Does the ratio of serum aldosterone to plasma renin activity predict the efficacy of diuretics in hypertension? Results of RENALDO

Primary Aldosteronism and Drug Resistant Hypertension: A "Chicken-Egg" Story

Drug-resistant arterial hypertension (RH) is a major risk factor for cardiovascular disease, often due to overlooked underlying causes. Identification of such causes poses significant clinical challenges. In this setting, primary aldosteronism (PA) is a frequent cause of RH and its prevalence in RH patients is likely higher than 20%.The pathophysiological link between PA and the development and maintenance of RH involves target organ damage and the cellular and extracellular effects of aldosterone excess that promote pro-inflammatory and pro-fibrotic changes in the kidney and vasculature.The feasibility of adrenal vein sampling in PA patients with RH, and the clinical benefit achieved by adrenalectomy, further emphasize the need to implement systematic screening for this common form of secondary hypertension in the management of a high-risk population as RH patients.: We herein review the current knowledge of the factors that contribute to the RH phenotype with a focus on PA and discuss the issues regarding the screening for PA in this setting and the therapeutic approaches (surgical and medical) aimed at resolving RH caused by PA.

Mineralocorticoid Receptor Antagonists Cause Natriuresis in the Absence of Aldosterone

BACKGROUND

MR (mineralocorticoid receptor) antagonists are recommended for patients with resistant hypertension even when circulating aldosterone levels are not high. Although aldosterone activates MR to increase epithelial sodium channel (ENaC) activity, glucocorticoids also activate MR but are metabolized by 11βHSD2 (11β-hydroxysteroid dehydrogenase type 2). 11βHSD2 is expressed at increasing levels from distal convoluted tubule (DCT) through collecting duct. Here, we hypothesized that MR maintains ENaC activity in the DCT2 and early connecting tubule in the absence of aldosterone.

METHODS

We studied AS (aldosterone synthase)-deficient (AS^-/-) mice, which were backcrossed onto the same C57BL6/J strain as kidney-specific MR knockout (KS-MR^-/-) mice. KS-MR^-/- mice were used to compare MR expression and ENaC localization and cleavage with AS^-/- mice.

RESULTS

MR was highly expressed along DCT2 through the cortical collecting duct (CCD), whereas no 11βHSD2 expression was observed along DCT2. MR signal and apical ENaC localization were clearly reduced along both DCT2 and CCD in KS-MR^-/- mice but were fully preserved along DCT2 and were partially reduced along CCD in AS^-/- mice. Apical ENaC localization and ENaC currents were fully preserved along DCT2 in AS^-/- mice and were not increased along CCD after low salt. AS^-/- mice exhibited transient Na⁺ wasting under low-salt diet, but administration of the MR antagonist eplerenone to AS^-/- mice led to hyperkalemia and decreased body weight with higher Na⁺ excretion, mimicking the phenotype of MR^-/- mice.

CONCLUSIONS

Our results provide evidence that MR is activated in the absence of aldosterone along DCT2 and partially CCD, suggesting glucocorticoid binding to MR preserves sodium homeostasis along DCT2 in AS^-/- mice.

Retrospective cohort study to characterise the blood pressure response to spironolactone in patients with apparent therapy-resistant hypertension using electronic medical record data

OBJECTIVE

Identify blood pressure (BP) response to spironolactone in patients with apparent therapy-resistant hypertension (aTRH) using electronic medical records (EMRs) in order to estimate response in a real-world clinical setting.

DESIGN

Developed an algorithm to determine BP and electrolyte response to spironolactone for use in a retrospective cohort study.

SETTING

An academic medical centre in Nashville, Tennessee.

POPULATION

Patients with aTRH prescribed spironolactone.

MAIN OUTCOME MEASURES

Baseline BP and BP response, determined as the change in mean systolic BP (SBP) and diastolic BP (DBP) following spironolactone initiation. Additional response measures were serum sodium, potassium and creatinine, estimated glomerular filtration rate, haemoglobin A1c (HbA1c), glucose, high-density lipoprotein, low-density lipoprotein and triglycerides. Demographic characteristics included race, age, gender, body mass index (BMI), diabetes mellitus, chronic kidney disease stage 3, ischaemic heart disease and smoking.

