Prevalence of resistant hypertension in the United States, 2003-2008

Profile of ambulatory blood pressure in resistant hypertension

Resistant hypertension (HT) is a condition that confers a high cardiovascular risk to the patient due to both persistent blood pressure elevation and the high prevalence of comorbidities and organ damage. Ambulatory blood pressure monitoring (ABPM) has become an important tool in the diagnosis and follow-up of the hypertensive patient, and it is even more important in the evaluation of those with resistant HT. Data from the Spanish ABPM Registry have allowed the comparison between large groups of resistant hypertensive patients seen in daily life and those controlled on antihypertensive treatment, as well as in resistant hypertensive patients who are classified based on ambulatory blood pressure values. In comparison with controlled patients, the cohort of resistant hypertensives has a worse circadian profile with a high proportion of nondipping, but also stark differences between office and ambulatory blood pressures. This enhanced white-coat effect was responsible for more than one-third of resistant hypertensive patients having normal 24-h blood pressures. Clinical data, including comorbidities, organ damage and circadian patterns, suggest a lower cardiovascular risk among white-coat resistant hypertensives. This finding was in agreement with longitudinal studies in smaller cohorts, suggesting fewer cardiovascular events and less mortality. In summary, it seems reasonable to routinely use ABPM in the initial evaluation of all resistant hypertensive patients. In a significant number of these patients, ABPM will also be an essential tool in follow-up, especially regarding the possible effects of all therapeutic maneuvers that are devoted to bringing blood pressure into target ranges.

Renal sympathetic denervation for treatment of drug-resistant hypertension: one-year results from the Symplicity HTN-2 randomized, controlled trial

BACKGROUND

Renal sympathetic nerve activation contributes to the pathogenesis of hypertension. Symplicity HTN-2, a multicenter, randomized trial, demonstrated that catheter-based renal denervation produced significant blood pressure lowering in treatment-resistant patients at 6 months after the procedure compared with control, medication-only patients. Longer-term follow-up, including 6-month crossover results, is now presented.

METHODS AND RESULTS

Eligible patients were on ≥3 antihypertensive drugs and had a baseline systolic blood pressure ≥160 mm Hg (≥150 mm Hg for type 2 diabetics). After the 6-month primary end point was met, renal denervation in control patients was permitted. One-year results on patients randomized to immediate renal denervation (n=47) and 6-month postprocedure results for crossover patients are presented. At 12 months after the procedure, the mean fall in office systolic blood pressure in the initial renal denervation group (-28.1 mm Hg; 95% confidence interval, -35.4 to -20.7; P<0.001) was similar to the 6-month fall (-31.7 mm Hg; 95% confidence interval, -38.3 to -25.0; P=0.16 versus 6-month change). The mean systolic blood pressure of the crossover group 6 months after the procedure was significantly lowered (from 190.0±19.6 to 166.3±24.7 mm Hg; change, -23.7±27.5; P<0.001). In the crossover group, there was 1 renal artery dissection during guide catheter insertion, before denervation, corrected by renal artery stenting, and 1 hypotensive episode, which resolved with medication adjustment.

CONCLUSIONS

Control patients who crossed over to renal denervation with the Symplicity system had a significant drop in blood pressure similar to that observed in patients receiving immediate denervation. Renal denervation provides safe and sustained reduction of blood pressure to 1 year.

How can resistant hypertension be identified and prevented?

Resistant hypertension is highly prevalent, and is the form of arterial hypertension that is most difficult to treat. Many patients diagnosed with this disease do not have resistant hypertension, but rather have mismanaged primary hypertension. In many cases blood pressure can be controlled by directly addressing underlying causes such as primary aldosteronism, obstructive sleep apnoea, or excessive neurogenic stimulation. Clinicians should ensure that appropriate blood-pressure measurements are used to diagnose resistant hypertension, explore a variety of drug combinations, and battle clinical inertia. Patients should comply with medication schedules and dietary modifications. Correction of these factors will greatly diminish the prevalence of 'resistant' hypertension and avoid the consequences of a persistently elevated blood pressure in these patients.

