Refractory Hypertension Is not Attributable to Intravascular Fluid Retention as Determined by Intracardiac Volumes

Opportunities and Limitations of Renal Denervation: Where Do We Stand?

Hypertension is a primary contributor to cardiovascular disease, and the leading risk factor for loss of quality adjusted life years. Up to 50% of the cases of hypertension in the United States remain uncontrolled. Additionally, 8%-18% of the hypertensive population have resistant hypertension; uncontrolled pressure despite 3 different antihypertensive agents. Recently, catheter-based percutaneous renal denervation emerged as a method for ablating renal sympathetic nerves for difficult-to-control hypertension. Initial randomized (non-sham) trials and registry analyses showed impressive benefit, but the first sham-controlled randomized controlled trial using monopolar radiofrequency ablation showed limited benefit. With refinement of techniques to include multipolar radiofrequency, ultrasound denervation, and direct ethanol injection, randomized controlled trials demonstrated significant blood pressure improvement, leading to US Food and Drug Administration approval of radiofrequency- and ultrasound-based denervation technologies. In this review article, we summarize the major randomized sham-controlled trials and societal guidelines regarding the efficacy and safety of renal artery denervation for the treatment of uncontrolled hypertension.

The Global Burden of Resistant Hypertension and Potential Treatment Options

Resistant hypertension (RH) is defined as systolic blood pressure (SBP) or diastolic blood pressure (DBP) that remains .140 mmHg or .90 mmHg, respectively, despite an appropriate lifestyle and the use of optimal or maximally tolerated doses of a three-drug combination, including a diuretic. This definition encompasses the category of controlled RH, defined as the presence of blood pressure (BP) effectively controlled by four or more antihypertensive agents, as well as refractory hypertension, referred to as uncontrolled BP despite five or more drugs of different classes, including a diuretic. To confirm RH presence, various causes of pseudo-resistant hypertension (such as improper BP measurement techniques and poor medication adherence) and secondary hypertension must be ruled out. Inadequate BP control should be confirmed by out-of-office BP measurement. RH affects about 5% of the hypertensive population and is associated with increased cardiovascular morbidity and mortality. Once RH presence is confirmed, patient evaluation includes identification of contributing factors such as lifestyle issues or interfering drugs/substances and assessment of hypertension-mediated organ damage. Management of RH comprises lifestyle interventions and optimisation of current medication therapy. Additional drugs should be introduced sequentially if BP remains uncontrolled and renal denervation can be considered as an additional treatment option. However, achieving optimal BP control remains challenging in this setting. This review aims to provide an overview of RH, including its epidemiology, pathophysiology, diagnostic work-up, as well as the latest therapeutic developments.

Controversies in Hypertension V: Resistant and Refractory Hypertension

Apparent resistant hypertension, defined as uncontrolled office blood pressure despite ≥ 3 antihypertensive medications including a diuretic or use of ≥ 4 medications regardless of blood pressure, occurs in ≤ 15% of treated hypertensives. Apparent refractory hypertension, defined as uncontrolled office pressure despite use of 5 or more medications including a diuretic, occurs in ≤ 10% of resistant cases. Both are associated with increased comorbidity and enhanced cardiovascular risk. To rule out pseudo-resistant or pseudo-refractory hypertension, employ guideline-based methodology for obtaining pressure, maximize the regimen, rule out white-coat effect, and assess adherence. True resistant hypertension is characterized by volume overload and aldosterone excess, refractory by enhanced sympathetic tone. Spironolactone is the preferred agent for resistance, with lower doses. Spironolactone, potassium binders, or both, are preferred if the estimated glomerular filtration rate is below 45. If significant albuminuria, finerenone is indicated. The optimal treatment of refractory hypertension is unclear, but sympathetic inhibition (α-β blockade, centrally acting sympathoinhibitors, or both) seems reasonable. Renal denervation has shown minimal benefit for resistance, but its role in refractory hypertension remains to be defined.

Resistant hypertension: consensus document from the Korean society of hypertension

Although reports vary, the prevalence of true resistant hypertension and apparent treatment-resistant hypertension (aTRH) has been reported to be 10.3% and 14.7%, respectively. As there is a rapid increase in the prevalence of obesity, chronic kidney disease, and diabetes mellitus, factors that are associated with resistant hypertension, the prevalence of resistant hypertension is expected to rise as well. Frequently, patients with aTRH have pseudoresistant hypertension [aTRH due to white-coat uncontrolled hypertension (WUCH), drug underdosing, poor adherence, and inaccurate office blood pressure (BP) measurements]. As the prevalence of WUCH is high among patients with aTRH, the use of out-of-office BP measurements, both ambulatory blood pressure monitoring (ABPM) and home blood pressure monitoring (HBPM), is essential to exclude WUCH. Non-adherence is especially problematic, and methods to assess adherence remain limited and often not clinically feasible. Therefore, the use of HBPM and higher utilization of single-pill fixed-dose combination treatments should be emphasized to improve drug adherence. In addition, primary aldosteronism and symptomatic obstructive sleep apnea are quite common in patients with hypertension and more so in patients with resistant hypertension. Screening for these diseases is essential, as the treatment of these secondary causes may help control BP in patients who are otherwise difficult to treat. Finally, a proper drug regimen combined with lifestyle modifications is essential to control BP in these patients.

