Opposite effects of losartan and atenolol on natriuretic peptides in patients with hypertension and left ventricular hypertrophy: a LIFE substudy

Do Losartan and Atenolol have Differential Effects on BNP and Central Haemodynamic Parameters?

Introduction. It has been suggested that angiotensin-converting enzyme inhibitors (ACE-Is) and angiotensin II receptor blockers (ARBs) have a differential effect on brachial and aortic haemodynamics. This is why they seem to have beneficial effects that are beyond brachial blood pressure (BP) lowering. We aimed to investigate if this was the case with losartan when compared to atenolol. We also investigated the differential effect of losartan and atenolol on the prognostic marker, brain type natriuretic peptide (BNP).

Methods. We studied 17 patients who were similar to those in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study. Patients were randomised to receive four months of losartan and atenolol in a crossover fashion. Main outcome measures were BNP and Augmentation index (AIx), which gives an indication of central haemodynamics. Brachial pulse wave velocity (PWV) and time to reflected wave (Tr) were measured as an indication of vascular stiffness.

Results. BNP was significantly lower on losartan than atenolol (p=0.007). AIx was lower on losartan than atenolol (p=0.03), however, this result was not significant when heart rate was considered as a covariate (p=0.09). Heart rate was significantly lower on atenolol than losartan (p=0.03). There was no difference between treatments for both brachial PWV and Tr (p=0.2 and p=0.99, respectively).

Conclusion. The benefits seen when losartan was compared to atenolol in the LIFE trial may be due to a reduction in BNP. We failed to detect a differential effect in central compared to peripheral haemodynamics when losartan was compared to atenolol.

Time course and mechanisms of the anti-hypertensive and renal effects of liraglutide treatment

AIMS

Glucagon-like peptide-1 receptor agonist studies have revealed clinically significant reductions in systolic blood pressure (SBP). The aim was to investigate the time course of the anti-hypertensive effect of liraglutide treatment and potential underlying mechanisms.

METHODS

We used an open-label, single-centre trial; 31 participants with Type 2 diabetes and hypertension completed the study. All participants were treated with liraglutide escalated to a maximum dose of 1.8 mg/day for 7 weeks, followed by a 21-day washout period. The primary outcome was a change in 24-h SBP.

RESULTS

Twenty-four-h SBP increased by 10 mmHg on day 3 (P = 0.008) and 7 mmHg on day 7 (P = 0.033, 0.6 mg/day). On day 29, (1.8 mg/day), 24-h SBP was 7 mmHg lower compared with baseline (P = 0.11). Following the treatment period (day 49) and after washout (day 70), 24-h BP was equivalent to baseline. In addition, extracellular volume (ECV) was reduced by 2.0 l [95% confidence interval (CI) = 1.0-3.1 l, P < 0.001] and midregional-pro-atrial natriuretic peptide (MR-proANP) was reduced by 20% (95% CI = 12-28%, P < 0.001). Also, urinary albumin excretion declined by 30% (95% CI = 12-44%, P = 0.003), GFR by 11 ml/min/1.73 m(2) (95% CI = 7.2-14.4 ml/min/1.73 m(2) , P < 0.001) and fractional albumin excretion by 29% (95% CI = 3-48%, P = 0.032).

CONCLUSIONS

Liraglutide treatment was associated with an initial increase in 24-h SBP, followed by a 7 mmHg reduction after escalation to 1.8 mg/day. This effect subsided after 4 weeks of maximum dose. Reductions in ECV and MR-proANP may explain the anti-hypertensive potential. Liraglutide treatment was associated with reversible reductions in albuminuria and GFR, which has to be confirmed in randomized trials.

