Implications of recently published trials of blood pressure-lowering drugs in hypertensive or high-risk patients

Left Ventricular Hypertrophy Regression During Antihypertensive Treatment in an Outpatient Clinic (the Campania Salute Network)

Background

Regression of left ventricular (LV) hypertrophy (LVH) has been a goal in clinical trials. This study tests the external validity of results of clinical trials on LVH regression using a large registry from a tertiary care center, to identify phenotypes less likely to achieve regression of LVH.

Methods and Results

Patients from the Campania Salute Network, free of prevalent cardiovascular disease, but with echocardiographic LVH (defined as LV mass index [LVMi] >47 g/m^2.7 in women and >50 g/m^2.7 in men) were included. During a median follow‐up of 67 months, clear‐cut regression of LVH was documented in 14% of patients (13±8% reduction of initial LVMi) or 23% when also considering those with a reduction of LVMi ≥5 g/m^2.7. Patients with persistent LVH were older with longer duration of hypertension, suboptimal blood pressure (BP) control, larger body mass index, LV mass, and carotid intima‐media thickness and included more women and subjects with diabetes mellitus, isolated systolic hypertension, and metabolic syndrome (all P<0.05). Number and class of antihypertensive drugs during follow‐up did not differ between groups. In multiple logistic regression analysis, older age, female sex, obesity, higher baseline LVMi and carotid intima‐media thickness, and suboptimal BP control were significant covariates of persistent LVH (all P≤0.01), independent of diabetes, duration of hypertension, isolated systolic hypertension, follow‐up time and number and class of antihypertensive drugs.

Conclusions

Early initiation of antihypertensive treatment, aggressive BP control, and attention to metabolic aspects are critical to avoid irreversible LVH.

Azilsartan medoxomil in the management of hypertension: an evidence-based review of its place in therapy

Background

Azilsartan (AZI) is a relatively new angiotensin receptor blocker available for the treatment of any stage of hypertension, which was eventually given in combination with chlorthalidone (CLT).

Objective

To review pharmacology and clinical role of AZI monotherapy and AZI/CLT or AZI/amlodipine combination therapies for hypertension management.

Methods

PubMed, Embase, and Cochrane Library were searched using search terms “ azilsartan”, “chlorthalidone,” “pharmacology,” “pharmacokinetics,” “pharmacodynamics,” “pharmacoeconomics,” and “cost-effectiveness.” To obtain other relevant information, US Food and Drug Association as well as manufacturer prescribing information were also reviewed.

Results

Randomized controlled trials demonstrated AZI to be superior to other sartans, such as valsartan, olmesartan, and candesartan, in terms of 24-hour ambulatory blood pressure monitoring (ABPM) reduction with respect. That beneficial effect of azilsartan was also associated with similar safety profiles. When compared to other antihypertensive drugs, azilsartan was found to be superior to any angiotensin-converting enzyme inhibitor, including ramipril, in terms of ABPM results, and noninferior to amlodipine in terms of sleep-BP control. The association of AZI and CLT was then found to be superior to other sartans + thiazide combination therapies in terms of both BP lowering and goal achievement. The combination of AZI and amlodipine has also been tested in clinical trials, but compared only with placebo, demonstrating its superiority in terms of efficacy and similarity in terms of safety.

Conclusion

Azilsartan is a safe and effective treatment option for every stage of hypertension, both alone or in fixed-dose combination tablets with chlorthalidone or amlodipine. Beneficial effects of AZI were also noted in patients with any degree of renal impairment. In addition, safety profiles of AZI were similar to that of the placebo.

Prehypertension: Underlying pathology and therapeutic options

Prehypertension (PHTN) is a global major health risk that subjects individuals to double the risk of cardiovascular disease (CVD) independent of progression to overt hypertension. Its prevalence rate varies considerably from country to country ranging between 21.9% and 52%. Many hypotheses are proposed to explain the underlying pathophysiology of PHTN. The most notable of these implicate the renin-angiotensin system (RAS) and vascular endothelium. However, other processes that involve reactive oxygen species, the inflammatory cytokines, prostglandins and C-reactive protein as well as the autonomic and central nervous systems are also suggested. Drugs affecting RAS have been shown to produce beneficial effects in prehypertensives though such was not unequivocal. On the other hand, drugs such as β-adrenoceptor blocking agents were not shown to be useful. Leading clinical guidelines suggest using dietary and lifestyle modifications as a first line interventional strategy to curb the progress of PHTN; however, other clinically respected views call for using drugs. This review provides an overview of the potential pathophysiological processes associated with PHTN, abridges current intervention strategies and suggests investigating the value of using the "Polypill" in prehypertensive subjects to ascertain its potential in delaying (or preventing) CVD associated with raised blood pressure in the presence of other risk factors.