RESULTS

The mean decreases in SBP and DBP were 8.1 and 3.4 mm Hg, consistent with clinical trial data. Using a mean decrease in SBP of 5 mm Hg or in DBP of 2 mm Hg to define 'responders', 30.3% of patients did not respond. In univariable analyses, responders had higher BMI, baseline SBP, DBP, sodium and HbA1c, and lower creatinine. In multivariable analysis, responders were older and had significantly higher BMI and baseline SBP and DBP, and lower potassium. Increases in potassium and creatinine following spironolactone were larger in responders. When BP was evaluated as a continuous variable, decreases in SBP and DBP correlated with baseline BP, decrease in sodium and increases in potassium and creatinine following spironolactone. The decrease in SBP was associated with decreasing glucose in European Americans.

CONCLUSIONS

We developed an algorithm to assess BP response to a commonly prescribed medication for aTRH using EMRs. Electrolyte changes associated with the BP response to spironolactone are consistent with its mechanism of action of blocking the mineralocorticoid receptor and decreasing epithelial sodium channel activity.

Is the plasma aldosterone-to-renin ratio associated with blood pressure response to treatment in general practice?

BACKGROUND

Individualized antihypertensive treatment based on specific biomarkers such as renin may lead to more effective blood pressure control in patients with newly diagnosed essential hypertension. Recent studies suggested that the plasma aldosterone-to-renin ratio (ARR) may also be a candidate predictor for this purpose.

OBJECTIVE

To assess whether the ARR is associated with the blood pressure response to antihypertensive treatment in patients with newly diagnosed hypertension.

METHODS

In this prospective cohort study in primary care, we determined the ARR in patients with newly diagnosed hypertension prior to starting treatment. Treatment was categorized in five groups: no medication, use of angiotensin-converting-enzyme inhibitor or angiotensin receptor blocker, use of calcium channel blocker, use of diuretic, or use of beta blocker. We examined the relation between the ARR and blood pressure response within 1 year of treatment, taking into account the type of antihypertensive treatment and adjusting for gender, age, baseline blood pressure, and comorbidity.

RESULTS

Out of 304 patients, we used 947 measurements (727 no medication, 220 medication) for analysis. There was no association between the ARR and the response in blood pressure, and this applied to each treatment group. Target blood pressure, defined as systolic blood pressure <140 mmHg, was reached in 31% of patients. There was no association between the ARR and reaching target blood pressure (OR 1.002, 95% CI 0.983-1.022).

CONCLUSION

The ARR is not associated with the response in blood pressure within 1 year of antihypertensive treatment in primary care.

The Use of Precision Medicine to Manage Obstructive Sleep Apnea Treatment in Patients with Resistant Hypertension: Current Evidence and Future Directions

PURPOSE OF REVIEW

The significant prevalence of resistant hypertension (RH) and the high cardiovascular risk of the population of patients with RH have indicated the necessity to identify its main causes. Among these, obstructive sleep apnea (OSA) is considered the most well-established cause.

RECENT FINDINGS

In recent years, several studies have shown a beneficial effect of continuous positive airway pressure (CPAP) treatment on blood pressure (BP), but this effect exhibits great variability. The diagnosis and management of OSA in patients with RH suggest a clinical option for a phenotype of patients for whom therapeutic strategies are limited to pharmaceutical therapy and renal denervation. However, the great variability in the CPAP response has increased the necessity to develop instruments to identify patients who could benefit from a treatment that reduces BP. Application of precision medicine to these patients should be considered as a first-line intervention to avoid the prescription of ineffective treatments and excessive consumption of pharmacological drugs that do not ameliorate the cardiovascular risk.

[Benefits of spironolactone as the optimal treatment for drug resistant hypertension. Pathway-2 trial review]

Pathway-2 is the first randomised, double-blind and crossover trial that compares spironolactone as a fourth drug with alfa-blocker, beta-blocker and placebo. This study shows that spironolactone is the drug with more possibilities of success for the management of patients with difficult-to-treat hypertension in patients with a combination of three drugs and poor control. The results validate the widespread treatment with mineralocorticoid receptor antagonists in resistant hypertension.