The Value of N-Terminal Pro–B-Type Natriuretic Peptide in Determining Antihypertensive Benefit

We investigated 3 hypotheses: (1) N-terminal pro–B-type natriuretic peptide (NT-proBNP) predicts cardiovascular disease events in patients with hypertension, (2) NT-proBNP is associated with blood pressure variability, and (3) NT-proBNP predicts benefit from antihypertensive regimens. The Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT) randomized a subset of 6549 patients at risk with no history of coronary heart disease to either atenolol-based or amlodipine-based blood pressure–lowering treatment. During 5.5 years of follow-up, 485 cardiovascular disease cases accrued and were matched with 1367 controls. Baseline and 6-month in-trial NT-proBNP were measured. The results show that NT-proBNP improves cardiovascular disease risk prediction beyond established predictors, continuous net reclassification improvement of 22.3% ( P <0.0001). Furthermore, a 1-mm Hg increase in the SD of systolic blood pressure was associated with 2% higher baseline NT-proBNP in a multivariable regression analysis ( P <0.0001). However, NT-proBNP predicted cardiovascular disease risk independently of blood pressure variation (odds ratio per SD increase in log NT-proBNP 1.24; 95% confidence interval, 1.06–1.45; P =0.007). Atenolol-based treatment led to a 69.6% increase in NT-proBNP at 6 months ( P <0.0001). In contrast, amlodipine-based treatment reduced NT-proBNP by 36.5% ( P <0.0001). Amlodipine recipients who achieved a 6-month NT-proBNP below the median (61 pg/mL) were at lower risk of cardiovascular disease when compared with those who did not (odds ratio, 0.58; 95% confidence interval, 0.37–0.91) after adjustment for confounders inclusive of baseline NT-proBNP and achieved blood pressure. If confirmed, these novel results suggest that NT-proBNP, as well as aiding cardiovascular disease risk assessment, may also help assess the efficacy of specific antihypertensive regimens. Further relevant studies seem warranted.

Biological, electrical and echocardiographic indices versus cardiac magnetic resonance imaging in diagnosing left ventricular hypertrophy

The aim of this study was to compare the diagnostic performance of N-terminal pro-brain natriuretic peptide (NT-proBNP), electrocardiographic (ECG) criteria and transthoracic echocardiography (TTE) versus cardiac magnetic resonance imaging in detecting left ventricular hypertrophy (LVH). The study included 42 hypertensive subjects with mean±s.d. age 48.1±12.3 years, 57.1% men, 24-h ambulatory blood pressure 144/89 mm Hg, left ventricular ejection fraction >50%, without symptoms of heart failure, and not taking any drugs that interfere with hormonal regulation. The accuracies of the methods in detecting LVH were compared at two diagnostic LVH cutoffs: low, 83 g m(-2) in men and 67 g m(-2) in women; and high, 96 g m(-2) in men and 81 g m(-2) in women. With the low and high LVH cutoffs, the areas under the receiver-operating characteristic curves and the optimal values for NT-proBNP were 0.761, 0.849, 200 and 421 pg ml(-1), respectively. An NT-proBNP level under 30 pg ml(-1) ruled out LVH with 100% sensitivity. The optimal values and literature-based values of NT-proBNP allowed a correct classification of 73-81% of the subjects. In 80-90% of the cases, the diagnostic accuracy of NT-proBNP was close to that of ECG criteria but lower than that of TTE criteria. Interestingly, combining ECG criteria and NT-proBNP level improved the diagnostic performance to be at least comparable to that of TTE: the percentages of correctly classified subjects were 73-95% vs. 67-86%, respectively. Of note, the range considers both diagnostic LVH cutoffs. The simultaneous use of ECG criteria and NT-proBNP plasma levels seemed to be powerful enough to detect LVH in most hypertensive subjects.

Genetic variation in the natriuretic peptide system, circulating natriuretic peptide levels, and blood pressure: an ambulatory blood pressure study

BACKGROUND

In a large collaborative study (n > 50,000), common variants in the natriuretic peptide (NP) genes were found to be associated with circulating NP levels and also with blood pressure (BP) levels based on office BP measurements (OBPMs). It is unknown if determining an individual's BP by 24-h ambulatory BP measurements (ABPMs) will influence the effect of NP gene variations on BP levels.

METHODS

We used rs632793 at the NPPB (NP precursor B) locus to investigate the relationship between genetically determined serum N-terminal pro-brain NP (NT-proBNP) concentrations and BP levels determined by both 24-h ABPMs and OBPMs in a population consisting of 1,397 generally healthy individuals taking no BP-lowering drugs.

