Refractory hypertension: definition, prevalence, and patient characteristics

Options for patients with out-of-control blood pressure: after all avenues have been exhausted

INTRODUCTION

Uncontrolled hypertension is the leading risk factor for global mortality. Most hypertensive patients can be controlled with standard medication combinations, but some may not respond adequately to ≥3 or even to ≥5 antihypertensive agents.

AREAS COVERED

In this review, we summarize the recent literature on difficult-to-treat hypertension identified by a Medline search, and we discuss the options for fourth line and subsequent therapy.

EXPERT OPINION

It is essential to confirm resistant hypertension with out-of-office blood pressure measurements and to consider lifestyle factors, adherence to medication and secondary causes of hypertension. When true resistant hypertension is confirmed and blood pressure is not controlled with an optimal triple combination, preferably as a fixed dose combination tablet, spironolactone is usually recommended as the fourth medication. Comorbid conditions should be treated as appropriate with sodium-glucose-cotransporter 2 inhibitors, glucagon-like peptide-1 receptor agonists, sacubitril-valsartan or finerenone. Renal denervation appears to be a useful addition to overcome some of the problems of medication adherence. The endothelin antagonist aprocitentan may be a final option in some countries. Of the drugs in development, the RNA based therapeutics that inhibit angiotensinogen synthesis appear to be some of the most promising.

Diagnosis and management of resistant hypertension

Resistant hypertension is defined as blood pressure that remains above the therapeutic goal despite concurrent use of at least three antihypertensive agents of different classes, including a diuretic, with all agents administered at maximum or maximally tolerated doses. Resistant hypertension is also diagnosed if blood pressure control requires four or more antihypertensive drugs. Assessment requires the exclusion of apparent treatment resistant hypertension, which is most often the result of non-adherence to treatment. Resistant hypertension is associated with major cardiovascular events in the short and long term, including heart failure, ischemic heart disease, stroke, and renal failure. Guidelines from several professional organizations recommend lifestyle modification and antihypertensive drugs. Medications typically include an angiotensin converting enzyme inhibitor or angiotensin receptor blocker, a calcium channel blocker, and a long acting thiazide-type/like diuretic; if a fourth drug is needed, evidence supports addition of a mineralocorticoid receptor antagonist. After a long pause since 2007 when the last antihypertensive class was approved, several novel agents are now under active development. Some of these may provide potent blood pressure lowering in broad groups of patients, such as aldosterone synthase inhibitors and dual endothelin receptor antagonists, whereas others may provide benefit by allowing treatment of resistant hypertension in special populations, such as non-steroidal mineralocorticoid receptor antagonists in patients with chronic kidney disease. Several device based approaches have been tested, with renal denervation being the best supported and only approved interventional device treatment for resistant hypertension.

Resistant hypertension: Diagnosis, evaluation, and treatment practical approach

The term RH describes a subgroup of hypertensive patients whose BP is uncontrolled despite the use of at least three antihypertensive drugs in an appropriate combination at optimal or best tolerated doses. True RH is considered when appropriate lifestyle measures and treatment with optimal or best tolerated doses of three or more drugs (a thiazide/thiazide-like diuretic, plus renin-angiotensin system -RAS- blocker and a calcium channel blocker -CCB-) fail to lower office BP to <140/90 mmHg; besides the inadequate BP control should be confirmed by home blood pressure monitoring (HBPM) or 24-hour ambulatory; and evidence of adherence to therapy and exclusion of secondary causes of hypertension are required. RH patients are at a high risk of cardiovascular events and death. RH is associated with a higher prevalence of end-organ damage. When stricter criteria are applied, a reasonable estimate of the prevalence of true RH is 5 % of the total hypertensive population. The predominant hemodynamic pattern appears to be increased systemic vascular resistance and plasma volume with normal or even low cardiac output. We must rule out pseudo-resistance before diagnosing true drug resistance. RH is a therapeutic challenge, and its management includes lifestyle interventions, avoiding nonadherence to treatment, avoiding inertia, appropriate use of antihypertensive drugs based on current evidence, especially long-acting diuretics, and the addition of mineralocorticoid receptor antagonists. RCTs to identify the most protective medical therapy in RH are needed. A series of drugs in different stages of investigation could significantly impact RH treatment in the future.

Cellular Senescence in Cardiovascular Diseases: From Pathogenesis to Therapeutic Challenges

Cellular senescence (CS), classically considered a stable cell cycle withdrawal, is hallmarked by a progressive decrease in cell growth, differentiation, and biological activities. Senescent cells (SNCs) display a complicated senescence-associated secretory phenotype (SASP), encompassing a variety of pro-inflammatory factors that exert influence on the biology of both the cell and surrounding tissue. Among global mortality causes, cardiovascular diseases (CVDs) stand out, significantly impacting the living quality and functional abilities of patients. Recent data suggest the accumulation of SNCs in aged or diseased cardiovascular systems, suggesting their potential role in impairing cardiovascular function. CS operates as a double-edged sword: while it can stimulate the restoration of organs under physiological conditions, it can also participate in organ and tissue dysfunction and pave the way for multiple chronic diseases under pathological states. This review explores the mechanisms that underlie CS and delves into the distinctive features that characterize SNCs. Furthermore, we describe the involvement of SNCs in the progression of CVDs. Finally, the study provides a summary of emerging interventions that either promote or suppress senescence and discusses their therapeutic potential in CVDs.

Apparent treatment-resistant hypertension associated lifetime cardiovascular risk in a longitudinal national registry

AIMS

Apparent treatment-resistant hypertension (aRH), wherein blood pressure elevation requires treatment with multiple medications, is associated with adverse cardiovascular events over the short-term. We sought to evaluate the degree of excess risk associated with aRH across the lifespan.

METHODS AND RESULTS

We identified all individuals with hypertension who were prescribed at least one anti-hypertensive medication from the FinnGen Study, a cohort of randomly selected individuals across Finland. We then identified the maximum number of concurrently prescribed anti-hypertensive medication classes prior to age 55 and classified those co-prescribed ≥4 anti-hypertensive medication classes as aRH. Using multivariable adjusted Cox proportional hazards models, we assessed the association of aRH well as the number of co-prescribed anti-hypertensive classes with cardiorenal outcomes across the lifespan. Among 48 721 hypertensive individuals, 5715 (11.7%) met the aRH criteria. Compared to those prescribed only one anti-hypertensive medication class, the lifetime risk of renal failure increased with the addition of each additional medication class, beginning with the second, while the risk of heart failure and ischaemic stroke increased after addition of the third drug class. Similarly, those with aRH suffered increased risk of renal failure (hazard ratio 2.30, 95% CI 2.00-2.65), intracranial haemorrhage (1.50, 1.08-2.05), heart failure (1.40, 1.24-1.63) cardiac death (1.79, 1.45-2.21), and all-cause death (1.76, 1.52-2.04).

CONCLUSION

Among individuals with hypertension, aRH that develops prior to mid-life is associated with substantially elevated cardiorenal disease risk across the lifespan.

