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

Circulating aldosterone and natriuretic peptides in the general community: relationship to cardiorenal and metabolic disease

We sought to investigate the role of aldosterone as a mediator of disease and its relationship with the counter-regulatory natriuretic peptide (NP) system. We measured plasma aldosterone (n=1674; aged≥45 years old) in a random sample of the general population from Olmsted County, MN. In a multivariate logistic regression model, aldosterone analyzed as a continuous variable was associated with hypertension (odds ratio [OR]=1.75; 95% confidence interval [CI]=1.57-1.96; P<0.0001), obesity (OR=1.34; 95% CI=1.21-1.48; P<0.0001), chronic kidney disease (OR=1.39; 95% CI=1.22-1.60; P<0.0001), central obesity (OR=1.47; 95% CI=1.32-1.63; P<0.0001), metabolic syndrome (OR=1.41; 95% CI=1.26-1.58; P<0.0001), high triglycerides (OR=1.23; 95% CI=1.11-1.36; P<0.0001), concentric left ventricular hypertrophy (OR=1.22; 95% CI=1.09-1.38; P=0.0007), and atrial fibrillation (OR=1.24; 95% CI=1.01-1.53; P=0.04), after adjusting for age and sex. The associations with hypertension, central obesity, metabolic syndrome, triglycerides, and concentric left ventricular hypertrophy remained significant after further adjustment for body mass index, NPs, and renal function. Furthermore, aldosterone in the highest tertile correlated with lower NP levels and increased mortality. Importantly, most of these associations remained significant even after excluding subjects with aldosterone levels above the normal range. In conclusion, we report that aldosterone is associated with hypertension, chronic kidney disease, obesity, metabolic syndrome, concentric left ventricular hypertrophy, and lower NPs in the general community. Our data suggest that aldosterone, even within the normal range, may be a biomarker of cardiorenal and metabolic disease. Further studies are warranted to evaluate a therapeutic and preventive strategy to delay the onset and progression of disease, using mineralocorticoid antagonists or chronic NP administration in high-risk subjects identified by plasma aldosterone.

Establishment of a model of renal impairment with mild renal insufficiency associated with atrial fibrillation in canines

Background

Chronic kidney disease and occurrence of atrial fibrillation (AF) are closely related. No studies have examined whether renal impairment (RI) without severe renal dysfunction is associated with the occurrence of AF.

Methods

Unilateral RI with mild renal insufficiency was induced in beagles by embolization of small branches of the renal artery in the left kidney for 2 weeks using gelatin sponge granules in the model group (n = 5). The sham group (n = 5) underwent the same procedure, except for embolization. Parameters associated with RI and renal function were tested, cardiac electrophysiological parameters, blood pressure, left ventricular pressure, and AF vulnerability were investigated. The activity of the sympathetic nervous system, renin-angiotensin-aldosterone system, inflammation, and oxidative stress were measured. Histological studies associated with atrial interstitial fibrosis were performed.

Results

Embolization of small branches of the renal artery in the left kidney led to ischemic RI with mild renal insufficiency. The following changes occurred after embolization. Heart rate and P wave duration were increased. Blood pressure and left ventricular systolic pressure were elevated. The atrial effective refractory period and antegrade Wenckebach point were shortened. Episodes and duration of AF, as well as atrial and ventricular rate during AF were increased in the model group. Plasma levels of norepinephrine, renin, and aldosterone were increased, angiotensin II and aldosterone levels in atrial tissue were elevated, and atrial interstitial fibrosis was enhanced after 2 weeks of embolization in the model group.

Conclusions

We successfully established a model of RI with mild renal insufficiency in a large animal. We found that RI with mild renal insufficiency was associated with AF in this model.

Atrial Fibrillation and Its Association with Endocrine Disorders

Atrial Fibrillation (AF) is the most common arrhythmia affecting millions of people and the number is rising, it is therefore important to understand the risk factors causing AF. Risk factors such as hypertension, heart failure, coronary heart disease, and type 2 diabetes mellitus increase the risk of AF, however, the underlying etiology in a majority of patients remains elusive. Many of the endocrine disorders have been implicated in causing AF and an in depth knowledge of these disorders helps in early diagnosis and treatment. Due to the high prevalence of AF and its complications, it is therefore important to recognize these risk factors and have a low threshold for suspicion while other common causes are being excluded. In this review we summarize the issues related to AF and endocrine disorders. A better understanding of the relationship may lead to the development of the primary preventive strategies, fostering a more preventive and predictive approach that may result in decreased incidence of AF and its associated complications and provide personalized treatment options. For this review we carried out a search of Pubmed, the words or combination of words we used for our search include Endocrine disorders, metabolic disorders, Dyslipidemia, Diabetes mellitus type 2, Vitamin D, Hyperthyroidism, Primary aldosteronism, Pheochromocytoma, Obesity, Hypercalcemia, Hypogonadism, Medications, and Atrial fibrillation. We also retrieved articles from the references of retrieved articles.