Serum metabolites predict response to angiotensin II receptor blockers in patients with diabetes mellitus

Background

Individual patients show a large variability in albuminuria response to angiotensin receptor blockers (ARB). Identifying novel biomarkers that predict ARB response may help tailor therapy. We aimed to discover and validate a serum metabolite classifier that predicts albuminuria response to ARBs in patients with diabetes mellitus and micro- or macroalbuminuria.

Methods

Liquid chromatography-tandem mass spectrometry metabolomics was performed on serum samples. Data from patients with type 2 diabetes and microalbuminuria (n = 49) treated with irbesartan 300 mg/day were used for discovery. LASSO and ridge regression were performed to develop the classifier. Improvement in albuminuria response prediction was assessed by calculating differences in R² between a reference model of clinical parameters and a model with clinical parameters and the classifier. The classifier was externally validated in patients with type 1 diabetes and macroalbuminuria (n = 50) treated with losartan 100 mg/day. Molecular process analysis was performed to link metabolites to molecular mechanisms contributing to ARB response.

Results

In discovery, median change in urinary albumin excretion (UAE) was −42 % [Q1–Q3: −69 to −8]. The classifier, consisting of 21 metabolites, was significantly associated with UAE response to irbesartan (p < 0.001) and improved prediction of UAE response on top of the clinical reference model (R² increase from 0.10 to 0.70; p < 0.001). In external validation, median change in UAE was −43 % [Q1–Q35: −63 to −23]. The classifier improved prediction of UAE response to losartan (R² increase from 0.20 to 0.59; p < 0.001). Specifically ADMA impacting eNOS activity appears to be a relevant factor in ARB response.

Conclusions

A serum metabolite classifier was discovered and externally validated to significantly improve prediction of albuminuria response to ARBs in diabetes mellitus.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0960-3) contains supplementary material, which is available to authorized users.

Urinary sodium excretion predicts blood pressure response to spironolactone in patients with resistant hypertension independent of aldosterone status

OBJECTIVE

Resistant hypertension (RHTN), blood pressure (BP) at least 140/90 mmHg despite using at least three different medications, including a diuretic, is associated with high dietary sodium and hyperaldosteronism. Mineralocorticoid receptor antagonists are recommended for treatment of RHTN, however, BP response to these agents varies widely. In the current analysis, we assessed predictors of BP response to spironolactone in patients with RHTN.

METHODS

We retrospectively evaluated the BP response to adding spironolactone 12.5-25 mg to existing medications. A favorable BP response was defined as a reduction in SBP of at least 10 mmHg. Tested variables included baseline characteristics and biochemical parameters.

RESULTS

A total of 79 patients with RHTN were included in the analysis. Evaluated patients were more likely women (53.2%) and African-American (55.8%); were generally obese (76%) and were prescribed an average of four antihypertensive medications. Baseline SBP was 153.6 ± 22.3 mmHg; addition of spironolactone resulted in a mean reduction of 15.5 ± 20.7 mmHg. Patients with high urinary sodium excretion (≥200 mEq/24 h) had a significantly greater BP reduction compared with patients with normal excretion (<200 mEq/24 h) (P = 0.008). Multivariable analysis identified 24 h urinary sodium excretion as a significant predictor of BP response (P = 0.021) after controlling for potential confounders, including primary aldosteronism.

CONCLUSION

The antihypertensive effect of spironolactone is positively related to urinary sodium excretion regardless of aldosterone status. These findings suggest that mineralocorticoid receptor antagonists may be of preferential benefit in counteracting the BP effects of high dietary sodium.

Mineralocorticoid Receptor Antagonists Therapy in Resistant Hypertension: Time to Implement Guidelines!

Despite the availability of anti-hypertensive medications with increasing efficacy up to 50% of hypertensive patients have blood pressure levels (BP) not at the goals set by international societies. Some of these patients are either not optimally treated or are non-adherent to the prescribed drugs. However, a proportion, despite adequate treatment, have resistant hypertension (RH), which represents an important problem in that it is associated to an excess risk of cardiovascular events. Notwithstanding a complex pathogenesis, an abundance of data suggests a key contribution for the mineralocorticoid receptor (MR) in RH, thus fostering a potential role for its antagonists in RH. Based on these premises randomized clinical trials aimed at testing the efficacy of MR antagonists (MRAs) in RH patients have been completed. Overall, they demonstrated the efficacy of MRAs in reducing BP and surrogate markers of target organ damage, such as microalbuminuria, either compared to placebo or to other drugs. In summary, owing to the key role of the MR in the pathogenesis of RH and on the proven efficacy of MRAs we advocate their inclusion as an essential component of therapy in patients with presumed RH. Conversely, we propose that RH should be diagnosed only in patients whose BP values show to be resistant to an up-titrated dose of these drugs.

