New Molecules for Treating Resistant Hypertension: a Clinical Perspective

PURPOSE OF REVIEW

To review the findings of trials evaluating pharmacological treatment approaches for hypertension in general, and resistant hypertension (RH) in particular, and propose future research and clinical directions.

RECENT FINDINGS

RH is defined as blood pressure (BP) that remains above target levels despite adherence to at least three antihypertensive medications, including a diuretic. Thus far, clinical trials of pharmacological approaches in RH have focused on older molecules, with spironolactone being demonstrated as the most efficacious fourth-line agent. However, the use of spironolactone in clinical practice is hampered by its side effect profile and the risk of hyperkalaemia in important RH subgroups, such as patients with moderate-severe chronic kidney disease (CKD). Clinical trials of new molecules targeting both well-established and more recently elucidated pathophysiologic mechanisms of hypertension offer a multitude of potential treatment avenues that warrant further evaluation in the context of RH. These include selective mineralocorticoid receptor antagonists (MRAs), aldosterone synthase inhibitors (ASIs), activators of the counterregulatory renin-angiotensin-system (RAS), vaccines, neprilysin inhibitors alone and in combined formulations, natriuretic peptide receptor agonists A (NPRA-A) agonists, vasoactive intestinal peptide (VIP) agonists, centrally acting aminopeptidase A (APA|) inhibitors, antimicrobial suppression of central sympathetic outflow (minocycline), dopamine β-hydroxylase (DβH) inhibitors and Na+/H+ Exchanger 3 (NHE3) inhibitors. There is a paucity of data from trials evaluating newer molecules for the treatment of RH. Emergent novel molecules for non-resistant forms of hypertension heighten the prospects of identifying new, effective and well-tolerated pharmacological approaches to RH. There is a glaring need to undertake RH-focused trials evaluating their efficacy and clinical applicability.

Antihypertensive therapy prescribing patterns and correlates of blood pressure control among hypertensive patients with chronic kidney disease

We used electronic health records (EHRs) data from 5658 ambulatory chronic kidney disease (CKD) patients with hypertension and prescribed antihypertensive therapy to examine antihypertensive drug prescribing patterns, blood pressure (BP) control, and risk factors for resistant hypertension (RHTN) in a real-world setting. Two-thirds of CKD patients and three-fourths of those with proteinuria were prescribed guideline-recommended renoprotective agents including an angiotensin-converting enzyme inhibitor (ACEI) or an angiotensin receptor blocker (ARB); however, one-third were not prescribed an ACEI or ARB. CKD patients, particularly those with stages 1-2 CKD, who were prescribed regimens including beta-blocker (BB) + diuretic or ACEI/ARB + BB + diuretic were more likely to have controlled BP (<140/90 mm Hg) compared to those prescribed other combinations. Risk factors for RHTN included African American race and major comorbidities. Clinicians may use these findings to tailor antihypertensive therapy to the needs of each patient, including providing CKD stage-specific treatment, and better identify CKD patients at risk of RHTN.

Characteristics and treatment of African-American and European-American patients with resistant hypertension identified using the electronic health record in an academic health centre: a case-control study

OBJECTIVE

To identify patients with hypertension with resistant and controlled blood pressure (BP) using electronic health records (EHRs) in order to elucidate practices in the real-world clinical treatment of hypertension and to enable future genetic studies.

DESIGN

Using EHRs, we developed and validated algorithms to identify patients with resistant and controlled hypertension.

SETTING

An academic medical centre in Nashville, Tennessee.

POPULATION

European-American (EA) and African-American (AA) patients with hypertension.

MAIN OUTCOME MEASURES

Demographic characteristics: race, age, gender, body mass index, outpatient BPs and the history of diabetes mellitus, chronic kidney disease stage 3, ischaemic heart disease, transient ischaemic attack, atrial fibrillation and sleep apnoea.

MEDICATION TREATMENT

All antihypertensive medication classes prescribed to a patient at the time of classification and ever prescribed following classification.

RESULTS

The algorithms had performance metrics exceeding 92%. The prevalence of resistant hypertension in the total hypertensive population was 7.3% in EA and 10.5% in AA. At diagnosis, AA were younger, heavier, more often female and had a higher incidence of type 2 diabetes and higher BPs than EA. AA with resistant hypertension were more likely to be treated with vasodilators, dihydropyridine calcium channel blockers and alpha-2 agonists while EA were more likely to be treated with angiotensin receptor blockers, renin inhibitors and beta blockers. Mineralocorticoid receptor antagonists use was increased in patients treated with more than four antihypertensive medications compared with patients treated with three (12.4% vs 2.6% in EA, p<0.001; 12.3% vs 2.8% in AA, p<0.001). The number of patients treated with a mineralocorticoid receptor antagonist increased to 37.4% in EA and 41.2% in AA over a mean follow-up period of 7.4 and 8.7 years, respectively.