RESULTS

rs632793 was significantly correlated with serum Nt-proBNP levels (r = 0.10, P = 0.0003), and participants with the A:A genotype had lower serum Nt-proBNP levels than participants with the G:G genotype (geometric mean (95% confidence interval (CI)): 34.8 (31.5-38.4) pg/ml vs. 48.1 (41.9-55.3) pg/ml, P = 0.0002), but higher 24-h ambulatory BP levels (mean difference (95% CI): 2.0 (0.1-4.1) mm Hg, P = 0.043, for systolic BP and 1.7 (0.4-3.1) mm Hg, P = 0.011, for diastolic BP). Office BP decreased across the genotypes from A:A to G:G, but the differences did not reach statistical significance (P ≥ 0.12).

CONCLUSIONS

This study suggests that 24-h ABPMs is a better method than OBPMs to detect significant differences in BP levels related to genetic variance and provides further evidence that the NP system plays an important role in BP regulation.

Antihypertensive efficacy of the losartan/hydrochlorothiazide combination and its effect on plasma B-type natriuretic peptide in hypertensive patients uncontrolled by angiotensin II type 1 receptor antagonist-based therapy: a multicentre prospective observational study

BACKGROUND AND OBJECTIVES

Although strict blood pressure (BP) control is effective in the prevention of cardiovascular events, it is often insufficient in many hypertensive patients. B-type natriuretic peptide (BNP) has been shown to be associated with cardiovascular events. We investigated the effects of the losartan/hydrochlorothiazide combination on BP and plasma BNP in hypertensive patients uncontrolled by an angiotensin II type 1 receptor antagonist (angiotensin receptor blocker [ARB])-based therapy.

METHODS

In a multicentre prospective observational study, we enrolled 185 patients aged 36-79 years (mean age 63.8 years) with essential hypertension but without symptoms of heart failure who received an ARB-based therapy for ≥3 months but failed to achieve a target BP recommended by the Japanese Society of Hypertension (JSH). ARBs were switched to losartan (LOS) 50 mg/hydrochlorothiazide (HCTZ) 12.5 mg. The antihypertensive efficacy, safety, and effects of this combination on blood biochemical parameters and plasma BNP were evaluated for 12 months.

RESULTS

Mean ± SD systolic and diastolic BP decreased from 152 ± 13/87 ± 10 mmHg to 128 ± 14/74 ± 10 mmHg, respectively, after 12 months (p < 0.001). Mean ± SD plasma BNP levels decreased significantly from 46.0 ± 83.0 pg/mL to 40.8 ± 68.0 pg/mL (p < 0.05). The percentage of patients who achieved the JSH 2004 target BP was 51% after 12 months; the percentage was 63% in elderly patients aged ≥65 years without complications, and 43% in patients with concomitant diabetes mellitus or chronic kidney disease. No association was found between a decrease in plasma BNP levels and BP, age, body mass index or estimated glomerular filtration rate. There was a significant increase in serum uric acid and a decrease in serum potassium, but both were within the range of normal values. Adverse events were observed in 8.6% of the patients.

CONCLUSION

Antihypertensive treatment using two types of drugs (LOS/HCTZ) with different mechanisms yielded potent antihypertensive efficacy with safety and decreased plasma BNP levels.

Variability of NT-proBNP and its relationship with inflammatory status in patients with stable essential hypertension: a 2-year follow-up study

BACKGROUND

The variability of NT-proBNP levels has been studied in heart failure, yet no data exist on these changes over time in hypertensive patients. Furthermore, studies on the relationship between natriuretic peptides and inflammatory status are limited.