Renin-angiotensin system blocking drugs

The two major classes of drugs that target the RAS are the angiotensin-converting enzyme (ACE) inhibitors and the selective AT1 receptor blockers (ARBs). Although both of these drug classes target angiotensin II, the differences in their mechanisms of action have implications for their effects on other pathways and receptors that may have therapeutic implications. Both ACEIs and ARBs are effective antihypertensive agents that have been shown to reduce the risk of cardiovascular and renal events. Direct inhibition of renin -the most proximal aspect of the RAS -became clinically feasible from 2007 with the introduction of aliskiren. This latter drug has been shown to be efficacious for the management of hypertension. Combined therapy of direct renin-inhibitors with ACEIs or ARBs has been tested in some clinical situations as congestive HF and proteinuria with diverse results. This article tries to offer an updated review of current knowledge on the use of RAS blocking drugs in clinical settings.

Guidelines on guidelines: focus on isolated systolic hypertension in youth

Current guidelines on isolated systolic hypertension (ISH) suggest the same treatment to patients of all ages. Application of these guidelines in youth with ISH may not be appropriate, as presently no data show adverse outcome or benefit of drug therapy in this group. Simple noninvasive tonometric techniques now enable physicians to measure the central aortic pressure waveform and amplification of the pressure pulse. ISH in youth is usually caused by high amplification of the central pressure wave, whereas ISH in the elderly (>age 60) is attributable to aortic stiffening. This is the only group with ISH shown to have an adverse prognosis and to warrant drug therapy.

Treatment of prehypertension: lifestyle and/or medication

Prehypertension is a warning to individuals with resting blood pressures between 120/80 mmHg and 139/89 mmHg of an insidious progression of blood pressure towards hypertensive levels (≥ 140/90 mmHg). Prehypertension is associated with increased cardiovascular risk and end organ damage compared with individuals who are normotensive. This review primarily focuses on internal and external factors associated with the prevalence of prehypertension. Elucidating all of the factors associated with a rise in resting blood pressure and comparing the effects of medication versus lifestyle changes may aid the clinician in developing a preventive and/or treatment strategy for each individual.

Arterial aging: a review of the pathophysiology and potential for pharmacological intervention

This review begins with a perspective on the effects of arterial aging on society and world events over the past century. Until recently, the use of just one technique to measure blood pressure non-invasively limited progress in understanding the mechanisms involved and the potential of antihypertensive drug therapies. New methods for extracting information from the arterial waveform have followed the (re)introduction of arterial tonometry into clinical practice, together with mathematical analysis in the frequency and time domains. These new methods have exposed the phenomenon of aortic stiffening with age, and early wave reflection arising therefrom, and identified it as the major cause of cardiovascular degeneration. Such findings point to arterial aging as a logical target for the treatment and prevention not only of cardiac, aortic and large artery disease, but also of damage to microvessels in the brain and kidney, which in turn leads insidiously to dementia and renal failure, respectively.

Differential pharmacology and benefit/risk of azilsartan compared to other sartans

Azilsartan, an angiotensin II type 1 (AT₁) receptor blocker (ARB), was recently approved by regulatory authorities for treatment of hypertension and is the 8th ARB to join the clinical market. This article discusses the medical reasons for introducing a new AT₁ receptor blocker and reviews the experimental and clinical studies that have compared the functional properties of azilsartan to those of other ARBs. The main question addressed is: Does azilsartan have distinguishing features that should motivate choosing it over any of the other sartans for use in clinical practice? Based on studies conducted to date in hypertensive patients without serious comorbidities, azilsartan appears to be characterized by a superior ability to control 24-hour systolic blood pressure (BP) relative to other widely used ARBs including valsartan, olmesartan, and candesartan, and presumably others as well (eg, losartan). Compared to these other ARBs, azilsartan may increase the BP target control and response rate by an absolute value of 8%–10%. Greater antihypertensive effects of azilsartan might be due in part to its unusually potent and persistent ability to inhibit binding of angiotensin II to AT₁ receptors. Preclinical studies have indicated that azilsartan may also have potentially beneficial effects on cellular mechanisms of cardiometabolic disease and insulin sensitizing activity that could involve more than just blockade of AT₁ receptors and/or reduction in BP. However, the clinical relevance of these additional actions is unknown. Given that the general ability of antihypertensive drugs to protect against target organ damage is largely mediated by their ability to decrease BP, the enhanced antihypertensive effects of azilsartan should serve to justify clinical interest in this ARB relative to other molecules in the class that have a lower capacity to reduce BP.