CONCLUSIONS

Clinical treatment of resistant hypertension differs in EA and AA patients. These results demonstrate the feasibility of identifying resistant hypertension using an EHR.

Dietary Salt Restriction in Chronic Kidney Disease: A Meta-Analysis of Randomized Clinical Trials

Background. A clear evidence on the benefits of reducing salt in people with chronic kidney disease (CKD) is still lacking. Salt restriction in CKD may allow better control of blood pressure (BP) as shown in a previous systematic review while the effect on proteinuria reduction remains poorly investigated. Methods. We performed a meta-analysis of randomized controlled trials (RCTs) evaluating the effects of low versus high salt intake in adult patients with non-dialysis CKD on change in BP, proteinuria and albuminuria. Results. Eleven RCTs were selected and included information about 738 CKD patients (Stage 1–4); urinary sodium excretion was 104 mEq/day (95%CI, 76–131) and 179 mEq/day (95%CI, 165–193) in low- and high-sodium intake subgroups, respectively, with a mean difference of −80 mEq/day (95%CI from −107 to −53; p <0.001). Overall, mean differences in clinic and ambulatory systolic BP were −4.9 mmHg (95%CI from −6.8 to −3.1, p <0.001) and −5.9 mmHg (95%CI from −9.5 to −2.3, p <0.001), respectively, while clinic and ambulatory diastolic BP were −2.3 mmHg (95%CI from −3.5 to −1.2, p <0.001) and −3.0 mmHg (95%CI from −4.3 to −1.7; p <0.001), respectively. Mean differences in proteinuria and albuminuria were −0.39 g/day (95%CI from −0.55 to −0.22, p <0.001) and −0.05 g/day (95%CI from −0.09 to −0.01, p = 0.013). Conclusion. Moderate salt restriction significantly reduces BP and proteinuria/albuminuria in patients with CKD (Stage 1–4).

Resistant and undertreated hypertension in patients with chronic kidney disease: data from the PATRIOTIC survey

BACKGROUND

Hypertension is prevalent in chronic kidney disease (CKD), but the control of hypertension is suboptimal. We reported the prevalence and characteristics of resistant and undertreated hypertension based on a nationwide survey aiming to improve blood pressure (BP) control.

METHODS

Resistant hypertension (RH) was defined as BP above the target (<140/90 mm Hg) despite the use of 3 antihypertensive drugs or achieving the target BP by using ≥4 antihypertensive drugs. Undertreated hypertension was defined as uncontrolled hypertension (unCH) using ≤2 drugs. We compared the characteristics and antihypertensive treatment among different groups (including RH and unCH using ≤2 drugs). Multivariable logistic regression was used to detect factors associated with unCH using ≤2 drugs and RH.

RESULTS

4,435 nondialysis CKD patients with hypertension were analyzed, and 36.9% of participants achieved controlled hypertension (CH) using ≤3 drugs, 11.1% met the criteria for RH, and 52% had unCH despite the use of ≤ 2 antihypertensive drugs. Participants with unCH using ≤ 2 drugs had low usage of renin-angiotensin system blockers (36.8%) and diuretics (5.5%), which was much lower than participants with CH using ≤3 drugs and RH (P< 0.05). After multivariable adjustment, obesity, advanced CKD stages, urinary protein level of ≥1.5 g/24 h, diabetes, and cardiovascular disease were associated with RH in CKD patients (P< 0.05).

CONCLUSION

Compared with RH, undertreated hypertension contributes more to the unCH in Chinese CKD patients. It is important to ensure adequate antihypertensive treatment, including choosing antihypertensive drugs, that guidelines recommended.

Chronic Kidney Disease As a Potential Indication for Renal Denervation

Renal denervation is being used as a blood pressure lowering therapy for patients with apparent treatment resistant hypertension. However, this population does not represent a distinct disease condition in which benefit is predictable. In fact, the wide range in effectiveness of renal denervation could be a consequence of this heterogeneous pathogenesis of hypertension. Since renal denervation aims at disrupting sympathetic nerves surrounding the renal arteries, it seems obvious to focus on patients with increased afferent and/or efferent renal sympathetic nerve activity. In this review will be argued, from both a pathophysiological and a clinical point of view, that chronic kidney disease is particularly suited to renal denervation.

