Aldosterone to renin ratio as a determinant of exercise blood pressure response in hypertensive patients

Impact of spironolactone on vascular, myocardial, and functional parameters in untreated patients with a hypertensive response to exercise

BACKGROUND

Although a hypertensive response to exercise (HRE) is associated with cardiac risk and masked hypertension (MHT), its mechanisms and appropriate treatment remain unclear. We investigated spironolactone as a treatment for abnormal vascular and myocardial stiffness in HRE.

METHODS

In this randomized, double-blind, placebo-controlled study of 115 patients (54 ± 9 years, 57% men) with an HRE (≥210/105 mm Hg in men; ≥190/105 mm Hg in women) but no prior history of hypertension or myocardial ischemia, MHT prevalence was 40%. Patients were randomized to spironolactone 25mg daily (n = 58) or placebo (n = 57) and underwent evaluation at baseline and 3 months with exercise echocardiography, VO2max, pulse wave velocity (PWV), exercise and central blood pressure (BP), and 24-hour ambulatory BP. Changes in left ventricular mass index (LVMI), Doppler-derived E/em ratio (LV filling pressure), and myocardial strain were assessed.

RESULTS

Baseline 24-hour systolic BP (SBP) was 133 ± 10 mm Hg and peak-exercise SBP was 219 ± 16 mm Hg. Peak systolic strain (0.3 ± 3.6% vs. -0.1 ± 3.2, P = 0.56), E/em (-1.1 ± 2.3 vs. -0.6 ± 1.7, P = 0.30), VO(2max) (0.4 ± 4.9 vs. -0.9 ± 4.1 ml/kg/min, P = 0.15), and adjusted PWV did not significantly change with treatment, despite reduction in exercise SBP, 24-hour SBP, and LVMI. The change in exercise E/em was of borderline significance (-0.3 ± 2.4 vs. 0.8 ± 2.8, P = 0.06) and became significant after adjustment for baseline differences (P = 0.01). Patients with higher LVMI significantly increased VO(2max) (1.1 ± 5.6 vs. -2.4 ± 4.4 ml/kg/min, P < 0.05) and reduced exercise E/e(m) (-0.7 ± 2.7 vs. 1.9 ± 2.8, P < 0.05).

CONCLUSIONS

In HRE patients without previous hypertension, short-term spironolactone reduced exercise BP, 24-hour ambulatory BP, LVMI, and E/e(m) but did not significantly alter exercise capacity or myocardial strain.

Blood pressure and plasma renin activity responses to different strategies to inhibit the renin-angiotensin-aldosterone system during exercise

OBJECTIVE

The effect of two different strategies for renin-angiotensin-aldosterone system (RAAS) blockade; direct renin inhibition (DRI) versus angiotensin receptor blockade (ARB) on blood pressure (BP) and plasma renin activity (PRA) was compared during exercise.

METHODS

Hypertensive adults were randomised to aliskiren (300 mg once daily, n=33) or valsartan (320 mg once daily, n=35). BP and PRA were measured during treadmill exercise (Bruce protocol), at baseline, end of treatment (eight weeks), and after treatment withdrawal (48 hours after last dose).

RESULTS

After eight weeks treatment, Aliskiren inhibited PRA (>80%) at rest and during exercise, with inhibition remaining undiminished 48 hours after treatment withdrawal. In contrast, valsartan increased PRA at rest, and more-so during exercise (>400%). Angiotensin receptor blockade, as indicated by PRA increase, was reduced, 48 hours after valsartan treatment withdrawal, suggesting more sustained RAAS blockade with aliskiren. Despite divergent effects on PRA, similar exercise-induced changes in BP were seen. The primary outcome, the rise in systolic BP from rest to peak exercise (baseline to after treatment withdrawal) did not differ between treatments (p=0.25).

CONCLUSION

Measurement of PRA is a more sensitive index of RAAS blockade than the BP response during exercise. Furthermore, after treatment withdrawal, aliskiren provides more sustained RAAS inhibition than valsartan at rest and during exercise.