METHODOLOGY/PRINCIPAL FINDINGS

220 clinically and functionally asymptomatic stable patients (age 59 ± 13, 120 male) out of 252 patients with essential hypertension were followed up, and NT-proBNP was measured at baseline, 12 and 24 months. No differences in NT-proBNP were found with respect to the basal stage in the hypertrophic group, but significant changes were found in non-hypertrophic subjects. The reproducibility of NT-proBNP measurements was better in patients with hypertrophy than in the non-hypertrophic group for the three intervals (stage I-basal; stage II-stage I; stage II-basal) with a reference change value of 34%, 35% and 41%, respectively, in the hypertrophic group. A more elevated coefficient of correlation was obtained in the hypertrophic group than in patients without hypertrophy: basal versus stage I (r = 0.79, p < 0.0001 and r = 0.59, p < 0.0001) and stage I versus stage II (r = 0.86, p < 0.0001 and r = 0.56, p < 0.0001). Finally, levels of NT-proBNP significantly correlated with sTNF-R1 (p < 0.0001) and IL-6 (p < 0.01) during follow-up. A multivariate linear regression analysis showed that sTNF-R1 is an independent factor of NT-proBNP.

CONCLUSIONS/SIGNIFICANCE

This work shows that there is good stability in NT-proBNP levels in a follow-up study of asymptomatic patients with stable hypertension and left ventricular hypertrophy. As a consequence, assessment of NT-proBNP concentrations may be a useful tool for monitoring the follow-up of hypertensive patients with hypertrophy. Measured variations in peptide levels, exceeding 35% in a 12-month follow-up and 41% in a 24-month follow-up, may indicate an increase in cardiovascular risk, and therefore implies adjustment in the medical treatment. In addition, this study shows a link between neurohormonal and inflammatory activation in these patients.

Natriuretic peptides: ready for prime-time in hypertension?

Over the past years, natriuretic peptides have been recognised not only as important contributors to cardiovascular regulation but also as valuable markers in overt cardiac disease, including heart failure or coronary disease. More recently, these markers have shown their ability to detect preclinical cardiac alterations in different settings. In this respect, natriuretic peptides offer a new perspective for risk stratification in hypertension. They are correlated to various features of cardiac remodelling provoked by hypertension. They also depend on vascular properties, including blood pressure level and aortic stiffness. In addition to being integrative markers of cardiovascular alterations, several studies have shown their value in predicting all-cause mortality or cardiovascular mortality and morbidity in the general population. At least three consistent studies are now available in hypertension also showing this prognostic value. This performance, together with the ease of measurement, low cost and widespread availability, should prompt the wide use of natriuretic peptides for risk stratification in hypertension, at least in patients with normal electrocardiography, but also in most hypertensive patients.

Fifteen years of losartan: what have we learned about losartan that can benefit chronic kidney disease patients?

Losartan, the first AT1 receptor blocker (ARB), was FDA approved 15 years ago. During those years, researchers and clinicians have developed a growing base of knowledge on the benefits of losartan, particularly for hypertension and renal disease. These benefits include decreasing proteinuria, slowing the progression of diabetic nephropathy, controlling hypertension, and decreasing stroke risk in patients with left ventricular hypertrophy. Although many of the benefits of losartan represent a class effect for ARBs, losartan has pharmacokinetic and pharmacodynamic characteristics and effects that are unique and are not a class effect. For example, a shorter duration of action is seen with this first ARB compared with other more recently approved ARBs. Losartan also has a uricosuric effect not seen in other ARBs and attenuates platelet aggregation, which is not seen or is seen to a lesser extent with the other ARBs. This review presents the physiological effects of losartan on the kidney and discusses relevant clinical outcomes.

Managing hypertension in cardiology practice according to risk profile

Cardiologists play a central role in managing hypertensive patients, although recent surveys reveal a marked discrepancy between cardiologists' appreciation of their patients' risk status and the measures taken to reduce that risk. The diagnosis and the management of hypertension, in fact, must be viewed today not in isolation, but as part of a patients' global cardiovascular (CV) risk, resulting from the concomitant presence of a variety of risk factors, organ damage (left ventricular hypertrophy, carotid or peripheral atherosclerosis, microalbuminuria or impaired glomerular filtration rate), and hypertension-related clinical conditions. The choice of timing and the intensity of antihypertensive treatment should be based on blood pressure (BP)-lowering efficacy and the propensity to favourably impact patient's individual absolute CV disease risk profile. As part of this paradigm shift in CV disease prevention strategy, cardiologists can take several key steps to help improve standards of hypertension control: (i) increase the awareness of total risk management; (ii) initiate an integrated management strategy tailored to the individual patient's global CV risk (e.g. hypertension, hypercholesterolaemia, diabetes, age, smoking and gender); (iii) use any elevation in BP as a gateway to begin total risk management and (iv) utilise combination therapies (particularly fixed-dose combinations) to achieve more rapid and persistent BP control and improve patient compliance/persistence with therapy. To help improve standards of hypertension control in the cardiology setting, this review examines the concept of treating hypertension using a global risk assessment approach and proposes effective hypertensive therapy as part of global risk management in patients typically seen in cardiology practice.