When blood pressure refuses to budge: exploring the complexity of resistant hypertension

Resistant hypertension, defined as blood pressure that remains above goal despite using three or more antihypertensive medications, including a diuretic, affects a significant proportion of the hypertensive population and is associated with increased cardiovascular morbidity and mortality. Despite the availability of a wide range of pharmacological therapies, achieving optimal blood pressure control in patients with resistant hypertension remains a significant challenge. However, recent advances in the field have identified several promising treatment options, including spironolactone, mineralocorticoid receptor antagonists, and renal denervation. In addition, personalized management approaches based on genetic and other biomarkers may offer new opportunities to tailor therapy and improve outcomes. This review aims to provide an overview of the current state of knowledge regarding managing resistant hypertension, including the epidemiology, pathophysiology, and clinical implications of the condition, as well as the latest developments in therapeutic strategies and future prospects.

Insight on Efficacy of Renal Artery Denervation for Refractory Hypertension with Chronic Kidney Diseases: A Long-Term Follow-Up of 24-Hour Ambulatory Blood Pressure

Aims

To explore the long-term efficacy and safety of renal denervation in patients with RHT and CKD, a post hoc analysis of eGFR subgroups was completed.

Methods

Fifty-four patients with refractory hypertension with chronic kidney disease were treated with RDN and enrolled in the study. Patients were divided into three groups according to eGFR: eGFR 46–90 ml/min group, eGFR 15–45 ml/min group, and eGFR <15 ml/min group. The planned follow-up period was 48 months to assess 24 h ambulatory blood pressure, renal function, type of antihypertensive medication, and RDN complications.

Results

The ablation sites of the GFR 46–90 ml/min group and GFR 15–45 ml/min group were 32.57 ± 2.99 and 29.53 ± 5.47, respectively. No complications occurred in the GFR 46–90 ml/min group. The GFR<15 ml/min group was treated with 27.07 ± 5.59  ablation. Renal artery dissection occurred in each group of GFR 15–45 ml/min and GFR <15 ml/min. And renal stent implantation artery was performed on these two patients. No severe renal artery stenosis occurred. There were no significant differences in Scr and eGFR between the three groups at each follow-up point. Compared with baseline, SBP was significantly of each group decreased to varying degrees at each follow-up time point. SBP decreased most in the GFR 46–90 ml/min group. Compared with baseline, the type of antihypertensive drugs used in the GFR46-90 ml/min group decreased significantly except for 36 and 48 months. At 48 months' postadmission, there was a significant decrease in the type of antihypertensive medication used in the GFR15-45 ml/min group, and there was no significant decrease in the type of antihypertensive medication used in the GFR<15 ml/min group.

Conclusions

RDN can safely reduce SBP in CKD patients combined with RHT for 48 months, with the most pronounced reduction in the GFR15-45 ml/min group. The variety of antihypertensive drugs was significantly reduced after RDN. This was particularly evident in patients with GFR 15–45 ml/min.

Pathophysiology and genetics of salt-sensitive hypertension

Most hypertensive cases are primary and heavily associated with modifiable risk factors like salt intake. Evidence suggests that even small reductions in salt consumption reduce blood pressure in all age groups. In that regard, the ACC/AHA described a distinct set of individuals who exhibit salt-sensitivity, regardless of their hypertensive status. Data has shown that salt-sensitivity is an independent risk factor for cardiovascular events and mortality. However, despite extensive research, the pathogenesis of salt-sensitive hypertension is still unclear and tremendously challenged by its multifactorial etiology, complicated genetic influences, and the unavailability of a diagnostic tool. So far, the important roles of the renin-angiotensin-aldosterone system, sympathetic nervous system, and immune system in the pathogenesis of salt-sensitive hypertension have been studied. In the first part of this review, we focus on how the systems mentioned above are aberrantly regulated in salt-sensitive hypertension. We follow this with an emphasis on genetic variants in those systems that are associated with and/or increase predisposition to salt-sensitivity in humans.

Prevalence and associated factors of obstructive sleep apnea in refractory hypertension

BACKGROUND

Refractory hypertension (RfHT) and obstructive sleep apnea (OSA) share common pathophysiological mechanisms and probably are intrinsically associated, but their prevalence, clinical profile, and polysomnography (PSG) pattern remain misunderstood.

OBJECTIVE

To describe OSA prevalence and PSG pattern of patients with RfHT in a large cohort of resistant hypertension (RHT).

METHODS

This is a cross-sectional study involving 418 RHT patients (30.9% male; mean age of 62.5 ± 9.9 years) who were submitted to full-night PSG. RfHT was defined as uncontrolled ambulatory blood pressure monitoring using five or more antihypertensive drugs, including spironolactone. Bivariate analysis compared RHT and RfHT and multivariate analysis was performed to assess the independent correlates of OSA.

RESULTS

A total of 90 patients (21.5%) were diagnosed with RfHT (26.7% male; mean age of 58.5 ± 8.3 years). In comparison with resistant ones, RfHT patients were younger, with higher smoking and previous cardiovascular diseases prevalence, especially stroke. There was no difference regarding anthropometric measures. OSA prevalence (80.0 vs. 82.9%) and moderate/severe OSA (51.1 vs. 57.0%) were similar in both groups as well as apnea-hypopnea index. In its turn, refractory hypertensive patients presented better sleep efficiency (78 vs. 71%), with higher total sleep time (315 vs. 281 min) and lower sleep latency (11 vs. 17 min). There was no difference regarding rapid eye movement sleep, oxygen saturation, microarousals index, and periodic limb movement.

CONCLUSION

In this large RHT cohort, resistant and refractory hypertensive patients have similar OSA prevalence, although refractory ones, which by definition use spironolactone, are younger and apparently have a better sleep pattern.

An Update on Refractory Hypertension

Purpose of Review

To update on definition, diagnosis, prevalence, patient characteristics, pathophysiology, and treatment of refractory hypertension (RfHTN).

Recent Findings

Refractory hypertension (RfHTN) is defined as blood pressure (BP) that is uncontrolled despite using ≥ 5 antihypertensive medications of different classes, including a long-acting thiazide diuretic and a mineralocorticoid receptor antagonist (MRA) at maximal or maximally tolerated doses. This new phenotype is different from resistant hypertension (RHTN), defined as BP that is uncontrolled despite using ≥ 3 medications, commonly a long-acting calcium channel blocker (CCB), a blocker of the renin-angiotensin system (angiotensin-converting enzyme [ACE] inhibitor or angiotensin receptor blocker [ARB]), and a diuretic. The RHTN phenotype includes controlled RHTN, BP that is controlled on 4 or more medications. RfHTN is largely attributable to increased sympathetic activity, unlike RHTN, which is mainly due to increased intravascular fluid volume frequently caused by hyperaldosteronism and chronic excessive sodium ingestion. Compared to those with controlled RHTN, patients with RfHTN have a higher prevalence of target organ damage and do not have elevated aldosterone levels. Ongoing clinical trials are assessing the safety and efficacy of using devices to aid with BP control in patients with RfHTN.

Summary

RfHTN is a separate entity from RHTN and is generally attributable to increased sympathetic activity.

Refractory Hypertension: a Narrative Systematic Review with Emphasis on Prognosis

PURPOSE OF REVIEW

To perform a narrative systematic review on refractory hypertension (RfHT) with particular emphasis on prognosis.