The worldwide environment of cardiovascular disease: prevalence, diagnosis, therapy, and policy issues: a report from the American College of Cardiology

The environment in which the field of cardiology finds itself has been rapidly changing. This supplement, an expansion of a report created for the Board of Trustees, is intended to provide a timely snapshot of the socio-economic, political, and scientific aspects of this environment as it applies to practice both in the United States and internationally. This publication should assist healthcare professionals looking for the most recent statistics on cardiovascular disease and the risk factors that contribute to it, drug and device trends affecting the industry, and how the practice of cardiology is changing in the United States.

Prevalence of resistant hypertension in 1810 patients followed up in a specialized outpatient clinic and its association with the metabolic syndrome

We aimed to assess the prevalence of resistant hypertension (RH) in patients attending hypertension outpatient clinics and to identify risk factors for RH. We studied the medical records of the last visit of all patients (n = 1810; 40.4% males, age 56.5 ± 13.5 years) who attended at least once our hypertension outpatient clinic during the last decade. RH was defined as blood pressure (BP) > 140/90 mmHg in patients without diabetes or chronic kidney disease (or BP > 130/80 mmHg in patients with the latter diseases) despite treatment with full doses of three antihypertensive agents from different classes or controlled BP on four or more different antihypertensive agents. The prevalence of RH was 12.3%, whereas 22.2% of the patients had well-controlled hypertension and 65.5% had uncontrolled hypertension but were on less than three antihypertensive agents. Independent predictors of RH were age (risk ratio, RR = 1.08, 95% confidence interval, CI 1.05-1.12, p < 0.001), body mass index (RR = 1.06, 95% CI 1.00-1.13, p < 0.05) and the presence of the metabolic syndrome (MetS) (RR = 2.01, 95% CI 1.03-3.91, p < 0.05).

CONCLUSIONS

RH is frequent in patients followed up in hypertension outpatient clinics. In addition to age and obesity, MetS appears to be associated with increased risk for RH. Clarification of the mechanisms underpinning the association between MetS and hypertension might reduce the prevalence of RH.

Reversal of genetic salt-sensitive hypertension by targeted sympathetic ablation

The sympathetic nervous system plays an important role in some forms of human hypertension as well as the Dahl salt-sensitive rat model of hypertension; however, the sympathetic targets involved remain unclear. To address this, we examined the role of the renal and splanchnic sympathetic nerves in Dahl hypertension by performing sham surgery (n=10) or targeted sympathetic ablation of the renal nerves (renal denervation, n=11), the splanchnic nerves (celiac ganglionectomy, n=11), or both renal and splanchnic nerves (n=11) in hypertensive Dahl rats. Mean arterial pressure increased from ≈120 mm Hg, while on a 0.1% sodium chloride diet, to ≈140 mm Hg after being fed a 4.0% sodium chloride diet for 3 weeks. At that point, rats underwent sham or targeted sympathetic ablation. Four weeks after treatment, mean arterial pressure was lower in renal denervated (150.4±10.4) and celiac ganglionectomized (147.0±6.1) rats compared with sham rats (165.0±3.7) and even lower in rats that underwent both ablations (128.4±6.6). There were no differences in heart rate or fluid balance between sham and renal denervated rats; however, rats that underwent either celiac ganglionectomy or both ablations exhibited marked tachycardia as well as sodium and water retention after treatment. These data suggest that targeted sympathetic ablation is an effective treatment for established hypertension in the Dahl rat and that the kidneys and the splanchnic vascular bed are both independently important targets of the sympathetic nervous system in this model.