B-type natriuretic peptide, a marker of asymptomatic left ventricular dysfunction in type 2 diabetic patients

AIM

To evaluate BNP in assessing LV functions in asymptomatic type 2 diabetic patients.

METHODS

BNP was measured in 91 consecutive patients with type 2 diabetes mellitus. According to Doppler echocardiography, patients were first separated into three categories: normal LV function, or isolated diastolic or systolic LV dysfunction. As some patients with diastolic dysfunction were treated for hypertension, the population was divided into four groups: groups 1, 2 and 3 all had no antihypertensive treatment, and had normal LV function, and isolated diastolic and systolic LV dysfunction, respectively; and group 4 were being treated with antihypertensive drugs and had diastolic LV dysfunction.

RESULTS

In group 1, BNP levels (13+/-2 ng/L) were lower than in group 2 (87+/-20 ng/L, P<0.0001) or group 3 (213+/-32 ng/L, P<0.0001), but were similar to those of group 4 (32+/-6 ng/L, P=0.14). ROC analysis revealed a rule-out value of 23 ng/L for group 1 versus group 2, and of 239 ng/L for group 2 versus group 3. In groups 1, 2 and 3 taken together, BNP levels were correlated with urinary albumin excretion rate (r=0.80, P<0.0001) and pulse pressure (r=0.65, P<0.0001). In group 4, patients receiving ACE inhibitors had lower BNP levels than those receiving ss-blockers.

CONCLUSION

BNP can be used to pre-screen asymptomatic type 2 diabetic patients with LV dysfunction, and may reveal vascular remodelling in type 2 diabetes mellitus.

Obese and nonobese patients with essential hypertension show similar N-terminal proBNP plasma levels

BACKGROUND

Multiple studies have focused on the influence of obesity on natriuretic peptide levels. However, the effect of obesity on amino-terminal propeptide of B-type natriuretic peptide (NT-proBNP) levels in hypertensive (HT) patients remains uncertain.

METHODS

We studied 252 asymptomatic patients (60 +/- 13 years, 136 men) with essential HT. A routine physical examination, anthropometry, laboratory analyses, echo-Doppler study, and NT-proBNP level determination were performed.

RESULTS

NT-proBNP levels were similar in both obese and nonobese HT (median 56 (25-130) pg/ml vs. median 51 (26-129) pg/ml, P = 0.488). No significant differences were found in obese or nonobese patients with left ventricular hypertrophy (LVH) (median 135 (73-425) pg/ml vs. median 151 (64-274) pg/ml, P = 0.597). The area under the curve was 0.89 +/- 0.03 for NT-proBNP to diagnose LVH in the obese HT patients and 0.88 +/- 0.03 in the nonobese. A logistic regression analysis showed that age, gender, and left ventricular mass index (LVMI) were independent predictors of NT-proBNP levels. Body mass index (BMI) was not significantly associated with NT-proBNP in LVH HT patients.

CONCLUSIONS

Obesity is not statistically associated with NT-proBNP levels in HT asymptomatic patients. The same results were observed in our group of patients with LVH. These data are in contrast with those previously found in heart failure, and raise questions about the role of obesity per se as primary cause of decreased NT-proBNP levels in other pathophysiological conditions.