RECENT FINDINGS

There were 37 articles on RfHT, 13 non-systematic reviews, and 24 original studies. RfHT, a recently described extreme phenotype of anti-hypertensive treatment failure, shall be defined as uncontrolled out-of-office blood pressure (BP) levels despite the use of at least 5 anti-hypertensive drugs, including a long-acting diuretic and a mineraloreceptor antagonist. Its prevalence ranges from 0.5 to 4.3% of general treated hypertensives and between 3.6 and 51.4% of patients with resistant hypertension (RHT). RfHT is associated with younger age, African ancestry, obesity, hypertension-mediated organ damage and clinical cardiovascular diseases, and with some comorbidities, such as diabetes and obstructive sleep apnea. Its physiopathological mechanisms probably involve sympathetic overactivity and not volume overload. Patients with RfHT have a worse prognosis than non-refractory RHT individuals, with higher risks of adverse cardiovascular and renal outcomes and of mortality. RfHT represents a rare but true extreme phenotype of anti-hypertensive treatment failure distinct from RHT and with a significantly worse prognosis. Identifying such individuals is important to tailor specific interventions.

The incidence of cardiovascular and cerebrovascular complications in patients with uncontrolled hypertension

Aim. To assess the incidence of cardiovascular and cerebrovascular events in patients with controlled and uncontrolled hypertension, controlled resistant and uncontrolled resistant hypertension, refractory hypertension, and probably resistant and probably refractory hypertension. Materials and methods. A telephone call was made to 256 patients with hypertension included in the database to assess the incidence of cardiovascular and cerebrovascular diseases. All responding patients were divided into 7 groups according to the classification of hypertension based on the achievement/non-achievement of target blood pressure values and the number of drugs taken (controlled and uncontrolled hypertension, controlled resistant and uncontrolled resistant hypertension, refractory hypertension, and probably resistant and probably refractory hypertension). The target blood pressure was considered to be less than 140/90 mm Hg. Patients not adhering to medication were not included in the analysis. Results. The group of controlled hypertension included 146 (57%) patients out of 256, controlled resistant hypertension 36 (14%) patients, uncontrolled hypertension 6 (2.3%) patients, resistant uncontrolled hypertension 22 (8.6%) patients, refractory hypertension 31 (12.1%) patients. The group of probably resistant hypertension 6 (2.3%) patients, probably refractory hypertension 9 (3.5%) patients. Of the 28 events that occurred, 6 were attributed to coronary artery disease (including 3 acute myocardial infarction and 2 coronary artery stenting), 3 strokes, 6 episodes of transient ischemic attack and 10 new cases of atrial fibrillation, and 2 patients had sudden cardiac death. Significantly more often, patients with refractory hypertension developed any event compared with patients with controlled (38.7% versus 3.4%; p=0.005) and resistant hypertension (38.7% versus 13.6%; p=0.04). Also, patients from the group of probably refractory hypertension were more likely to develop events than patients with controlled hypertension (33.3% versus 3.4%; p=0.045). Patients with probably refractory hypertension significantly more often had a stroke than patients with controlled hypertension (22.2% versus 0%; p0.05), and patients with refractory hypertension significantly more often had a transient ischemic attack compared with patients from the group of controlled hypertension (12.9% versus 0.7%; p=0.03). Conclusion. Patients with refractory and probably refractory hypertension are significantly more likely to develop cardiovascular and cerebrovascular complications than patients with controlled hypertension.

Prevalence of primary aldosteronism and association with cardiovascular complications in patients with resistant and refractory hypertension

OBJECTIVES

To assess the prevalence of primary aldosteronism and its association with cardiometabolic complications in patients with resistant and refractory hypertension.

METHODS

One hundred and ten consecutive patients with true resistant hypertension [insufficient blood pressure control despite appropriate lifestyle measures and treatment with at least three classes of antihypertensive medication, including a diuretic] and without previous cardiovascular events were screened for secondary hypertension. Refractory hypertension was diagnosed in case of uncontrolled blood pressure despite the use of at least five antihypertensive drugs.

RESULTS

Primary aldosteronism was diagnosed in 32 cases (29.1%). The multivariate analysis showed that primary aldosteronism is a strong factor positively associated with left ventricular hypertrophy [odds ratio (OR) = 12.98, 95% confidence interval (CI) 3.82-60.88; P < 0.001], microalbuminuria (OR = 3.67, 95% CI 1.44-9.78; P = 0.007), carotid intima-media thickness at least 0.9 mm (OR = 2.69, 95% CI 1.02-7.82; P = 0.037), aortic ectasia (OR = 4.08, 95% CI 1,18-15.04; P = 0.027) and atrial fibrillation (OR 8.80, 95% CI 1.53-73.98; P = 0.022). Moreover, primary aldosteronism was independently associated with the presence of at least one (OR = 8.60, 95% CI 1.73-69.88; P = 0.018) and at least two types of organ damage (OR = 3.08, 95% CI 1.19-8.24; P = 0.022). Thirteen patients (11.8%) were affected by refractory hypertension. This group was characterized by significantly higher values of carotid intima-media thickness, higher rate of aldosterone-producing adenoma and atrial fibrillation, compared with the other individuals with resistant hypertension.

CONCLUSION

The current study indicates that primary aldosteronism is a frequent cause of secondary hypertension and cardiovascular complications among patients with resistant and refractory hypertension, suggesting a crucial role of aldosterone in the pathogenesis of severe hypertensive phenotypes and cardiovascular disease.

Hypertension in Chronic Kidney Disease (CKD): Diagnosis, Classification, and Therapeutic Targets

Blood pressure (BP) in the office is often recorded without standardization of the technique of measurement. When office BP measurement is performed with a research-grade methodology, it can inform better therapeutic decisions. The reference-standard method of ambulatory BP monitoring (ABPM) together with the assessment of BP in the office enables the identification of white-coat and masked hypertension, facilitating the stratification of cardiorenal risk. Compared with general population, the prevalence of resistant hypertension is 2- to 3-fold higher among patients with chronic kidney disease (CKD). The use of ABPM is mandatory in order to exclude the white-coat effect, a common cause of pseudoresistance, and confirm the diagnosis of true-resistant hypertension. After the premature termination of Systolic Blood Pressure Intervention Trial due to an impressive cardioprotective benefit of intensive BP-lowering, the 2017 American Heart Association/American College of Cardiology guideline reappraised the definition of hypertension and recommended a tighter BP target of <130/80 mm Hg for the majority of adults with a high cardiovascular risk profile, inclusive of patients with CKD. However, the benefit/risk ratio of intensive BP-lowering in particular subsets of patients with CKD (i.e., those with diabetes or more advanced CKD) continues to be debated. We explore the controversial issue of BP targets in CKD, providing a critical evaluation of the available clinical-trial evidence and guideline recommendations. We argue that the systolic BP target in CKD, if BP is measured correctly, should be <120 mm Hg.

Hypertension: Do Inflammation and Immunity Hold the Key to Solving this Epidemic?