Obesity, Renin-Angiotensin System Blockade and Risk of Adverse Renal Outcomes: A Population-Based Cohort Study

BACKGROUND

Obesity substantially increases the risk of the development of chronic kidney disease. Adipose tissue expresses all of the components of the renin-angiotensin system (RAS), contributing to the high prevalence of hypertension in obese patients and driving renal hyperfiltration and subsequent glomerular injury.

METHODS

We performed a retrospective cohort study using a United Kingdom primary care database, evaluating the effect of time-updated exposure to RAS blockade versus all other antihypertensive medications in obese, hypertensive, non-diabetic patients. We used Cox proportional hazards modeling with and without marginal structural modeling to assess the hazards of developing a primary outcome of 50% reduction in estimated glomerular filtration rate (eGFR) (across 2 consecutive values), end stage renal disease or death.

RESULTS

A total of 219,701 patients met inclusion criteria, with a median 7.2 years of follow-up. Median baseline eGFR was 72.6 ml/min/1.73 m2. Compared to other antihypertensive medications, patients treated with RAS blockade had a modestly elevated hazard of adverse renal outcomes using traditional Cox regression (hazard ratio (HR) 1.04, 95% CI 1.01-1.07) and no significantly increased hazard by marginal structural modeling (HR 1.02, 95% CI 0.97-1.08). Patients treated with RAS blockade had a significantly reduced hazard of incident diabetes, but no significant difference in mortality.

CONCLUSION

This study, conducted in a large real-world cohort, provides evidence that RAS blockade may not provide benefit with regard to longitudinal renal outcomes in obese, hypertensive patients. Further research is needed to elucidate the hemodynamic and renoprotective role of antihypertensive medications in obese patients.

Apparent treatment-resistant hypertension and chronic kidney disease: another cardiovascular-renal syndrome?

To identify patients at increased risk of cardiovascular (CV) outcomes, apparent treatment-resistant hypertension (aTRH) is defined as having a blood pressure above goal despite the use of 3 or more antihypertensive therapies of different classes at maximally tolerated doses, ideally including a diuretic. Recent epidemiologic studies in selected populations estimated the prevalence of aTRH as 10% to 15% among patients with hypertension and that aTRH is associated with elevated risk of CV and renal outcomes. Additionally, aTRH and CKD are associated. Although the pathogenesis of aTRH is multifactorial, the kidney is believed to play a significant role. Increased volume expansion, aldosterone concentration, mineralocorticoid receptor activity, arterial stiffness, and sympathetic nervous system activity are central to the pathogenesis of aTRH and are targets of therapies. Although diuretics form the basis of therapy in aTRH, pathophysiologic and clinical data suggest an important role for aldosterone antagonism. Interventional techniques, such as renal denervation and carotid baroreceptor activation, modulate the sympathetic nervous system and are currently in phase III trials for the treatment of aTRH. These technologies are as yet unproven and have not been investigated in relationship to CV outcomes or in patients with CKD.

The prevalence, incidence, prognosis, and associated conditions of resistant hypertension

Resistant hypertension is a relevant condition gaining special attention given its clinical and economic impact. Although the true prevalence is unknown, clinical trials and population-based studies have shown that it is a common clinical problem that likely will increase in incidence with an aging and more obese population. A complex interaction of various risk factors including lifestyle, associated conditions, and identifiable secondary causes can lead to uncontrolled hypertension. Important factors including improper blood pressure measuring technique, poor medication adherence, and the white coat phenomenon can lead to pseudoresistance, or a false impression of treatment resistance, which must be excluded. Patients with true resistant hypertension have a greater risk for developing adverse cardiovascular events compared with those with controlled blood pressure, leading to an unfavorable prognosis without adequate treatment. This article reviews the current understanding of the epidemiology of resistant hypertension.

Incident ESRD and treatment-resistant hypertension: the reasons for geographic and racial differences in stroke (REGARDS) study

BACKGROUND

Studies suggest that treatment-resistant hypertension is common and increasing in prevalence among US adults. Although hypertension is a risk factor for end-stage renal disease (ESRD), few data are available for the association between treatment-resistant hypertension and ESRD risk.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

We analyzed data from 9,974 REGARDS (Reasons for Geographic and Racial Differences in Stroke) Study participants treated for hypertension without ESRD at baseline.

PREDICTOR

Treatment-resistant hypertension was defined as uncontrolled blood pressure (BP) with concurrent use of 3 antihypertensive medication classes including a diuretic or use of 4 or more antihypertensive medication classes including a diuretic regardless of BP.