Angiotensin II: a hormone involved in and contributing to pro-hypertrophic cardiac networks and target of anti-hypertrophic cross-talks

Angiotensin II (Ang II) plays a major role in the progression of myocardial hypertrophy to heart failure. Inhibiting the angiotensin converting enzyme (ACE) or blockade of the corresponding Ang II receptors is used extensively in clinical practice, but there is scope for refinement of this mode of therapy. This review summarizes the current understanding of the direct effects of Ang II on cardiomyocytes and then focus particularly on interaction of components of the renin-angiotensin system with other hormones and cytokines. New findings described in approximately 400 papers identified in the PubMed database and published during the 2.5 years are discussed in the context of previous relevant literature. The cardiac action of Ang II is influenced by the activity of different isoforms of ACE leading to different amounts of Ang II by comparison with other angiotensinogen-derived peptides. The effect of Ang II is mediated by at least two different AT receptors that are differentially expressed in cardiomyocytes from neonatal, adult and failing hearts. The intracellular effects of Ang II are influenced by nitric oxide (NO)/cGMP-dependent cross talk and are mediated by the release of autocrine factors, such as transforming growth factor (TGF)-beta1 and interleukin (IL)-6. Besides interactions with cytokines, Ang II is involved in systemic networks including aldosterone, parathyroid hormone and adrenomedullin, which have their own effects on cardiomyocytes that modify, amplify or antagonize the primary effect of Ang II. Finally, hyperinsulemia and hyperglycaemia influence Ang II-dependent processes in diabetes and its cardiac sequelae.

Does NT-proBNP remain a sensitive biomarker for chronic heart failure after administration of a beta-blocker?

BACKGROUND

Beta-blockers exert complex effects on plasma N-terminal-pro-B-type natriuretic peptide (NT-proBNP) level.

HYPOTHESIS

We aimed to investigate whether NT-proBNP was still able to mirror the severity of chronic heart failure and predict the prognosis of the disease after administration of a beta-blocker.

METHODS

Forty-four patients with chronic congestive heart failure were enrolled in the study to randomly receive carvedilol or bisoprolol in addition to background therapy. These patients underwent clinical measurement and blood sampling for NT-proBNP measurement at baseline and 3 or 7 months after the addition of the beta-blocker. The patients were followed-up for 3 years in order to register the occurrence of all-cause death.

RESULTS

NT-proBNP level showed a positive correlation with the severity of heart failure as evaluated by New York Heart Association (NYHA) classification both before and after administration of either beta-blocker. The relationship between NT-proBNP and NYHA class was not weakened with the duration of therapy. Furthermore, NT-proBNP was the only independent predictor of all-cause mortality both before and after administration of either beta-blocker. Left ventricular ejection fraction (LVEF), left ventricular end diastolic diameter (LVEDD), age, NYHA class and treatment group were not independently predictive of mortality in this study.

CONCLUSIONS

The ability of NT-proBNP to reflect the severity and to predict the endpoint in chronic heart failure is not undermined after administration of a beta-blocker, suggesting that NT-proBNP remains a sensitive biomarker for chronic heart failure both before and after administration of a beta-blocker.

The effect of angiotensin receptor blockers for preventing atrial fibrillation

Atrial fibrillation is the most common sustained cardiac arrhythmia in clinical practice, and causes significant burden to patients and health care systems. Clinicians treat existing atrial fibrillation with anticoagulation and/or drugs that utilize either a rate or rhythm control strategy. It remains unclear how best to reduce cardiovascular morbidity and mortality in this population. Prevention of atrial fibrillation using angiotensin receptor blockers, which affect ion currents and refractoriness in atrial myocytes, regress or prevent atrial fibrosis, decrease left atrial size, regress left ventricular hypertrophy, modulate sympathetic nerve activity, reduce inflammation, and reduce blood pressure, may become an important and desirable alternative.

Brain natriuretic peptide: clinical and research challenges

Natriuretic peptides, in particular, brain or B-type, are useful for the assessment of patients presenting with dyspnea to the medical office or emergency department. Levels of natriuretic peptides are useful for assessing prognosis of heart failure or coronary syndrome patients. Less is known about serial peptide measurements for guiding treatment strategies in heart failure. The authors review the uses, pitfalls, and practical points for using natriuretic peptides clinically.