Elevated cardiovascular risk including stroke, heart failure, and heart attack is present even after normalization of blood pressure in patients with hypertension. Underlying immune cell activation is a likely culprit. Although immune cells are important for protection against invading pathogens, their chronic overactivation may lead to tissue damage and high blood pressure. Triggers that may initiate immune activation include viral infections, autoimmunity, and lifestyle factors such as excess dietary salt. These conditions activate the immune system either directly or through their impact on the gut microbiome, which ultimately produces chronic inflammation and hypertension. T cells are central to the immune responses contributing to hypertension. They are activated in part by binding specific antigens that are presented in major histocompatibility complex molecules on professional antigen-presenting cells, and they generate repertoires of rearranged T-cell receptors. Activated T cells infiltrate tissues and produce cytokines including interleukin 17A, which promote renal and vascular dysfunction and end-organ damage leading to hypertension. In this comprehensive review, we highlight environmental, genetic, and microbial associated mechanisms contributing to both innate and adaptive immune cell activation leading to hypertension. Targeting the underlying chronic immune cell activation in hypertension has the potential to mitigate the excess cardiovascular risk associated with this common and deadly disease.

Refractory and Resistant Hypertension in Patients with Type 2 Diabetes Mellitus: Different Response to Renal Denervation

Aim      To compare the antihypertensive effectivity of renal denervation in patients with diabetes mellitus (DM) and associated refractory arterial hypertension (rfAH) (treated with 5 or more classes of antihypertensive drugs, including a thiazide diuretic and a mineralocorticoid receptor antagonist) and uncontrolled resistant AH (ucAH) (treated with 3-4 drugs).Material and methods  This interventional study with renal denervation included 18 DM patients with rfAH and 40 DM patients with ucAH; 16 and 36 of them, respectively, completed the study in 6 months. At baseline, patients were sex- and age-matched. Study methods included measurement of office blood pressure (BP; systolic/diastolic BP, SBP/DBP); outpatient BP monitoring; evaluation of kidney function (estimated glomerular filtration rate by the CKD-EPI formula); diurnal diuresis volume; diurnal urinary excretion of albumin, potassium and sodium; diurnal excretion of metanephrines and normetanephrines; and plasma levels of glucose and glycated hemoglobin, aldosterone, and active renin. Patients were instructed about maintaining compliance with their antihypertensive and hypoglycemic therapy throughout the study.Results At baseline, patients of both groups were comparable by BP and major clinical indexes, except for higher values of nocturnal SBP variability (p&lt;0.05) in patients with rfAH. At 6 months following renal denervation, both groups displayed significant decreases in office and average daily SBP and also in the "load" with increased mean diurnal SBP. However, the decrease in average daily SBP was almost 4 times greater in the rfAH group than in the ucAH group ( -19.9 and -5.1 mm Hg, respectively, р=0.02). Moreover, 81 % of patients in the rfAH group responded to the intervention (average daily SBP decrease ≥10 mm Hg) while the number of responders in the ucAH group was considerably smaller (42 %; p=0.02). In patients with rfAH, renal denervation was associated with a significant decrease in pulse BP and nocturnal SBP variability and with the increase in diurnal diuresis. No other alterations were noted in laboratory test results in either group.Conclusion      DM patients with rfAH may be the best candidates for the procedure of renal denervation.

[Refractory and resistant hypertension in patients with type 2 diabetes mellitus: differences in metabolic profile and endothelial function]

AIM

To determine the prevalence of refractory hypertension (RfH) in patients with and without type 2 diabetes mellitus (DM), as well as to evaluate whether diabetic patients with RfH significant differ from those with uncontrolled resistant hypertension (RH) in clinical phenotype, metabolic profile and endothelial function.

MATERIALS AND METHODS

The study included 193 patients with RH: RH 74 patients with diabetes and 119 patients without DM. Uncontrolled RH and RfH were defined by the presence of uncontrolled blood pressure BP (140 and/or 90 mm Hg) despite the use of 3 but 5 antihypertensive drugs (for RH) and 5 antihypertensive drugs, including a mineralocorticoid receptor antagonist (for RfH). Clinical examination, lab tests were performed. Flow-mediated dilation (FMD) and vasoreactivity of middle cerebral artery (MCA) using both breath-holding and hyperventilation test were measured by high-resolution ultrasound.

RESULTS

The prevalence of refractory hypertension in patients with and without DM was similar (30% vs 28%, respectively). No differences in BP levels, data of echocardiography and clinical phenotype were found between the diabetic groups, but value of HOMA index, plasma resistin level and postprandial glycaemia were higher in patients with RfH. FMD and MCA reactivity to the breath-holding test were worse in patients with RfH, and they had a more pronounced vasoconstrictor response of MCA to the hyperventilation test compared to patients with RH.

CONCLUSION

The prevalence of RfH is the same in patients with and without diabetes. Diabetic patients with refractory hypertension have a more unfavorable metabolic profile and greater impairment of endothelial function than patients with uncontrolled resistant hypertension.

β-Arrestin-Biased Agonist Targeting the Brain AT1R (Angiotensin II Type 1 Receptor) Increases Aversion to Saline and Lowers Blood Pressure in Deoxycorticosterone Acetate-Salt Hypertension

Activation of central AT₁Rs (angiotensin type 1 receptors) is required for the increased blood pressure, polydipsia, and salt intake in deoxycorticosterone acetate (DOCA)-salt hypertension. TRV120027 (TRV027) is an AT₁R-biased agonist that selectively acts through β-arrestin. We hypothesized that intracerebroventricular administration of TRV027 would ameliorate the effects of DOCA-salt. In a neuronal cell line, TRV027 induced AT_1aR internalization through dynamin and clathrin-mediated endocytosis. We next evaluated the effect of chronic intracerebroventricular infusion of TRV027 on fluid intake. We measured the relative intake of water versus various saline solutions using a 2-bottle choice paradigm in mice subjected to DOCA with a concomitant intracerebroventricular infusion of either vehicle, TRV027, or losartan. Sham mice received intracerebroventricular vehicle without DOCA. TRV027 potentiated DOCA-induced water intake in the presence or absence of saline. TRV027 and losartan both increased the aversion for saline-an effect particularly pronounced for highly aversive saline solutions. Intracerebroventricular Ang (angiotensin) II, but not TRV027, increased water and saline intake in the absence of DOCA. In a separate cohort, blood pressure responses to acute intracerebroventricular injection of vehicle, TRV, or losartan were measured by radiotelemetry in mice with established DOCA-salt hypertension. Central administration of intracerebroventricular TRV027 or losartan each caused a significant and similar reduction of blood pressure and heart rate. We conclude that administration of TRV027 a selective β-arrestin biased agonist directly into the brain increases aversion to saline and lowers blood pressure in a model of salt-sensitive hypertension. These data suggest that selective activation of AT₁R β-arrestin pathways may be exploitable therapeutically.