Stress reactivity in patients with workplace hypertension

Aim. To investigate the specific features of stress reactivity and diagnostic potential of psycho-emotional tests for identification of the patients with workplace arterial hypertension (WPAH). Material ad methods. The study included 197 patients with WPAH and 132 subjects with essential AH (EAH). All participants underwent blood pressure monitoring (BPM) during work and leisure hours and stress reactivity assessment (count test). Results. In WPAH and EAH patients, the count test resulted in increased systolic (SBP), diastolic (DBP) BP, and heart rate (HR) (р<0,001), which was an evidence of stress-related functional cardiovascular reaction. In subjects with new-onset WPAH, compared to EAH patients, the SBP and HR increases were greater by 7,9 mm Hg (р<0,005) and 4,3 bpm (р<0,001), respectively. In patients with long-term EAH, SBP increase was greater by 3,4 mm Hg (p=0,03), with a halved HR increase (p<0,001). In healthy controls and AH patients, the differences between baseline levels of SBP and DBP, peak levels during the count test, and BMP levels for work hours were comparable. Conclusion. The patients at early WPAH stages were characterized by increased cardiovascular reaction to acute induced psycho-emotional stress. At the later WPAH stages, BP reactivity was reduced. The cont test could be used as a screening tool in patients with undiagnosed WPAH.

Efficacy of exercise, losartan, enalapril, atenolol and rilmenidine in subjects with blood pressure hyperreactivity at treadmill stress test and left ventricular hypertrophy

High levels of activity of the renin-angiotensin system (RAS) and sympathetic nervous system (SNS) are related to left ventricular hypertrophy (LVH). A percentage of subjects with hyperactivity to treadmill stress test show LVH to echocardiogram. This paper aims at evaluating neurohumoral influence over these subjects by comparing drugs that block both the RAS and the SNS. In a 1-year open protocol, 195 normotensive subjects, with hyperactivity to treadmill stress test and LVH, were randomly assigned to supervised physical exercise, rilmenidine 1 mg day(-1), atenolol 50 mg day(-1), enalapril 10 mg day(-1) or losartan 50 mg day(-1). Changes in left ventricular mass index (LVMI), measured by means of echocardiogram, were the primary end point. Changes in systolic blood pressure (SBP) at rest and peak effort were also evaluated. Enalapril significantly brought LVMI down in relation to the basal value (28.2%; n=36) similarly to losartan (26.9%; n=42); P>0.05. However, both were more efficient than physical exercise (2.9%; n=39), rilmenidine (5.1%; n=38) and atenolol (7.2%; n=40); P<0.001. There was no significant difference in SBP reduction at rest and peak effort in groups assigned to atenolol, enalapril and losartan; P>0.05. In such groups, reduction was greater than in groups assigned to physical exercise and rimenidine; P<0.001. In conclusion, drugs that block RAS were more efficient in reducing LVH than physical exercise and drugs that block SNS, and such reduction took place regardless of SBP level reduction at rest and peak effort.

Does the aldosterone:renin ratio predict the efficacy of spironolactone over bendroflumethiazide in hypertension? A clinical trial protocol for RENALDO (RENin-ALDOsterone) study

Background

High blood pressure is an important determinant of cardiovascular disease risk. Treated hypertensives do not attain a risk level equivalent to normotensives. This may be a consequence of suboptimal blood pressure control to which indiscriminate use of antihypertensive drugs may contribute. Indeed the recent ALLHAT[1]study suggests that thiazides should be given first to virtually all hypertensives. Whether this is correct or whether different antihypertensive therapies should be targeted towards different patients is a major unresolved issue, which we address in this study.

The measurement of the ratio of aldosterone: renin is used to identify hypertensive subjects who may respond well to treatment with the aldosterone antagonist spironolactone. It is not known if subjects with a high ratio have aldosteronism or aldosterone-sensitive hypertension is debated but it is important to know whether spironolactone is superior to other diuretics such as bendroflumethiazide in this setting.

Methods/design

The study is a double-blind, randomised, crossover, controlled trial that will randomise 120 hypertensive subjects to 12 weeks treatment with spironolactone 50 mg once daily and 12 weeks treatment with bendroflumethiazide 2.5 mg once daily. The 2 treatment periods are separated by a 2-week washout period. Randomisation is stratified by aldosterone: renin ratio to include equal numbers of subjects with high and low aldosterone: renin ratios.

Primary Objective – To test the hypothesis that the aldosterone: renin ratio predicts the antihypertensive response to spironolactone, specifically that the effect of spironolactone 50 mg is greater than that of bendroflumethiazide 2.5 mg in hypertensive subjects with high aldosterone: renin ratios.