Role of Angiotensin II in the Evolution of Diastolic Heart Failure

More than half of all persons with heart failure (HF) have diastolic HF. The prevalence of diastolic HF increases from 46% in persons younger than 45 years to 59% in those 85 years and older. The annual mortality rate associated with diastolic HF is >10%. Diagnosis is based on signs and symptoms of HF, elevated plasma B-type natriuretic peptide, preserved left ventricular systolic function, and evidence of diastolic dysfunction by Doppler examination on two-dimensional echocardiography. Approximately 80% of patients with diastolic HF have increased left ventricular mass and a history of hypertension. Neurohormonal activation is a key aspect of this condition. Studies suggest that activation of the renin-angiotensin-aldosterone system, specifically direct cardiac effects of angiotensin II and aldosterone, contributes to the pathogenesis and progression of diastolic dysfunction. Hence, there is a rationale for use of agents that antagonize the renin-angiotensin-aldosterone system, such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and aldosterone antagonists, in patients with heart failure.

Perindopril-based blood pressure-lowering therapy reduces amino-terminal-pro-B-type natriuretic peptide in individuals with cerebrovascular disease

OBJECTIVE

The plasma amino-terminal-pro-B-type natriuretic peptide (NT-proBNP) level predicted congestive heart failure, myocardial infarction, and ischaemic stroke in participants of the Perindopril Protection Against Recurrent Stroke Study (PROGRESS), a placebo-controlled study of the effects of blood pressure lowering on cardiovascular events among individuals with cerebrovascular disease. Active treatment comprised a flexible regimen based on perindopril, with the addition of indapamide at the discretion of treating physicians. Active treatment reduced cardiovascular events, and we therefore investigated whether active treatment modified NT-proBNP and other cardiovascular risk factors.

METHODS

We measured NT-proBNP and other cardiovascular risk factors at randomization and after 13 months of therapy in a subset of 357 PROGRESS participants.

RESULTS

Baseline systolic and pulse pressures were higher in individuals with elevated baseline NT-proBNP levels. In comparison with placebo, active treatment reduced the blood pressure and NT-proBNP levels, and increased renin levels. Reduction of NT-proBNP levels by active treatment was most evident in individuals with baseline NT-proBNP levels in the highest quarter (> 26 pmol/l), with a median reduction of 16 pmol/l (interquartile range 0-51 pmol/l, P = 0.004), corresponding to a median decrease of 39% (interquartile range 0-69%). Active treatment reduced blood pressure similarly for individuals in each of the four quarters of baseline NT-proBNP. Active therapy had no effect on plasma lipid, C-reactive protein, homocysteine, or soluble vascular cell adhesion molecule 1 levels.

CONCLUSION

We conclude that plasma NT-proBNP level, in addition to predicting cardiovascular risk, may provide a measure of risk reduction by blood pressure-lowering therapy.

Potential mechanisms of stroke benefit favoring losartan in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study

INTRODUCTION

The Losartan Intervention For Endpoint reduction in hypertension (LIFE) study is the first, and, so far, the only endpoint trial in patients with hypertension and left ventricular hypertrophy (LVH) to show a divergent therapeutic outcome of one treatment modality over another with equivalent blood pressure control. The purpose of this article is to review post hoc sub-analyses of LIFE study data and other clinical studies that offer some insight into possible treatment-related differences contributing to the superior stroke outcome of losartan versus atenolol beyond blood pressure reduction.

METHODS

Relevant randomized clinical trials and review articles were identified through a MEDLINE search of English-language articles published between 1990 and 2006 using the search terms losartan, atenolol, LIFE, hypertension, and LVH. Articles describing major clinical studies, new data, or mechanisms pertinent to the LIFE study were selected for review.

RESULTS

Differences in blood pressure or in the distribution of add-on medications were not evident between study groups in the LIFE study. Thus, the observed outcomes benefits favoring losartan may involve other possible mechanisms, including differential effects of losartan and atenolol on LVH regression, left atrial diameter, atrial fibrillation, brain natriuretic peptide, vascular structure, thrombus formation/platelet aggregation, serum uric acid, albuminuria, new-onset diabetes, and lipid metabolism. Alternative explanations for the LIFE study findings have also been put forward, including the choice of atenolol as an appropriate active comparator and differential effects between treatment groups on central pulse pressure. Additional clinical trials are needed to determine if the beneficial effects of losartan seen in LIFE are shared by other inhibitors of the renin-angiotensin system.