Antihypertensive therapy versus alternative therapeutic options for prehypertension: an evidence-based approach

The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC–7) defines hypertension as systolic blood pressure (BP) ≥140 mmHg or diastolic BP ≥90 mmHg. The JNC–7 defines ‘prehypertension’ to include systolic BP values between 120 and 139 mmHg and diastolic BP values between 80 and 89 mmHg. Individuals with blood pressure in the prehypertension range are clearly at increased risk of developing hypertension in the future and have an increased risk of cardiovascular morbidity and mortality, compared with those with normal BP. However, there is paucity of evidence to intervene in these patients. In this article we discuss an evidence-based approach to therapeutic options in patients with prehypertension.

Prediction of off-target effects on angiotensin-converting enzyme 2

The authors describe a structure-based strategy to identify therapeutically beneficial off-target effects by screening a chemical library of Food and Drug Administration (FDA)-approved small-molecule drugs matching pharmacophores defined for specific target proteins. They applied this strategy to angiotensin-converting enzyme 2 (ACE2), an enzyme that generates vasodilatory peptides and promotes protection from hypertension-associated cardiovascular disease. The conformation-based structural selection method by molecular docking using DOCK allowed them to identify a series of FDA-approved drugs that enhance catalytic efficiency of ACE2 in vitro. These data demonstrate that libraries of approved drugs can be rapidly screened to identify potential side effects due to interactions with specific proteins other than the intended targets.

Are there pleiotropic effects of antihypertensive medications or is it all about the blood pressure in the patient with diabetes and hypertension?

Many small studies with varied surrogate end points and numerous preclinical data have suggested the likelihood of there being specific benefits that exceed simple blood pressure control with drug classes such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and calcium channel blockers, which may be particularly relevant to the patient with diabetes and hypertension. Large clinical trials, however, have provided only token support for this idea. Likewise, meta-analyses that have incorporated varied clinical trials, albeit with somewhat heterogeneous data, have not been particularly forthcoming in their support of this concept. In the patient with diabetes and hypertension, tight blood pressure control, more so than using a specific drug class, is the most important aspect of therapy.

Value of Angiotensin receptor blocker therapy in diabetes

There are more clinical trials investigating angiotensin receptor blockers (ARBs) in diabetes than any other drug class, ranging from early "prevention" trials to the treatment of individuals with advanced organ damage. In its earliest manifestations, visceral adiposity predisposes to hypertension and hyperglycemia (metabolic syndrome). In these individuals, ARB therapy delays the progression to chronic hypertension and may also delay the progression to overt diabetes. Based on the increased cardiovascular disease risk of the metabolic syndrome, which is similar to stage 1 hypertension, both lifestyle modification and ARB therapy are justifiable. ARB therapy has also been found to delay the onset of microalbuminuria and retinopathy. In established diabetic nephropathy, ARB therapy is recommended as a standard alternative to angiotensin-converting enzyme inhibition to reduce macroalbuminuria and delay the progression to end-stage disease. Finally, large trials in ischemic heart disease, heart failure, and stroke have demonstrated clear benefits of ARB therapy. Because ARBs have side effect rates equal to placebo and far lower than any other antihypertensive drug class, the benefit/risk ratio is highly favorable across the entire spectrum of diabetic disease. Thus, ARB therapy is a highly attractive alternative for individuals at any stage of diabetes and with any pattern of complications.

Treatment options for hypertension in high-risk patients

Patients are considered to be at high risk of cardiovascular events if they have diabetes, chronic kidney disease, stroke, established coronary artery disease, or a coronary artery disease equivalent. Blood pressure-lowering therapy has been shown to reduce cardiovascular events in these patients significantly. Identification of high-risk patients by global risk evaluation is recommended for every hypertensive patient. Treatment of hypertension in high-risk patients with an angiotensin-converting enzyme inhibitor or an angiotensin receptor antagonist, with or without addition of a dihydropyridine calcium channel antagonist, is a reasonable approach based on current clinical trials.