Secondary Objectives – To determine whether bendroflumethiazide induces adverse metabolic abnormalities, especially in subjects with high aldosterone: renin ratios and if baseline renin measurement predicts the antihypertensive response to spironolactone and/or bendrofluazide

Discussion

The numerous deleterious effects of hypertension dictate the need for a systematic approach for its treatment. In spite of various therapies, resistant hypertension is widely prevalent. Among various factors, primary aldosteronism is an important cause of resistant hypertension and is now more commonly recognised. More significantly, hypertensives with primary aldosteronism are also exposed to various other deleterious effects of excess aldosterone. Hence treating hypertension with specific aldosterone antagonists may be a better approach in this group of patients. It may lead on to better blood pressures with fewer medications.

Effect of Aerobic Exercise Training on Renal Responses to Sodium in Hypertensives

INTRODUCTION

Aerobic exercise training has been shown to improve cardiovascular function and lower blood pressure (BP) in older adults. The exact mechanism(s) by which aerobic exercise training elicits these changes are unknown; however, it is possible that changes in renal hemodynamics may play a role.

PURPOSE

The present study was undertaken to examine the effect of aerobic exercise training on renal hemodynamics in older hypertensive individuals.

METHODS

Renal plasma flow (RPF) and glomerular filtration rate (GFR) were determined by plasma and urinary clearances of 131I-hippuran and 99mTc-DTPA after 8 d of low (20 mEq) and high (200 mEq) Na+ diets in 31 older (63 +/- 1 yr), hypertensive (152 +/- 2/88 +/- 1 mm Hg) individuals at baseline and following 6 months of aerobic exercise training (at 75% VO2max, three times a week, 40 min per session).

RESULTS

Following 6 months of aerobic exercise training, a significant increase was seen in maximal aerobic capacity (VO2max: 18.3 +/- 0.7 vs 20.7 +/- 0.7 mL.kg.min(-1), P = 0.017) as well as a significant decrease in resting systolic (152 +/- 2 vs 145 +/- 2 mm Hg, P = 0.037) and mean arterial (109 +/- 1 vs 105 +/- 1 mm Hg, P = 0.021) BP. No significant (P < 0.05) effects were seen of aerobic exercise training on RPF (208.8 +/- 12.2 vs 197.1 +/- 13.1 mL.min(-1).1.73 m(-2)), GFR (68.9 +/- 3.6 vs 69.0 +/- 3.9 mL.min(-1).1.73 m(-2)), or filtration fraction (35.3 +/- 2.3 vs 37.1 +/- 2.4%) on the low Na+ diet or RPF (210.6 +/- 12.8 vs 212.1 +/- 11.7 mL.min(-1).1.73 m(-2)), GFR (72.9 +/- 4.1 vs 77.3 +/- 4.3 mL.min(-1).1.73 m(-2)), or filtration fraction (37.1 +/- 2.5 vs 37.7 +/- 3.0%) on the high Na+ diet.

CONCLUSIONS

Our results suggest that changes in renal hemodynamics do not contribute to the reduction in resting BP in older hypertensive persons.

Pharmacogenomics and cardiovascular drugs: need for integrated biological system with phenotypes and proteomic markers

Personalized medicine is based on a better knowledge of biological variability, considering the important part due to genetics. When trying to identify involved genes and their products in differential cardiovascular drug responses, a five-step strategy is to be followed: 1) Pharmacokinetic-related genes and phenotypes (2) Pharmacodynamic targets, genes and products (3) Cardiovascular diseases and risks depending on specific or large metabolic cycles (4) Physiological variations of previously identified genes and proteins (5) Environment influences on them. After summarizing the most well-known genes involved in drug metabolism, we will take as example of drugs, the statins, considered as very important drugs from a Public-Health standpoint, but also for economical reasons. These drugs respond differently in human depending on multiple polymorphisms. We will give examples with common ApoE polymorphisms influencing the hypolipemic effects of statins. These drugs also have pleiotropic effects and decrease inflammatory markers. This illustrates the need to separate clinical diseases phenotypes in specific metabolic pathways, which could propose other classifications, of diseases and related genes. Hypertension is also a good example of clinical phenotype which should be followed after various therapeutic approaches by genes polymorphisms and proteins markers. Gene products are under clear environmental expression variations such as age, body mass index and obesity, alcohol, tobacco and dietary interventions which are the first therapeutical actions taken in cardiovascular diseases. But at each of the five steps, within a pharmacoproteomic strategy, we also need to use available information from peptides, proteins and metabolites, which usually are the gene products. A profiling approach, i.e., dealing with genomics, but now also with proteomics, is to be used. In conclusion, the profiling, as well as the large amount of data, will more than before render necessary an organized interpretation of DNA, RNA as well as proteins variations, both at individual and population level.