CONCLUSION

Sub-analyses of the LIFE study data suggest that losartan's stroke benefit may arise from a mosaic of mechanisms rather than a single action. Further studies are expected to continue to delineate the mechanisms of differential responses to treatments in LIFE.

The effects of medications on circulating levels of cardiac natriuretic peptides

Circulating cardiac natriuretic peptide levels are being used increasingly in a range of clinical circumstances. Since it is evident that drugs used in the treatment of cardiovascular disorders can modulate natriuretic peptide levels, we here review the literature documenting these effects. Diuretics, blockers of the renin-angiotensin system, vasodilator agents, dopamine-like agonists, amiodarone, and perhaps allopurinol and statins suppress natriuretic peptide levels, most obviously in heart failure. Beta-blockers stimulate natriuretic peptide concentrations in hypertensive subjects, whereas in heart failure they have little effect or are stimulatory in the short term and inhibitory with sustained therapy. Digitalis compounds and aspirin tend to increase natriuretic peptide levels, and calcium channel blocking agents have varying effects depending on the individual drug and duration of administration. The effects of other drugs are less clear. Additional information is needed regarding the effects of medications along with dissection of the role of altered cardiac secretion versus changes in plasma clearance as explanation for drug-induced perturbations in natriuretic peptide concentrations. In the meantime, clinicians need to consider the known effects of medications when interpreting plasma levels of the cardiac natriuretic peptides.

What is the role of angiotensin-receptor blockade in cardiovascular protection?

The role of angiotensin II, the key mediator of the renin-angiotensin-aldosterone system, in the pathophysiology of cardiovascular disease is well known. Pharmacologic interruption of the activity of angiotensin II, either through blockade of the angiotensin receptor or inhibition of angiotensin-converting enzyme, is associated with a reduction in cardiovascular disease morbidity and mortality, as evidenced by accumulated data from large-scale, well-controlled clinical trials in high-risk populations. As the underlying mechanisms of vascular disease and the effects of blockade of the renin-angiotensin-aldosterone system on these processes have been further defined, the therapeutic focus has begun to shift toward prevention of disease progression at earlier stages. Continued research has identified early signs of vascular disease, such as endothelial dysfunction and vascular and cardiac remodeling, which occur long before clinical manifestations of cardiovascular disease become evident. Diagnostic tests are now available to assess otherwise healthy individuals for these signs. A preliminary trial is under way to evaluate the role of angiotensin receptor blockade as preventive treatment of individuals with early signs of vascular or cardiac disease.

Losartan

Losartan (Cozaar) is an angiotensin AT1 receptor antagonist. It is approved in numerous countries for the treatment of hypertension and has been approved in the UK, the US and several European countries for stroke risk reduction in patients with hypertension and left ventricular hypertrophy (LVH). Losartan is recommended for use alone or with hydrochlorothiazide, but it can also be administered with other antihypertensive medications. In patients with hypertension, losartan effectively lowers blood pressure and also leads to regression of LVH. In the large, well designed LIFE (Losartan Intervention For Endpoint reduction in hypertension) study in patients with hypertension and LVH, losartan was more effective than atenolol in reducing the composite primary endpoint of cardiovascular (CV) mortality, stroke or myocardial infarction (MI). This was mainly due to a significant 25% reduction in the risk of stroke in the losartan group. Losartan recipients also had a significantly lower incidence of new-onset diabetes mellitus compared with atenolol recipients. Similar benefits were observed in several patient subgroups from the LIFE study, but not in the subgroup of Black patients. Losartan is well tolerated and is a cost effective alternative to atenolol in the setting of stroke reduction. Comparative data on clinical outcomes in hypertensive patients for losartan versus other antihypertensive agents would be of interest. Nonetheless, in addition to its established antihypertensive and end organ effects, the LIFE study indicates that, with the possible exception of Black patients, losartan can reduce the risk of stroke in patients with hypertension and LVH.