Comparative clinical- and cost-effectiveness of candesartan and losartan in the management of hypertension and heart failure: a systematic review, meta- and cost-utility analysis

The UK National Health Service (NHS) currently spends in excess of £250 million per annum on angiotensin II receptor blockers (ARBs) for the treatment of hypertension and heart failure; with candesartan currently dominating the market. With the recent introduction of generic losartan, we set out to directly compare the branded market leader to its now cheaper alternative. The primary objectives were to compare the blood pressure (BP) lowering efficacy and cardiovascular outcomes of candesartan and losartan in the treatment of essential hypertension and chronic heart failure, respectively. The secondary objective was to model their comparative incremental cost-effectiveness in a UK NHS setting. The Cochrane Central Register of Controlled Trials (Cochrane Library 2009, issue 2), which contains the Hypertension and Heart Group's specialist register, Medline (1950-February 2010), and Embase (1980-February 2010) were included in the search strategy. Selection criteria were randomised studies of candesartan versus losartan in adults (> 18 years). The main outcome measures were as follows: Hypertension: mean change from baseline in trough (24 h postdose) systolic and diastolic BP. Heart failure: composite of cardiovascular death and hospital admission for management of heart failure. Two reviewers applied inclusion criteria, assessed trial quality, and extracted data. Eight (three of which met inclusion criteria) and zero trials compared candesartan directly with losartan in the treatment of hypertension and heart failure, respectively. A between-treatment difference of -1.96 mmHg [95% confidence interval (CI) -2.40 to -1.51] for trough diastolic BP and -3.00 mmHg (95% CI -3.79 to -2.22) for trough systolic BP in favour of candesartan was observed. Based on this differential, a 10-year Markov model estimates the cost per quality-adjusted life-year gained to exceed £40,000 for using candesartan in place of generic losartan. Candesartan reduces BP to a slightly greater extent when compared with losartan, however, such difference is unlikely to be cost-effective based on current acquisition costs, perceived NHS affordability thresholds and use of combination regimens. We could find no robust evidence supporting the superiority of candesartan over losartan in the treatment of heart failure. We therefore recommend using generic losartan as the ARB of choice which could save the UK NHS approximately £200 million per annum in drug costs.

Renin-angiotensin system blockade and cognitive function in patients at high risk of cardiovascular disease: analysis of data from the ONTARGET and TRANSCEND studies

BACKGROUND

cardiovascular risk factors are associated with dementia and cognitive decline. We investigated the effects of renin-angiotensin system blockade on cognitive function in patients aged 55 years and older with established atherosclerotic cardiovascular disease or diabetes with end-organ damage in two clinical trials.

METHODS

in the main study, ONTARGET, a double-blind, double-dummy, randomised controlled trial, the effects on cardiovascular outcomes of standard doses of an angiotensin-converting enzyme (ACE) inhibitor (ramipril), an angiotensin-receptor blocker (telmisartan), and a combination of the drugs were evaluated in 25 620 participants. In the parallel TRANSCEND trial, the effects of telmisartan were compared with those of placebo in 5926 participants intolerant to ACE inhibitors. Secondary outcomes included cognitive impairment (defined by investigator-reported diagnosis of dementia or significant cognitive dysfunction, or a score of ≤ 23 on the Mini-Mental State Examination [MMSE]) and cognitive decline (a decrease of ≤ 3 points on the MMSE from baseline during follow-up). Analyses were by intention to treat. We pooled data from these studies to identify baseline predictors of cognitive impairment and its frequency according to mean systolic blood pressure during follow-up. These studies were registered with ClinicalTrials.gov, number NCT00153101.

FINDINGS

During a median duration of 56 months (IQR 51-64) of follow-up in ONTARGET, cognitive impairment occurred in 652 (8%) of 7865 patients allocated ramipril, 584 (7%) of 7797 allocated telmisartan, and 618 (8%) of 7807 allocated combination treatment (combination vs ramipril, odds ratio [OR] 0·95, 95% CI 0·85-1·07, p= 0·39; telmisartan vs ramipril, OR 0·90, 0·80-1·01, p = 0·06). Corresponding figures for cognitive decline were 1314 (17%), 1279 (17%), and 1240 (17%) in each of the groups, respectively (telmisartan vs ramipril, OR 0·97, 0·89-1·06, p= 0·53; combination vs ramipril, OR 0·95, 0·88-1·04, p=0·28). In TRANSCEND, cognitive impairment occurred in 239 (9%) of 2694 participants allocated telmisartan compared with 245 (9%) of 2689 allocated placebo (OR 0·97, 0·81-1·17, p= 0·76). The corresponding figures for cognitive decline were 454 (17%) and 412 (16%; OR 1·10, 0·95-1·27, p= 0·22).

INTERPRETATION

In patients with cardiovascular disease or diabetes, different approaches to blocking of the renin-angiotensin system had no clear effects on cognitive outcomes. Although patients with the lowest systolic blood pressure had the greatest preservation of cognitive function, meta-regression analyses did not show any benefits of blood-pressure lowering on cognition over several years of treatment.