Device therapy of resistant hypertension

It is well known that hypertension is an independent cardiovascular risk factor. Treatment of hypertension frequently includes administration of three or more drugs. Resistant hypertension is defined when blood pressure remains above target value despite full doses (the patient’s maximum tolerated dose) of antihypertensive medication consisting of at least three different classes of drugs including a diuretic. Pharmacological treatment of hypertension is often unsuccessful despite the increasing number of drug combinations. Uncontrolled hypertension, however, increases the cardiovascular risk. Device treatment of resistant hypertension is currently testing two major fields. One of them the stimulation of baroreceptors in the carotid sinus and the other is radiofrequency ablation of sympathetic nerve fibers around renal arteries to reduce blood pressure in drug resistant hypertension. Orv. Hetil., 2013, 154, 203–208.

Prognostic factors in resistant hypertension: implications for cardiovascular risk stratification and therapeutic management

Resistant hypertension (RH) is defined as uncontrolled office blood pressure (BP) in spite of the use of at least three antihypertensive medications. Although its condition has a high prevalence, it is still understudied, and its prognosis is not well established. Some prospective studies evaluated the prognostic value of ambulatory BP monitoring, ECG and renal parameters. They pointed out that ambulatory BPs are important predictors of cardiovascular morbidity and mortality, whereas office BP has no prognostic value. The diagnosis of true RH and the nondipping pattern are also valuable predictors of cardiovascular outcomes. Moreover, several ECG (prolonged ventricular repolarization, serial changes in the strain pattern and left ventricular hypertrophy) and renal parameters (albuminuria and reduced glomerular filtration rate) are also powerful cardiovascular risk markers in RH. These markers and others yet unexplored, such as arterial stiffness and serum biomarkers, may improve cardiovascular risk stratification in these very high-risk patients.

Influence of Lower Body Positive Pressure on Upper Airway Cross-Sectional Area in Drug-Resistant Hypertension

We previously showed that in hypertensive patients the amount of fluid displaced from the legs overnight is directly related to the severity of obstructive sleep apnea and that the rostral fluid shift was greater in drug-resistant hypertensive patients. The findings suggested that this fluid redistribution increases upper airway collapsibility, yet more direct evidence is lacking. The present study examines the effects of graded lower body positive pressure on leg fluid volume, upper airway cross-sectional area, and neck circumference in patients with drug-resistant hypertension (n=25) and controlled hypertension (n=15). In both groups, the reduction in mean upper airway cross-sectional area and oropharyngeal junction area, assessed by acoustic pharyngometry, and the increase in neck circumference, determined by mercury strain gauge plethysmography, were related to the amount of fluid displaced from the legs ( R 2 =0.41, P <0.0001; R 2 =0.42, P <0.0001; and R 2 =0.47, P <0.0001, respectively). Displacement of leg fluid volume was significantly greater in patients with drug-resistant hypertension than in controlled hypertension ( P <0.0001), and as a consequence, the former experienced greater reductions in mean upper airway cross-sectional area and oropharyngeal junction area ( P =0.001 and P <0.0001, respectively). The findings support the concept that in hypertensive subjects, rostral fluid displacement may participate in the pathogenesis of obstructive sleep apnea by narrowing the upper airway and making it more susceptible to collapse during sleep. The exaggerated fluid volume displacement from the legs and upper airway response to lower body positive pressure in patients with drug-resistant hypertension provide additional evidence of an important link between drug-resistant hypertension and obstructive sleep apnea.

Renal sympathetic denervation for treatment of resistant hypertension: a systematic review

Catheter-based renal sympathetic denervation (RSD) is a novel technique that is being investigated as treatment for resistant hypertension. To systematically evaluate the existing literature on the safety and efficacy of RSD in persons with resistant hypertension, online searches of Medline and the Cochrane Library Database (up to June 2012) were performed. Randomized controlled trials, observational studies, and conference proceedings published in English language were included. Nineteen studies (N=683 persons) were included. Follow-up duration ranged from 1 to 24 months. All studies reported significant reductions in systolic and diastolic pressures. Maximal reduction of blood pressure ranged from 18 mm Hg to 36 mm Hg (systolic) and 9 mm Hg to 15 mm Hg (diastolic). Sustained benefit of blood pressure reduction at 12 months was seen in 5 studies. No worsening of renal function was reported and there were few procedure-related adverse events such as pseudoaneurysm formation, hypotension, and bradycardia. Data from short-term studies suggest that RSD is a safe and effective therapeutic option in carefully selected patients with resistant hypertension. Long-term studies with large patient populations are needed to study whether this benefit is sustained with a demonstrable difference in cardiovascular disease event rates.