Adverse Health Outcomes Associated With Refractory and Treatment-Resistant Hypertension in the Chronic Renal Insufficiency Cohort

Refractory hypertension (RfH) is a severe phenotype of antihypertension treatment failure. Treatment-resistant hypertension (TRH), a less severe form of difficult-to-treat hypertension, has been associated with significantly worse health outcomes. However, no studies currently show how health outcomes may worsen upon progression to RfH. RfH and TRH were studied in 3147 hypertensive participants in the CRIC (Chronic Renal Insufficiency Cohort study). The hypertensive phenotype (ie, no TRH or RfH, TRH, or RfH) was identified at the baseline visit, and health outcomes were monitored at subsequent visits. Outcome risk was compared using Cox proportional hazards models with time-varying covariates. A total of 136 (4.3%) individuals were identified with RfH at baseline. After adjusting for participant characteristics, individuals with RfH had increased risk for the composite renal outcome across all study years (50% decline in estimated glomerular filtration rate or end-stage renal disease; hazard ratio for study years 0-10=1.73 [95% CI, 1.42-2.11]) and the composite cardiovascular disease outcome during later study years (stroke, myocardial infarction, or congestive heart failure; hazard ratio for study years 0-3=1.25 [0.91-1.73], for study years 3-6=1.50 [0.97-2.32]), and for study years 6-10=2.72 [1.47-5.01]) when compared with individuals with TRH. There was no significant difference in all-cause mortality between those with refractory versus TRH. We provide the first evidence that RfH is associated with worse long-term health outcomes compared with TRH.

Renovascular Hypertension

Renovascular hypertension (RVH) is relatively common but underrecognized cause of resistant hypertension in clinical practice. Most patients with RVH have suboptimal control of hypertension in spite of being on multiple anti hypertensive medications. Prompt diagnosis and management is crucial to prevent long term morbidity and mortality. Initial evaluation by primary care physicians can expedite this to improve patient outcomes by co-managing hypertension specialists. In addition to pharmacologic and nonpharmacologic measures, some patients may benefit from angioplasty. This article discusses various definitions of hypertension, approach to diagnosis of RVH, and management. Data from clinical trials are discussed with evidence-based medicine practice recommendations.

Obstructive sleep apnea is more severe in men but not women with refractory hypertension compared with controlled resistant hypertension

OBJECTIVES

Obstructive sleep apnea (OSA) is associated with treatment-resistant hypertension (RHTN) and may contribute to refractory hypertension (RfHTN). The objective of the current study was to test the hypothesis that patients with RfHTN have more severe OSA compared with patients with controlled RHTN.

METHODS

Patients (n = 187) referred to the University of Alabama at Birmingham Hypertension Clinic for evaluation and treatment of RHTN, defined as uncontrolled blood pressure (BP) (SBP ≥ 130 mmHg or DBP ≥ 80 mmHg) despite the use of at least three antihypertensive medications including a diuretic, were enrolled following completion of at least three follow-up clinic visits. RfHTN was defined as uncontrolled high BP despite treatment with five or more antihypertensive agents of different classes, including a long-acting thiazide-type diuretic and a mineralocorticoid receptor antagonist. Following enrollment, all patients (n = 130) completed 24-h ambulatory BP measurement and overnight diagnostic polysomnography during normal nightly use of continuous positive airway pressure. Analyses examined the severity of OSA and related sleep characteristics among patients with RfHTN versus controlled RHTN.

RESULTS

Of the 130 evaluated patients, 37 (28.5%) had RfHTN and 93 (71.5%) had controlled RHTN. In unadjusted analyses, there was not a significant difference in OSA severity, oxygen saturation, or hypoxemia time in patients with RfHTN versus controlled RHTN (P > 0.05). Men with RfHTN had more severe OSA compared with men with controlled RHTN (P = 0.044). In adjusted analyses, OSA severity was associated with sex (P < 0.0001), but not hypertension phenotype (P = 0.17).

CONCLUSION

The severity of OSA may contribute to RfHTN status in men but not women.

Resistant Hypertension in Chronic Kidney Disease (CKD): Prevalence, Treatment Particularities, and Research Agenda

PURPOSE OF REVIEW

To explore the prevalence, treatment particularities, and research agenda in the management of resistant hypertension among patients with chronic kidney disease (CKD).

RECENT FINDINGS

The prevalence of resistant hypertension is reported to be 2-3 times higher in patients with CKD than in the general hypertensive population. Based in part on the results of the PATHWAY-2 trial showing add-on spironolactone to be superior to placebo or active treatment with an α- or β-blocker in reducing BP, international guidelines recommend the use of spironolactone as fourth-line agent in pharmacotherapy of resistant hypertension. Despite the several-fold higher burden of resistant hypertension among patients with stage 3b-4 CKD, the use of spironolactone in this population has been restricted, mainly due to the risk of hyperkalemia. The recently reported AMBER trial showed that among patients with uncontrolled resistant hypertension and an estimated glomerular filtration rate of 25-45 ml/min/1.73m², the newer potassium-binder patiromer prevented the development of hyperkalemia and increased the proportion of participants who remained on add-on spironolactone over 12 weeks of follow-up. Administration of spironolactone was associated with a clinically meaningful reduction of 11-12 mmHg in unattended automated office systolic blood pressure (BP) over the course of the AMBER trial. Newer potassium-binding therapies overcome the barrier of hyperkalemia and facilitate the persistent use of spironolactone, which is an effective add-on therapy to control BP in patients with resistant hypertension and advanced CKD. Future trials are now warranted to explore whether this strategy confers benefits on "hard" clinical outcomes in this high-risk population.

Prevalence and clinical profile of refractory hypertension in a large cohort of patients with resistant hypertension

Refractory hypertension (RfHT) is an extreme phenotype of resistant hypertension (RHT) and is considered uncontrolled blood pressure (BP) despite the use of five or more antihypertensives. The objective of this study was to characterize the prevalence and clinical profile of RfHT patients in a historical cohort of patients with RHT at two different times: before and after the introduction of spironolactone. First, this cross-sectional study evaluated 1048 RHT patients (72.3% females, mean [SD] age: 61.2 [11.3] years) referred to a hypertension clinic (prespironolactone period). All patients were submitted to a standard protocol including clinical and complementary exams. Second, the analysis evaluated patients after the introduction of spironolactone (postspironolactone period). Statistical analysis included bivariate comparisons between patients with RHT and patients with RfHT and logistic regressions to assess the independent correlations of RfHT. A total of 146 patients (13.9%) remained refractory despite the use of at least five antihypertensives (prespironolactone period). After the introduction of spironolactone, the prevalence increased to 17.6%. For any criterion, RfHT patients were younger and more obese. In the initial period, current smoking and left ventricular hypertrophy were independently correlated with RfHT. Furthermore, after spironolactone use, RfHT patients had lower aortic stiffness and peripheral artery disease (PAD), pointing to a lower cardiovascular risk despite the lack of BP control. Younger age and lower prevalence of PAD correlated independently with RfHT. In conclusion, there was a high prevalence of RfHT, especially in younger and obese patients, and spironolactone use seemed to reduce cardiovascular risk despite the lack of BP control.

Refractory Hypertension and Risks of Adverse Cardiovascular Events and Mortality in Patients With Resistant Hypertension: A Prospective Cohort Study

Background

The long‐term prognosis of refractory hypertension (RfHT), defined as failure to control blood pressure (BP) levels despite an antihypertensive treatment with ≥5 medications including a diuretic and mineraloreceptor antagonist, has never been evaluated.