Arterial stiffness and the renin-angiotensin-aldosterone system

Arterial stiffness has recently been recognised as an independent risk factor for cardiovascular morbidity and mortality in hypertension. Many of the complications seen with angiotensin II (Ang II) excess or hyperaldosteronism--an increased event rate, left ventricular hypertrophy, endothelial dysfunction and target organ damage--are also associated with arterial stiffness. It is possible that reduced arterial compliance may be one mechanism whereby increased activity of the renin-angiotensin-aldosterone system (RAAS) produces adverse vascular effects. Common pathophysiological processes, altered collagen turnover and increased fibrosis may underlie both arterial stiffness and RAAS-associated vascular damage. While it is recognised that patients with hyperaldosteronism have increased arterial stiffness, the role of the RAAS in modulating arterial compliance in essential hypertension and in normotensive subjects is less clear cut. There is, however, more consistent data which show that drugs that interfere with Ang II or aldosterone, namely angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs) and aldosterone antagonists, all reduce arterial stiffness. In many cases, this is to a greater extent than predicted from the extent of reduction in blood pressure (BP), suggesting a role for RAAS in vascular stiffness in hypertensive subjects. There is also evidence that combined ACE inhibitors (ACE-Is) and ARBs may have an additive effect in reducing stiffness. The reduction in cardiovascular mortality in end-stage renal disease patients treated with ACE-Is was preferentially seen in those who had reduced arterial stiffness. These data suggest that, in addition to regulation of vascular biology and BP, the RAAS is an important determinant of arterial stiffness in health and, more particularly, in disease.

Is aldosterone the missing link in refractory hypertension?: aldosterone-to-renin ratio as a marker of inappropriate aldosterone activity

Use of the random aldosterone-to-renin ratio (ARR) as a reliable marker of inappropriate aldosterone activity has led to primary aldosteronism (PA) being increasingly diagnosed in hypertensive patients. At least 10% of hypertensives have been found to have PA, the majority of whom presumably have bilateral adrenal hyperplasia or idiopathic hyperaldosteronism as an aetiology for PA. Whilst these patients clearly have excess aldosterone activity, they have in common many features that are found in hypertensive patients in general, amongst which include heightened angiotensin II adrenal sensitivity. Whether these individuals belong within the spectrum of 'essential hypertension' is being debated, but is probably irrelevant clinically since they appear to respond favourably to spironolactone treatment. In addition, there is recent evidence suggesting that these patients overexpress a key enzyme involved in aldosterone production, the aldosterone synthase, the activity of which appears to relate to its genotypic variation.

The neurohormonal natural history of essential hypertension: towards primary or tertiary aldosteronism?

Use of the aldosterone-to-renin ratio has controversially suggested that approximately 10% of hypertensives have primary aldosteronism, and most of these individuals are thought to have idiopathic hyperaldosteronism. The usual renin-angiotensin system control is intact in these individuals and is similar to that in low renin and essential hypertensives, differing only in the degree of sensitivity. There is recent evidence suggesting that hyperaldosteronism relates to aldosterone synthase genetic polymorphism, and also that increased angiotensin II stimulation of the adrenal glands appears to paradoxically upregulate the receptors increasing angiotensin II sensitivity. Taken together, the possibility arises that, in susceptible hypertensives, hyperaldosteronism could be acquired. Indeed, it is well known that renin-driven renovascular hypertension is associated with the development of hyperaldosteronism. Hypothetically, within the wider hypertensive population, these findings set the scene that angiotensin II adrenal sensitivity increases over time until the secretion of aldosterone becomes "autonomous" and hence "tertiary" aldosteronism in a significant proportion of hypertensives.