Refractory Arterial Hypertension: Features of Neurohormonal and Water-salt Imbalanceand Approaches to Antihypertensive Drug Therapy

Refractory arterial hypertension is characterized by a lack of control of target blood pressure, despite the prolonged use >5 antihypertensive drugs with different mechanisms of action, including longacting diuretic chlorthalidone and the mineralcorticoid receptor antagonists (spironolactone or eplerenone). The review presents the results of clinical studies devoted the elucidating peculiarities of the neurohormonal status and water-salt balance in such patients and developing new approaches to antihypertensive drug therapy based on them. According to these studies, individuals with refractory hypertension differ from patients with resistant hypertension with the higher of sympathetic nervous system activity and the absence of an increased of intrathoracic fluid volume, which indirectly indicates a significant decrease in the intravascular fluid volume. In this regard, the review focuses on the data obtained in assessing the clinical efficacy of sympatholytics clonidine and reserpine in patients with resistant and refractory hypertension, as well as renal sodium-glucose co-transporter type 2 inhibitors, which suppress the sympathetic nervous system activity and can be used to overcome refractory hypertension in patients with type 2 diabetes.

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.

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<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.

Resistant hypertension: new insights and therapeutic perspectives

Resistant hypertension (RH) is a concept that currently goes beyond the classical definition of blood pressure ≥140/90 mmHg in subjects receiving three or more drugs of different classes at maximally tolerated doses. Here, we review the clinical relevance of RH and the different types of RH-associated phenotypes, namely refractory hypertension, controlled resistant hypertension, and masked uncontrolled hypertension. We also discuss current drug strategies and future treatments for these high-risk phenotypes.

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.

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.

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.

Recent advances in understanding and managing resistant/refractory hypertension

The management of resistant hypertension presents several challenges in everyday clinical practice. During the past few years, several studies have been performed to identify efficient and safe pharmacological and non-pharmacological options for the management of such patients. The Spironolactone versus placebo, bisoprolol, and doxazosin to determine the optimal treatment for drug-resistant hypertension (PATHWAY-2) trial demonstrated significant benefits with the use of spinorolactone as a fourth-line drug for the treatment of resistant hypertension over doxazosin and bisoprolol. In addition, recent data support that spironolactone may demonstrate superiority over central acting drugs in such patients, as well. Based on the European guidelines, spironolactone is recommended as the fourth-line drug option, followed by amiloride, other diuretics, doxazosin, bisoprolol or clonidine.  Among several device-based approaches, renal sympathetic denervation had fallen into hibernation after the disappointing results of the Renal Denervation in Patients With Uncontrolled Hypertension (SYMPLICITY HTN) 3 trial. However, the technique re-emerged at the epicenter of the clinical and research interest after the favorable results of three sham-controlled studies, which facilitated novel catheters and techniques to perform the denervation. Significant results of iliac anastomosis on blood pressure levels have also been demonstrated. Nevertheless, the technique-related adverse events resulted in withdrawal of this interventional approach. Last, the sympatholytic properties of the carotid baroreceptor activation therapy were associated with significant blood pressure reductions in patients with resistant hypertension, which need to be verified in larger controlled trials. Currently device-based approaches are recommended only in the setting of clinical trials until more safety and efficacy data become available.

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.

Uncontrolled Arterial Hypertension: Kidney, Neurohormonal Imbalance, and Approaches to Antihypertensive Drug Therapy

Resistant and refractory arterial hypertensions are two distinct clinical phenotypes of uncontrolled arterial hypertension (AH), which differ in their sensitivity to antihypertensive drug therapy. The review presents data obtained in clinical studies devoted to elucidating the involvement of disorders of neurohormonal status and renal function in the formation of resistant and refractory arterial hypertension, to and the development of new approaches to increasing the effectiveness of antihypertensive therapy in these patient’s populations. The results of these studies have shown that in patients with uncontrolled arterial hypertension, despite prolonged intake ≥ 3 antihypertensive drugs with different mechanisms of action, including a diuretic, excess sodium reabsorption persists in the distal segments of nephron due to increased aldosterone activity and sympathetic nervous system hyperactivity. In this regard, special attention has been paid to the data of PATHWAY-2, PATHWAY-3 and ReHOT trials that in patients with resistant AH tested the clinical efficacy of spironolactone, amiloride, and antiadrenergic drugs bisoprolol, doxazosin and clonidine, suppressing activity of the sympathetic nervous system.

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 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.