Methods and Results

In a prospective cohort study with 1576 patients with resistant hypertension, patients were classified as refractory or nonrefractory based on uncontrolled clinic (or office) and ambulatory BPs during the first 2 years of follow‐up. Multivariate Cox analyses examined the associations between the diagnosis of RfHT and the occurrence of total cardiovascular events (CVEs), major adverse CVEs, and cardiovascular and all‐cause mortality, after adjustments for other risk factors. In total, 135 patients (8.6%) had RfHT by uncontrolled ambulatory BPs and 167 (10.6%) by uncontrolled clinic BPs. Over a median Follow‐Up of 8.9 years, 338 total CVEs occurred (288 major adverse CVEs, including 124 myocardial infarctions, and 96 strokes), and 331 patients died, 196 from cardiovascular causes. The diagnosis of RfHT, using either classification by clinic or ambulatory BPs, was associated with significantly higher risks of major adverse CVEs, cardiovascular mortality, and stroke incidence, with hazard ratios varying from 1.54 to 2.14 in relation to patients with resistant nonrefractory hypertension; however, the classification based on ambulatory BPs was better in identifying higher risk patients than the classification based on clinic BP levels.

Conclusions

Patients with RfHT, particularly when defined by uncontrolled ambulatory BP levels, had higher risks of major adverse CVEs and mortality in relation to patients with resistant but nonrefractory hypertension, supporting the concept of refractory hypertension as a true extreme phenotype of antihypertensive treatment failure.

Reserpine Substantially Lowers Blood Pressure in Patients With Refractory Hypertension: A Proof-of-Concept Study

BACKGROUND

Refractory hypertension (RfHTN), a phenotype of antihypertensive treatment failure, is defined as uncontrolled automated office blood pressure (AOBP) ≥130/80 mm Hg and awake ambulatory blood pressure (ABP) ≥130/80 mm Hg on ≥5 antihypertensive medications, including chlorthalidone and a mineralocorticoid receptor antagonist. Previous studies suggest that RfHTN is attributable to heightened sympathetic tone. The current study tested whether reserpine, a potent sympatholytic agent, lowers blood pressure (BP) in patients with RfHTN.

METHODS

Twenty-one out of 45 consecutive patients with suspected RfHTN were determined to be fully adherent with their antihypertensive regimen. Seven patients agreed to participate in the current clinical trial with reserpine and 6 patients completed the study. Other sympatholytic medications, such as clonidine or guanfacine, were tapered and discontinued before starting reserpine. Reserpine 0.1 mg daily was administered in an open-label fashion for 4 weeks. All patients were evaluated by AOBP and 24-hour ABP at baseline and after 4 weeks of treatment.

RESULTS

Reserpine lowered mean systolic and diastolic AOBP by 29.3 ± 22.2 and 22.0 ± 15.8 mm Hg, respectively. Mean 24-hour systolic and diastolic ABPs were reduced by 21.8 ± 13.4 and 15.3 ± 9.6 mm Hg, mean awake systolic and diastolic ABPs by 23.8 ± 11.8 and 17.8 ± 9.2 mm Hg, and mean asleep systolic and diastolic ABPs by 21.5 ± 11.4 and 13.7 ± 6.4 mm Hg, respectively.

CONCLUSIONS

Reserpine, a potent sympatholytic agent, lowers BP in patients whose BP remained uncontrolled on maximal antihypertensive therapy, lending support to the hypothesis that excess sympathetic output contributes importantly to the development of RfHTN.

Clinical Characteristics of Resistant vs. Refractory Hypertension in a Population of Hypertensive Afrodescendants

Background Afrodescendants have been associated with a greater severity of arterial hypertension and a higher incidence of cardiovascular complications. Characteristics in the presentation of resistant hypertension (RH) or refractory hypertension (RfH), specifically in this ethnic group, have not been properly studied. Objectives The study compares clinical and epidemiological characteristics and prevalence of cardiovascular events in people of African descent diagnosed with RH or RfH. Methods Cross-sectional study carried out in a referral clinic for patients with severe hypertension. The level of significance was 5%. Results 146 consecutive patients were evaluated, of which 68.7% were female. The average age was 61.8 years, with 88.4% of Afrodescendants (mixed race or black). 51% had RfH. There was a high prevalence of cardiovascular risk factors: 34.2% of subjects had diabetes, 69.4% dyslipidemia, 36.1% obesity, and 38.3% history of smoking. Reduced renal function was seen in 34.2%. Previous cardiovascular events occurred in 21.8% for myocardial infarction and in 19.9% for stroke. The Framingham's risk score was moderate/high at 61%. RfH patients were younger (mean age 59.38±11.69 years versus 64.10±12.23 years, p=0.02), had more dyslipidemia (83.8 versus 66.7%, p=0.021), and stroke (30.4 versus 12.3%, p=0.011) when compared to those with RH. The use of a combination of ACEi/ARB+CCB+Diuretic, chlortalidone and spironolactone was also more frequent in individuals with RfH. Conclusion Africandescendant people with RH had a high cardiovascular risk, a high prevalence of RfH, a higher frequency of dyslipidemia and stroke, compatible with a high incidence of injury to target organs. (Arq Bras Cardiol.2020; 115(1):31-39).

Frequency and factors linked to refractory hypertension among stroke survivors in Ghana

BACKGROUND

Refractory hypertension (RfH) is a rare, severe phenotype of resistant hypertension, linked to higher risk of adverse cardiovascular outcomes. Little is known about the association of RfH with stroke type and subtype.

OBJECTIVE

To determine the prevalence and predictors of RfH among stroke survivors in Ghana.

METHODS

We interrogated the dataset of a prospectively collected registry of hypertensive patients seen between July 2015 and June 2019, at five hospitals in Ghana. We compared stroke survivors to stroke-free controls. Clinic-based blood pressure was measured using a standardized protocol and antihypertensive medications were assessed via review of medical records and inspection of pills. Refractory hypertension was defined as office BP ≥140/90 mmHg on ≥5 classes of antihypertensive medications. Multivariate logistic regression models were constructed to assess factors associated with RfH.

RESULTS

Of 3927 hypertensive patients (1169 stroke survivors, 2758 controls), 86 had RfH for an overall prevalence of 2.2% (95% CI: 1.8-2.7%). Among patients with RfH, 5.8% (4.5-7.3%) were stroke survivors vs. 0.7% (0.4-1.0%) were stroke-free (p < .0001). Adjusted odds ratio (95% CI) for factors associated with RfH were being male (1.81, 1.15-2.85), age < 60 years (2.64, 1.59-4.40), chronic kidney disease (2.09, 1.21-3.60), and known stroke (7.53, 4.35-13.04). RfH was associated with intracerebral hemorrhage, (11.43, 5.65-23.14), ischemic stroke (9.76, 5.47-17.42), lacunar stroke (13.58, 6.45-28.61), and non-lacunar ischemic stroke (3.67, 1.04-13.02).

CONCLUSION

Presence of RfH is significantly accentuated among stroke survivors. Intensified efforts are warranted to identify and aggressively address barriers to control in these patients to avert subsequent vascular events.