Prevalence and clinical profile of resistant hypertension among treated hypertensive subjects

We assessed prevalence and clinical characteristics of resistant hypertension (RH) and prevalence of false RH (white-coat effect [WCE] by home blood pressure [BP] monitoring), among a population of 302 treated hypertensive patients, mean age 66.6 (± 13.8), 67.5% women. Resistant hypertension was defined according to the American Heart Association criteria. Prevalence of RH was 10%, and the following five variables were independently associated with it: body mass index, diabetes, isolated systolic hypertension, orthostatic hypotension, and use of beta-blockers. Prevalence of WCE among subjects with office-RH was 27.6%. Our study identified easily measurable parameters related to RH. Standing BP should be systematically measured in individuals with RH.

Resistant hypertension: a frequent and ominous finding among hypertensive patients with atherothrombosis

AIMS

The effect of resistant hypertension on outcomes in patients with atherothrombotic disease is currently unknown. Accordingly, we sought to determine the prevalence and outcomes of resistant hypertension in stable hypertensive outpatients with subclinical or established atherothombotic disease enrolled in the international Reduction of Atherothrombosis for Continued Health (REACH) registry.

METHODS AND RESULTS

Resistant hypertension was defined as a blood pressure ≥140/90 mmHg at baseline (≥130/80 mmHg if diabetes/renal insufficiency) with the use of ≥3 antihypertensive medications, including a diuretic. The primary outcome was a composite of cardiovascular death, myocardial infarction, or stroke at 4 years. A total of 53 530 hypertensive patients were included. The prevalence of resistant hypertension was 12.7%; 6.2% on 3 antihypertensive agents, 4.6% on 4 agents, and 1.9% on ≥5 agents (mean: 4.7 ± 0.8). In addition to a diuretic, these patients were being treated mostly with ACE-inhibitors/angiotensin receptor blockers (90.1%), beta-blockers (67.0%), and calcium channel blockers (50.8%). Patients with resistant hypertension had a higher risk of the primary endpoint on multivariable analysis [hazard ratio (HR) 1.11, 95% confidence interval (CI) 1.02-1.20; P = 0.017], including an increased non-fatal stroke risk (HR: 1.26; 95% CI: 1.10-1.45; P = 0.0008). Hospitalizations due to congestive heart failure were higher (P < 0.0001). Patients on ≥5 agents had a higher adjusted risk for the primary endpoint when compared with those on ≤3 agents (P = 0.03).

CONCLUSION

The presence of resistant hypertension identifies a subgroup of patients with hypertension and atherothrombosis who are at heightened risk for adverse long-term outcomes.

Renal denervation: a potential new treatment for severe hypertension

Hypertension is a leading cause of cardiovascular morbidity and mortality. Drug-resistant hypertension remains common despite the availability of several classes of effective antihypertensive agents. Sympathetic hyperactivity has long been recognized as a major contributor to resistant hypertension, but radical sympathectomy was abandoned several decades ago due to its significant side effects. The newly developed, minimally invasive, catheter-based renal sympathetic denervation procedure has been shown in recent trials to produce impressive blood pressure reductions and a favorable safety profile in drug-resistant hypertension. Although the long-term efficacy and safety of renal denervation remains to be determined, emerging data suggest that the benefits of renal denervation may extend beyond blood pressure control.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Hyperaldosteronism as a common cause of resistant hypertension

