) may contribute to the development of AF associated with RI. Renal denervation (RDN) decreases central sympathetic activity.

Objective

The main objective of the study was to explore the effects of RDN on AF occurrence and its possible mechanisms in beagles with RI.

Methods

Unilateral RI was induced in beagles by embolization of small branches of the renal artery in the right kidney using gelatin sponge granules in Model (n = 6) and RDN group (n = 6). The Sham group (n = 6) underwent the same procedure, except for embolization. Then animals in RDN group underwent radiofrequency ablation of the renal sympathetic nerve. Cardiac electrophysiological parameters, blood pressure, left ventricular end-diastolic pressure, and AF inducibility were investigated. The activity of the SNS, renin-angiotensin-aldosterone system (RAAS), inflammation and atrial interstitial fibrosis were measured.

Results

Embolization of small branches of the renal artery in the right kidney led to ischemic RI. Heart rate, P wave duration and BP were increased by RI, which were prevented or attenuated by RDN. Atrial effective refractory period was shortened and AF inducibility was increased by RI, which were prevented by RDN. Antegrade Wenckebach point was shortened, atrial and ventricular rates during AF were increased by RI, which were attenuated or prevented by RDN. Levels of norepinephrine, renin and aldosterone in plasma, norepinephrine, angiotensin II, aldosterone, interleukin-6 and high sensitivity C-reactive protein in atrial tissue were elevated, and atrial interstitial fibrosis was enhanced by RI, which were attenuated by RDN.

Conclusions

RDN significantly reduced AF inducibility, prevented the atrial electrophysiological changes in a model of RI by combined reduction of sympathetic drive and RAAS activity, and inhibition of inflammation activity and fibrotic pathway in atrial tissue.