Association of the genetic ancestry with resistant hypertension in the ReHOT (Resistant Hypertension Optimal Treatment) randomized study

Resistant hypertension (RH) is defined as uncontrolled blood pressure despite treatment with three or more antihypertensive medications, including, if tolerated, a diuretic in adequate doses. It has been widely known that race is associated with blood pressure control. However, intense debate persists as to whether this is solely explained by unadjusted socioeconomical variables or genetic variation. In this scenario, the main aim was to evaluate the association between genetic ancestry and resistant hypertension in a large sample from a multicenter trial of stage II hypertension, the ReHOT study. Samples from 1,358 patients were analyzed, of which 167 were defined as resistant hypertensive. Genetic ancestry was defined using a panel of 192 polymorphic markers. The genetic ancestry was similar in resistant (52.0% European, 36.7% African and 11.3% Amerindian) and nonresistant hypertensive patients (54.0% European, 34.4% African and 11.6% Amerindian) (p > 0.05). However, we observed a statistically suggestive association of African ancestry with resistant hypertension in brown patient group. In conclusion, increased African genetic ancestry was not associated with RH in Brazilian patients from a prospective randomized hypertension clinical trial.

Treatment of Resistant and Refractory Hypertension

Resistant hypertension (RHTN) is defined as uncontrolled blood pressure despite the use of ≥3 antihypertensive agents of different classes, including a diuretic, usually thiazide-like, a long-acting calcium channel blocker, and a blocker of the renin- angiotensin system, either an ACE (angiotensin-converting enzyme) inhibitor or an ARB (angiotensin receptor blocker), at maximal or maximally tolerated doses. Antihypertensive medication nonadherence and the white coat effect, defined as elevated blood pressure when measured in clinic but controlled when measured outside of clinic, must be excluded to make the diagnosis. RHTN is a high-risk phenotype, leading to increased all-cause mortality and cardiovascular disease outcomes. Healthy lifestyle habits are associated with reduced cardiovascular risk in patients with RHTN. Aldosterone excess is common in patients with RHTN, and addition of spironolactone or amiloride to the standard 3-drug antihypertensive regimen is effective at getting the blood pressure to goal in most of these patients. Refractory hypertension is defined as uncontrolled blood pressure despite use of ≥5 antihypertensive agents of different classes, including a long-acting thiazide-like diuretic and an MR (mineralocorticoid receptor) antagonist, at maximal or maximally tolerated doses. Fluid retention, mediated largely by aldosterone excess, is the predominant mechanism underlying RHTN, while patients with refractory hypertension typically exhibit increased sympathetic nervous system activity.

Obstructive sleep apnea, hypertension, resistant hypertension and cardiovascular disease

Obstructive sleep apnea (OSA) is one of the most common causes of hypertension (HTN) and cardiovascular disease (CVD). It is also a quite common underlying factor in resistant HTN (RHTN). The main etiological factor of OSA is obesity, which is a rapidly growing global epidemic. To control obesity, patients should be encouraged by health care professionals to lose weight and be educated about weight loss strategies such as lifestyle modifications, which include regular exercise, low-calorie diet, low sodium intake, smoking cessation, and decreased alcohol consumption. This review also emphasizes the importance of screening for OSA as the major underlying cause of essential, and RHTN, which can lead to CVD and can cause end-organ damage. It also stresses the importance of using continuous positive airway pressure (CPAP) and its beneficial effects, along with other antihypertensive regimens, in treating HTN, and RHTN. Treatment with CPAP therapy decreases sympathetic activity, high blood pressure (BP), heart rate, and CVD as well as its associated mortality.

Resistant hypertension-defining the scope of the problem

The updated scientific statement by the American Heart Association has defined resistant hypertension (HTN;RH) as uncontrolled blood pressure (BP) ≥ 130/80 mmHg, despite concurrent use of 3 anti-HTN drug classes comprising a calcium channel blocker, a blocker of renin-angiotensin system, and a thiazide diuretic, preferably chlorthalidone. Using the updated BP criteria, the prevalence of RH in the United States is found to be modestly increased by approximately 3-4% among treated population. Meta-analysis of observational studies have demonstrated that pseudo-RH from white coat HTN or medication nonadherence is as much common as the truly RH. Thus, screening for pseudo-resistance in the evaluation of all apparent RH is of utmost importance as diagnosis of white-coat HTN requires no treatment, while medication nonadherence would benefit from identifying and targeting barriers to adherence.

Antihypertensive Medication Adherence and Confirmation of True Refractory Hypertension

Refractory hypertension (RfHTN) is a phenotype of antihypertensive treatment failure defined as uncontrolled BP despite the use of effective doses of ≥5 antihypertensive medications including a long-acting thiazide-like diuretic (chlorthalidone) and a mineralocorticoid receptor antagonist. The degree of medication nonadherence is unknown among patients with RfHTN. In this prospective evaluation, 54 patients with apparent RfHTN were recruited from the University of Alabama at Birmingham Hypertension Clinic after having uncontrolled BP at 3 or more clinic visits. All patients' BP was evaluated by automated office BP and 24-hour ambulatory BP monitoring (n=49). Antihypertensive medication adherence was determined by measuring 24-hour urine specimens for antihypertensive medications and their metabolites by high-performance liquid chromatography-tandem mass spectrometry (n=45). Of the 45 patients who completed 24-hour ambulatory BP monitoring, 40 (88.9%) had confirmed RfHTN based on an elevated automated office BP (≥130/80 mm Hg), mean 24-hour ABP (≥125/75 mm Hg), and mean awake (day-time) ABP (≥130/80 mm Hg). Out of the 40 fully evaluated patients with RfHTN, 16 (40.0%) were fully adherent with all prescribed medications. Eighteen (45.0%) patients were partially adherent and 6 (15.0%) had none of the prescribed agents detected in their urine. Of 18 patients who were partially adherent, 5 (12.5%) were adherent with at least 5 medications, including chlorthalidone and the mineralocorticoid receptor antagonist, consistent with true RfHTN. Of patients identified as having apparent RfHTN, 52.5% were adherent with at least 5 antihypertensive medications, including chlorthalidone and a mineralocorticoid receptor antagonist, confirming true RfTHN. These findings validate RfHTN as a rare, but true phenotype of antihypertensive treatment failure.

Resistant Hypertension: A Clinical Perspective

Resistant hypertension is a common clinical entity, defined as suboptimal blood pressure response to multiple therapies after excluding medication nonadherence and secondary forms of hypertension. Patients with resistant hypertension generally share several comorbidities. Resistant hypertension is more common in individuals of African descent. Blood pressure should be optimized using multiple strategies, including lifestyle changes and single-pill combination therapies, with the aim of reducing cardiovascular events while reducing side effects from using antihypertensive therapy. A renin/aldosterone-based diagnostic and treatment approach will help tailor therapy. The use of mineralocorticoid receptor antagonists or amiloride as appropriate is favored.

Resistant/Refractory Hypertension and Sleep Apnoea: Current Knowledge and Future Challenges

Hypertension is one of the most frequent cardiovascular risk factors. The population of hypertensive patients includes some phenotypes whose blood pressure levels are particularly difficult to control, thus putting them at greater cardiovascular risk. This is especially true of so-called resistant hypertension (RH) and refractory hypertension (RfH). Recent findings suggest that the former may be due to an alteration in the renin-angiotensin-aldosterone axis, while the latter seems to be more closely related to sympathetic hyper-activation. Both these pathophysiological mechanisms are also activated in patients with obstructive sleep apnoea (OSA). It is not surprising, therefore, that the prevalence of OSA in RH and RfH patients is very high (as reflected in several studies) and that treatment with continuous positive airway pressure (CPAP) manages to reduce blood pressure levels in a clinically significant way in both these groups of hypertensive patients. It is therefore necessary to incorporate into the multidimensional treatment of patients with RH and RfH (changes in lifestyle, control of obesity and drug treatment) a study of the possible existence of OSA, as this is a potentially treatable disease. There are many questions that remain to be answered, especially regarding the ideal combination of treatment in patients with RH/RfH and OSA (drugs, renal denervation, CPAP treatment) and patients' varying response to CPAP treatment.