Resistant hypertension affects an estimated 10-15 million American adults and is increasing in prevalence. The etiology of resistant hypertension is almost always multifactorial, including obesity, older age, high dietary salt, chronic kidney disease, and aldosterone excess. Classical primary aldosteronism and lesser degrees of aldosterone excess, possibly originating from visceral adipocytes, contribute broadly to antihypertensive treatment resistance. Treatment of resistant hypertension is predicated on appropriate lifestyle changes and use of effective combinations of antihypertensive agents from different classes. Blockade of aldosterone with spironolactone has been shown to be particularly effective for treatment of resistant hypertension. The antihypertensive benefit of spironolactone is not limited to patients with demonstrable hyperaldosteronism but instead can be effective in resistant hypertensive patients regardless of aldosterone levels. Chlorthalidone is a potent, long-acting thiazide-like diuretic and should be used preferentially to treat resistant hypertension as it is superior to normally used doses of hydrochlorothiazide.

[Renal denervation: current state and future perspectives]

Hypertension is a well-known risk factor for major cardiovascular events. Despite advances in medical therapy, sufficient treatment of hypertension remains unsatisfying in a substantial number of patients and is therefore one of the main challenges in modern medicine. In Germany 5-15 % of patients with hypertension suffer from resistant hypertension with elevated blood pressure despite the use of at least three antihypertensive drugs. Additionally patients often suffer from side effects. In patients with resistant hypertension the important role of the sympathetic nervous system with increased sympathetic activity is well known. In the past surgical sympathectomy with extended removal of sympathetic ganglia was performed to reduce blood pressure in patients with malignant hypertension. The positive effect of this highly invasive procedure on blood pressure led to the development of new strategies for the treatment of uncontrolled hypertension. One of the novel procedures includes catheter-based renal sympathetic denervation. The most common system is the radiofrequency ablation catheter (Symplicity®, Medtronic, Minneapolis, USA) which ablates the nerve fibers in the adventitia of the renal arteries by using high-frequency energy. As the results of the Symplicity trials (HTN-1 and HTN-2) showed significant reduction of systolic and diastolic blood pressure after renal denervation there is growing interest in this novel procedure. Moreover, by reducing the sympathetic activity after renal denervation early results indicate a positive impact on glucose metabolism, sleep apnea syndrome, as well as heart and renal failure. These effects led to the development of many different devices for renal denervation; however, trials with a higher number of patients and longer follow-up need to confirm these initially promising results and the value of newer devices. Until then renal denervation should not be regarded as standard therapy for arterial hypertension or an alternative to medical antihypertensive treatment and should be reserved for selected patients with resistant hypertension and specialized medical centres.

Sodium-retaining effect of insulin in diabetes

Insulin has long been hypothesized to cause sodium retention, potentially of enough magnitude to contribute to hypertension in obesity, metabolic syndrome, and Type II diabetes. There is an abundance of supportive evidence from correlational analyses in humans, acute insulin infusion studies in humans and animals, and chronic insulin infusion studies in rats. However, the absence of hypertension in human insulinoma patients, and negative results for sodium-retaining or blood pressure effects of chronic insulin infusion in a whole series of dog studies, strongly refute the insulin hypothesis. We recently questioned whether the euglycemic, hyperinsulinemia model used for most insulin infusion studies, including the previous chronic dog studies, was the most appropriate model to test the renal actions of insulin in obesity, metabolic syndrome, and Type II diabetes. In those circumstances, hyperinsulinemia coexists with hyperglycemia. Therefore, we tested the sodium-retaining effect of insulin in chronically instrumented, alloxan-treated diabetic dogs. We used 24 h/day intravenous insulin infusion to regulate plasma insulin concentration. Induction of diabetes (∼400 mg/dl) caused sustained natriuresis and diuresis. However, if we clamped insulin at baseline, control levels, i.e., prevented it from decreasing, then the sustained natriuresis and diuresis were completely reversed, despite the same level of hyperglycemia. We also found that 24 h/day intrarenal insulin infusion had the same effect in diabetic dogs but had no sodium-retaining action in normal dogs. This new evidence that insulin has a sodium-retaining effect during hyperglycemia may have implications for maintaining sodium balance in uncontrolled Type II diabetes.