OUTCOME

Incident ESRD was identified by linkage of REGARDS Study participants with the US Renal Data System.

MEASUREMENTS

During a baseline in-home study visit, BP was measured twice and classes of antihypertensive medication being taken were determined by pill bottle inspection.

RESULTS

During a median follow-up of 6.4 years, there were 152 incident cases of ESRD (110 ESRD cases among 2,147 with treatment-resistant hypertension and 42 ESRD cases among 7,827 without treatment-resistant hypertension). The incidence of ESRD per 1,000 person-years for hypertensive participants with and without treatment-resistant hypertension was 8.86 (95% CI, 7.35-10.68) and 0.88 (95% CI, 0.65-1.19), respectively. After multivariable adjustment, the HR for ESRD comparing hypertensive participants with versus without treatment-resistant hypertension was 6.32 (95% CI, 4.30-9.30). Of participants who developed incident ESRD during follow-up, 72% had treatment-resistant hypertension at baseline.

LIMITATIONS

BP, estimated glomerular filtration rate, and albuminuria assessed at a single time.

CONCLUSIONS

Individuals with treatment-resistant hypertension are at increased risk for ESRD. Appropriate clinical management strategies are needed to treat treatment-resistant hypertension in order to preserve kidney function in this high-risk group.

Definition, identification and treatment of resistant hypertension in chronic kidney disease patients

Resistant hypertension, the inability to achieve goal blood pressure despite the use of three or more appropriately dosed antihypertensive drugs (including a diuretic), remains a common clinical problem, especially in patients with chronic kidney disease (CKD). While the exact prevalence and prognosis of resistant hypertension in CKD patients remain unknown, resistant hypertension likely contributes significantly to increased cardiovascular risk and progression of kidney disease in this population. We review the identification and evaluation of patients with resistant hypertension, including the importance of 24-h ambulatory blood pressure monitoring in the identification of 'white-coat', 'masked' and 'non-dipper' hypertension, the latter of which has particular clinical and therapeutic importance in patients with resistant hypertension and CKD. We then discuss treatment strategies for resistant hypertension that target the pathophysiologic mechanisms underlying resistance to treatment, including persistent volume excess, incomplete renin-angiotensin-aldosterone system blockade and inadequate nocturnal blood pressure control. Finally, we propose a treatment algorithm for evaluation and treatment of resistant hypertension in patients with CKD.

Prevalence of apparent treatment-resistant hypertension among individuals with CKD

BACKGROUND AND OBJECTIVES

Apparent treatment-resistant hypertension is defined as systolic/diastolic BP ≥ 140/90 mmHg with concurrent use of three or more antihypertensive medication classes or use of four or more antihypertensive medication classes regardless of BP level.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The prevalence of apparent treatment-resistant hypertension among Reasons for Geographic and Racial Differences in Stroke study participants treated for hypertension (n=10,700) was determined by level of estimated GFR and albumin-to-creatinine ratio, and correlates of apparent treatment-resistant hypertension among those participants with CKD were evaluated. CKD was defined as an albumin-to-creatinine ratio ≥ 30 mg/g or estimated GFR<60 ml/min per 1.73 m(2).

RESULTS

The prevalence of apparent treatment-resistant hypertension was 15.8%, 24.9%, and 33.4% for those participants with estimated GFR ≥ 60, 45-59, and <45 ml/min per 1.73 m(2), respectively, and 12.1%, 20.8%, 27.7%, and 48.3% for albumin-to-creatinine ratio<10, 10-29, 30-299, and ≥ 300 mg/g, respectively. The multivariable-adjusted prevalence ratios (95% confidence intervals) for apparent treatment-resistant hypertension were 1.25 (1.11 to 1.41) and 1.20 (1.04 to 1.37) for estimated GFR levels of 45-59 and <45 ml/min per 1.73 m(2), respectively, versus ≥ 60 ml/min per 1.73 m(2) and 1.54 (1.39 to 1.71), 1.76 (1.57 to 1.97), and 2.44 (2.12 to 2.81) for albumin-to-creatinine ratio levels of 10-29, 30-299, and ≥ 300 mg/g, respectively, versus albumin-to-creatinine ratio<10 mg/g. After multivariable adjustment, men, black race, larger waist circumference, diabetes, history of myocardial infarction or stroke, statin use, and lower estimated GFR and higher albumin-to-creatinine ratio levels were associated with apparent treatment-resistant hypertension among individuals with CKD.

CONCLUSIONS

This study highlights the high prevalence of apparent treatment-resistant hypertension among individuals with CKD.