Effect of spironolactone in resistant arterial hypertension: a randomized, double-blind, placebo-controlled trial (ASPIRANT-EXT)

This study was designed to assess the effect of the addition of low-dose spironolactone on blood pressure (BP) in patients with resistant arterial hypertension. Patients with office systolic blood pressure (SBP) >140 mm Hg or diastolic blood pressure (DBP) >90 mm Hg despite treatment with at least 3 antihypertensive drugs, including a diuretic, were enrolled in this double-blind, placebo-controlled, multicentre trial. One hundred sixty-one patients in outpatient internal medicine departments of 6 hospitals in the Czech Republic were randomly assigned to receive 25 mg of spironolactone (N = 81) or a placebo (N = 80) once daily as an add-on to their antihypertensive medication, using simple randomization. This study was registered with ClinicalTrials.gov, number NCT00524615. A nalyses were done with 150 patients who finished the follow-up (74 in the spironolactone and 76 in the placebo group). At 8 weeks, BP values were decreased more by spironolactone, with differences in mean fall of SBP of -9.8, -13.0, -10.5, and -9.9 mm Hg (P < 0.001 for all) in daytime, nighttime, and 24-hour ambulatory BP monitoring and in the office. The respective DBP differences were -3.2, -6.4, -3.5, and -3.0 mm Hg (P = 0.013, P < 0.001, P = 0.005, and P = 0.003). Adverse events in both groups were comparable. The office SBP goal <14 mm Hg at 8 weeks was reached in 73% of patients using spironolactone and 41% using placebo (P = 0.001). Spironolactone in patients with resistant arterial hypertension leads to a significant decrease of both SBP and DBP and markedly improves BP control.

What is the role of aldosterone excess in resistant hypertension and how should it be investigated and treated?

Resistant hypertension has evolved as an important global health care problem. Primary aldosteronism is one of several potentially reversible causes of resistant hypertension. Primary aldosteronism can be effectively treated, when recognized, with a mineralocorticoid receptor antagonist, such as spironolactone and eplerenone. Each of these compounds can reduce blood pressure as monotherapy or when given with a range of other antihypertensive drug classes. These compounds have distinctive pharmacokinetic and pharmacodynamic patterns that require some forethought in their use before they are prescribed. However, as the use of mineralocorticoid-blocking agents has gradually increased, the hazards inherent to use of such drugs has become more apparent. Whereas the endocrine side effects of spironolactone are in most cases little more than a cosmetic annoyance, the potassium-sparing effects of both spironolactone and eplerenone can prove fatal if sufficient degrees of hyperkalemia develop. However, for most patients the risk of developing hyperkalemia in and of itself should not discourage the prudent clinician from bringing these compounds into play. Hyperkalemia should always be considered as a likelihood in any patient receiving one or the other of these medications. As such, steps should be taken to lessen the likelihood of it occurring if therapy is being contemplated with agents in this class.

Addition of spironolactone in patients with resistant arterial hypertension (ASPIRANT): a randomized, double-blind, placebo-controlled trial