Resistant Hypertension: Novel Insights

Hypertension is the most common chronic disease and the leading risk factor for disability and premature deaths in the world, accounting for more than 9 million deaths annually. Resistant hypertension is a particularly severe form of hypertension. It was described 50 years ago and since then has been a very active field of research. This review aims at summarizing the most recent findings on resistant hypertension. The recent concepts of apparent- and true-resistant hypertension have stimulated a more precise definition of resistant hypertension taking into account not only the accuracy of blood pressure measurement and pharmacological class of prescribed drugs but also patient adherence to drugs and life-style recommendations. Recent epidemiological studies have reported a 10% prevalence of resistant hypertension among hypertensive subjects and demonstrated the high cardiovascular risk of these patients. In addition, these studies identified subgroups of patients with even higher morbidity and mortality risk, probably requiring a more aggressive medical management. In the meantime, guidelines provided more standardized clinical work-up to identify potentially reversible causes for resistant hypertension such as secondary hypertension. The debate is however still ongoing on which would be the optimal method(s) to screen for non-adherence to hypertension therapy, recognized as the major cause for (pseudo)-resistance to treatment. Recent randomized clinical trials have demonstrated the strong benefit of anti-aldosterone drugs (mostly spironolocatone) as fourth-line therapies in resistant hypertension whereas clinical trials with device-based therapies displayed contrasting results. New trials with improved devices and more carefully selected patients with resistant hypertension are ongoing.

Resistant Hypertension Updated Guidelines

PURPOSE OF REVIEW

To discuss the current definition as well as recommendations for diagnosis and treatment of resistant hypertension (RH) based on the 2018 American Heart Association (AHA) guidelines and recent literature.

RECENT FINDINGS

RH is defined as uncontrolled blood pressure (BP) on ≥ 3 anti-hypertensives, one of which should be a diuretic, prescribed at maximally tolerated doses and appropriate dosing frequency. The diagnosis of RH requires exclusion of white coat effect and medication non-adherence, underscoring the importance of out-of-office BP measurements. Secondary causes of hypertension must be excluded in all patients with RH. A step-wise approach to treatment focusing on lifestyle modifications and medication optimization can be effective in > 50% of the patients with RH. Device-based interventional therapies for RH are currently investigational. Out-of-office BP measurements are central to the diagnosis of RH. Medication optimization is successful in most patients. Further studies are needed to define the role of device-based interventions.

Conditional deletion of smooth muscle Cullin-3 causes severe progressive hypertension

Patients with mutations in Cullin-3 (CUL3) exhibit severe early onset hypertension but the contribution of the smooth muscle remains unclear. Conditional genetic ablation of CUL3 in vascular smooth muscle (S-CUL3KO) causes progressive impairment in responsiveness to nitric oxide (NO), rapid development of severe hypertension, and increased arterial stiffness. Loss of CUL3 in primary aortic smooth muscle cells or aorta resulted in decreased expression of the NO receptor, soluble guanylate cyclase (sGC), causing a marked reduction in cGMP production and impaired vasodilation to cGMP analogues. Vasodilation responses to a selective large conductance Ca2+-activated K+-channel activator were normal suggesting that downstream signals which promote smooth muscle-dependent relaxation remained intact. We conclude that smooth muscle specific CUL3 ablation impairs both cGMP production and cGMP responses and that loss of CUL3 function selectively in smooth muscle is sufficient to cause severe hypertension by interfering with the NO-sGC-cGMP pathway. Our study provides compelling evidence for the sufficiency of vascular smooth muscle CUL3 as a major regulator of BP. CUL3 mutations cause severe vascular dysfunction, arterial stiffness and hypertension due to defects in vascular smooth muscle.

The Potential Role of Obstructive Sleep Apnoea in Refractory Hypertension

PURPOSE OF REVIEW

This review seeks to present an overview of the recently found association between refractory hypertension (RfH) and obstructive sleep apnoea (OSA).

RECENT FINDINGS

RfH was recently defined as an extreme phenotype of resistant hypertension characterized by the lack of blood pressure control despite using ≥ 5 antihypertensive drugs at optimal doses. Current data support that the pathophysiological pathway of both types of hypertension is different. The main mechanism involved in resistant hypertension is fluid retention whereas in the case of RfH is the sympathetic over-activity. OSA is now recognized as a cause of hypertension (especially in the case of difficult-to-treat hypertension). It seems that the biological mechanism linking OSA and arterial hypertension is the sympathetic over-activity related to the respiratory events (apnoeas and hypopnoeas) during the night. So, it is not surprising that, although the literature is scarce, some studies have found a very high prevalence of OSA and an excess of sympathetic activity in patients with RfH. Finally, a very recent study demonstrated that continuous positive airway pressure (CPAP) treatment, which controls sympathetic activation in OSA patients, achieves very significant reductions in blood pressure levels in RfH patients, even greater than in those with resistant (non-refractory) hypertension. The prevalence of OSA in patients with RfH is very high. CPAP treatment achieves a clinically significant reduction in blood pressure levels in those patients with RfH (especially in night readings). Patients with RfH must be sent to a sleep unit for a study.

Beyond Resistant Hypertension

Obstructive sleep apnea (OSA) is an independent cause of resistant hypertension (RH) but its association with refractory hypertension (RfH), a recently described form of severe hypertension, has not yet been investigated. This study seeks to analyze the association between the presence and severity of OSA/OSA syndrome with RfH and to compare it with a group of patients with OSA/OSA syndrome and RH. We conducted a multicenter, cross-sectional study of consecutive patients diagnosed with RH by means of 24-hour ambulatory blood pressure monitoring. Those patients with blood pressure levels ≥130/80 mm Hg, despite taking at least 5 antihypertensive drugs, were considered to have true RfH. All patients underwent a sleep study and completed a detailed clinical history related to OSA, current medication, and cardiovascular diseases. Overall, 229 patients were included (mean age, 58.3 years; 63% male), of whom 42 (18.3%) satisfied the criteria for RfH. Compared with those with RH, patients with RfH had a higher cardiovascular risk profile, higher blood pressure measurements, and a 2-fold greater risk of having both severe OSA (odds ratio, 2.1, with a prevalence of apnea-hypopnea index ≥15, 95.2% and apnea-hypopnea index ≥30, 64.3%) and OSA syndrome (apnea-hypopnea index ≥5+Epworth Sleepiness Scale >10; odds ratio, 1.9; 52.4% versus 37.3%; P=0.023), as well as higher OSA severity (apnea-hypopnea index, 41.8 versus 33.8 events/h; P=0.026). Patients with RfH had an even greater prevalence and severity of OSA and OSA syndrome than RH patients, highlighting the need to identify these patients to refer them to sleep units on a preferential basis.