Prevalence and prognostic role of resistant hypertension in chronic kidney disease patients

OBJECTIVES

This study sought to evaluate in chronic kidney disease (CKD) prevalence and prognosis of true resistant hypertension (RH) (i.e., confirmed by ambulatory blood pressure [ABP] monitoring).

BACKGROUND

In CKD, uncontrolled hypertension is a major risk factor, but no study has properly investigated the role of RH.

METHODS

We prospectively studied 436 hypertensive CKD patients under nephrology care. Four groups were constituted by combining 24-h ABP with diagnosis of RH (office blood pressure ≥130/80 mm Hg, despite adherence to ≥3 full-dose antihypertensive drugs including a diuretic agent or ≥4 drugs): control (ABP <125/75 mm Hg without RH); pseudoresistance (ABP <125/75 mm Hg with RH); sustained hypertension (ABP ≥125/75 mm Hg without RH); and true resistance (ABP ≥125/75 mm Hg with RH). Endpoints of survival analysis were renal (end-stage renal disease or death) and cardiovascular events (fatal and nonfatal cardiovascular event).

RESULTS

Age was 65 ± 14 years, men 58%, diabetes 36%, cardiovascular disease 30%, median proteinuria 0.24 (interquartile range 0.09 to 0.83) g/day, estimated glomerular filtration rate 43 ± 20 ml/min/1.73 m(2), office blood pressure 146 ± 19/82 ± 12 mm Hg, and 24-h ABP 129 ± 17/72 ± 10 mm Hg. True resistant patients were 22.9%, and pseudoresistant patients were 7.1%, whereas patients with sustained hypertension were 42.9%, and control subjects were 27.1%. Over 57 months of follow-up, 109 cardiovascular events and 165 renal events occurred. Cardiovascular risk (hazard ratio [95% confidence interval]) was 1.24 (0.55 to 2.78) in pseudoresistance, 1.11 (0.67 to 1.84) in sustained hypertension, and 1.98 (1.14 to 3.43) in true resistance, compared with control subjects. Corresponding hazards for renal events were 1.18 (0.45 to 3.13), 2.14 (1.35 to 3.40), and 2.66 (1.62 to 4.37).

CONCLUSIONS

In CKD, pseudoresistance is not associated with an increased cardio-renal risk, and sustained hypertension predicts only renal outcome. True resistance is prevalent and identifies patients carrying the highest cardiovascular risk.

Resistant hypertension in nondialysis chronic kidney disease

Resistant hypertension (RH) is defined as blood pressure (BP) that remains above the target of less than 140/90 mmHg in the general population and 130/80 mmHg in people with diabetes mellitus or chronic kidney disease (CKD) in spite of the use of at least three full-dose antihypertensive drugs including a diuretic or as BP that reaches the target by means of four or more drugs. In CKD, RH is a common condition due to a combination of factors including sodium retention, increased activity of the renin-angiotensin system, and enhanced activity of the sympathetic nervous system. Before defining the hypertensive patient as resistant it is mandatory to exclude the so-called “pseudoresistance.” This condition, which refers to the apparent failure to reach BP target in spite of an appropriate antihypertensive treatment, is mainly caused by white coat hypertension that is prevalent (30%) in CKD patients. Recently we have demonstrated that “true” RH represents an independent risk factor for renal and cardiovascular outcomes in CKD patients.

What is the prevalence of resistant hypertension in the United States?

PURPOSE OF REVIEW

Resistant hypertension, defined as blood pressure uncontrolled on three, or controlled with at least four, antihypertensive agents (including a diuretic), is associated with higher risk of secondary hypertension, cardiovascular and renal events, and increased healthcare expenditures. Until recently, however, the prevalence of resistant hypertension in the United States (US) was based on clinical trial registries or pharmacy databases.

RECENT FINDINGS

Recent analyses of National Health and Nutrition Examination Survey (NHANES) data, drawn from representative samples of the adult, noninstitutionalized, civilian population, have estimated the prevalence of resistant hypertension at 8.9  ±  0.6% of the US hypertensive population in 2003-2008. A time-sequence comparison of NHANES data from 1998 through 2008 suggests that, unlike hypertension, resistant hypertension is becoming more prevalent (e.g., 20.7% in 2005-2008), due to aging and increased obesity in the general population. Resistant hypertension was more frequent in people who were older, obese, male, African American or nonblack Hispanic.

SUMMARY

In coming years, even if the prevalence of hypertension remains stable, resistant hypertension is likely to increase, especially as the proportion of treated hypertension increases. Because of increased use of healthcare resources, resistant hypertensive patients should be identified early, and greater efforts made to control their blood pressures.