There is currently limited data on which drug should be used to improve blood pressure (BP) control in patients with resistant hypertension. This study was designed to assess the effect of the addition of 25 mg of spironolactone on BP in patients with resistant arterial hypertension. Patients with office systolic BP >140 mm Hg or diastolic BP >90 mm Hg despite treatment with at least 3 antihypertensive drugs, including a diuretic, were enrolled in this double-blind, placebo-controlled, multicenter trial. One hundred seventeen patients were randomly assigned to receive spironolactone (n=59) or a placebo (n=58) as an add-on to their antihypertensive medication, by the method of simple randomization. Analyses were done with 111 patients (55 in the spironolactone and 56 in the placebo groups). At 8 weeks, the primary end points, a difference in mean fall of BP on daytime ambulatory BP monitoring (ABPM), between the groups was -5.4 mm Hg (95%CI -10.0; -0.8) for systolic BP (P=0.024) and -1.0 mm Hg (95% CI -4.0; 2.0) for diastolic BP (P=0.358). The APBM nighttime systolic, 24-hour ABPM systolic, and office systolic BP values were significantly decreased by spironolactone (difference of -8.6, -6.6, and -6.5 mm Hg; P=0=0.011, 0.004, and 0.011 [corrected]), whereas the fall of the respective diastolic BP values was not significant (-3.0, -1.0, and -2.5 mm Hg; P=0.079, 0.405, and 0.079). The adverse events in both groups were comparable. In conclusion, spironolactone is an effective drug for lowering systolic BP in patients with resistant arterial hypertension.

Common secondary causes of resistant hypertension and rational for treatment

Resistant hypertension is defined as uncontrolled blood pressure despite the use of three antihypertensive drugs, including a diuretic, in optimal doses. Treatment resistance can be attributed to poor adherence to antihypertensive drugs, excessive salt intake, physician inertia, inappropriate or inadequate medication, and secondary hypertension. Drug-induced hypertension, obstructive sleep apnoea, primary aldosteronism, and chronic kidney disease represent the most common secondary causes of resistant hypertension. Several drugs can induce or exacerbate pre-existing hypertension, with non-steroidal anti-inflammatory drugs being the most common due to their wide use. Obstructive sleep apnoea and primary aldosteronism are frequently encountered in patients with resistant hypertension and require expert management. Hypertension is commonly found in patients with chronic kidney disease and is frequently resistant to treatment, while the management of renovascular hypertension remains controversial. A step-by-step approach of patients with resistant hypertension is proposed at the end of this review paper.

Primary aldosteronism: A contrarian view

This paper provides evidence that primary aldosteronism is likely much less common than is believed by the other authors of this collection. The basis for this contrarian view is simple: there is no way to know the true prevalence of PA because of the uncertain validity of all of the diagnostic procedures used to find and characterize this disease. Moreover, even if these uncertainties are overcome, the eventual treatment of most who have PA can be provided without the need for extensive testing and expensive treatment.

Benefits from treatment and control of patients with resistant hypertension

Resistant hypertension is commonly found in everyday clinical practice. However, the risks of resistant hypertension, as well as the benefits of treatment and control of blood pressure in patients with resistant hypertension remain vaguely clarified. Data from small clinical studies and observational cohorts suggest that patients with resistant hypertension are at increased cardiovascular risk, while control of blood pressure offers substantial benefits. It has to be noted however that data from appropriate large randomized studies are missing, and resistant hypertension remains remarkably understudied. Resistant hypertension has attracted significant scientific interest lately, as new therapeutic modalities become available. The interventional management of resistant hypertension either by carotid baroreceptor stimulation or renal sympathetic denervation is currently under investigation with promising preliminary results. This review presents available evidence regarding the benefits of treatment and control of blood pressure in patients with resistant hypertension and offers a critical evaluation of existing data in this field.

Current diagnosis and treatment of primary aldosteronism

Primary aldosteronism is more common than previously recognized but much less common than most experts in this arena have recently stated. The recognition of autonomous hyperaldosteronism is not difficult but the identification of the source of excess aldosterone requires a costly and difficult procedure. Most patients with hyperaldosteronism turn out to have bilateral adrenal hyperplasia for which medical therapy with an aldosterone blocker is indicated. Many of these patients are not hypokalemic and can safely be treated without the need for a costly and usually negative work-up.

Primary aldosteronism: an update

Primary aldosteronism (PA) is common with an estimated prevalence rate of 10% in subjects with essential hypertension and higher in those with resistant hypertension. As well as contributing to hypertension, aldosterone has detrimental effects on the heart, vasculature and kidneys as well as adverse metabolic effects leading to an excess of cardiovascular morbidity. Therefore, recognition and appropriate treatment of PA is of increasing importance. However, the diagnosis of PA and determination of subtype can be problematic. The purpose of this review is to provide an overview of the evidence supporting this increased prevalence of PA, explore the metabolic and cardiovascular consequences of aldosterone excess and discuss optimal diagnostic and therapeutic strategies of PA.