Overview of resistant hypertension: A glimpse of the cardiologist's current standpoint

Hypertension is a major risk factor for cardiovascular disease, resulting in increased incidence of cerebrovascular events, ischaemic heart disease, heart failure, and renal impairment. Thus, it is one of the most important preventable causes of premature morbidity and mortality. Despite current knowledge on the management of hypertension and the availability of several effective antihypertensive medications, uncontrolled hypertension remains a common and challenging clinical problem. Resistant hypertension is a complex condition with multiple contributing factors and overlapping comorbidities. Although there is limited hard evidence regarding resistant hypertension, our understanding of this condition has improved recently. This article will present an overview of resistant hypertension and highlight recent publications about this topic.

Cost-effectiveness and clinical effectiveness of catheter-based renal denervation for resistant hypertension

OBJECTIVES

The purpose of this study was to assess cost-effectiveness and long-term clinical benefits of renal denervation in resistant hypertensive patients.

BACKGROUND

Resistant hypertension affects 12% of hypertensive persons. In the Symplicity HTN-2 randomized controlled trial, catheter-based renal denervation (RDN) lowered systolic blood pressure by 32 ± 23 mm Hg from 178 ± 18 mm Hg at baseline.

METHODS

A state-transition model was used to predict the effect of RDN and standard of care on 10-year and lifetime probabilities of stroke, myocardial infarction, all coronary heart disease, heart failure, end-stage renal disease, and median survival. We adopted a societal perspective and estimated an incremental cost-effectiveness ratio in U.S. dollars per quality-adjusted life-year, both discounted at 3% per year. Robustness and uncertainty were evaluated using deterministic and probabilistic sensitivity analyses.

RESULTS

Renal denervation substantially reduced event probabilities (10-year/lifetime relative risks: stroke 0.70/0.83; myocardial infarction 0.68/0.85; all coronary heart disease 0.78/0.90; heart failure 0.79/0.92; end-stage renal disease 0.72/0.81). Median survival was 18.4 years for RDN versus 17.1 years for standard of care. The discounted lifetime incremental cost-effectiveness ratio was $3,071 per quality-adjusted life-year. Findings were relatively insensitive to variations in input parameters except for systolic blood pressure reduction, baseline systolic blood pressure, and effect duration. The 95% credible interval for incremental cost-effectiveness ratio was cost-saving to $31,460 per quality-adjusted life-year.

CONCLUSIONS

The model suggests that catheter-based renal denervation, over a wide range of assumptions, is a cost-effective strategy for resistant hypertension that might result in lower cardiovascular morbidity and mortality.

Catheter-based renal denervation for resistant hypertension: rationale and design of the SYMPLICITY HTN-3 Trial

Hypertension represents a significant global public health concern, contributing to vascular and renal morbidity, cardiovascular mortality, and economic burden. The opportunity to influence clinical outcomes through hypertension management is therefore paramount. Despite adherence to multiple available medical therapies, a significant proportion of patients have persistent blood pressure elevation, a condition termed resistant hypertension. Recent recognition of the importance of the renal sympathetic and somatic nerves in modulating blood pressure and the development of a novel procedure that selectively removes these contributors to resistant hypertension represents an opportunity to provide clinically meaningful benefit across wide and varied patient populations. Early clinical evaluation with catheter-based, selective renal sympathetic denervation in patients with resistant hypertension has mechanistically correlated sympathetic efferent denervation with decreased renal norepinephrine spillover and renin activity, increased renal plasma flow, and has demonstrated clinically significant, sustained reductions in blood pressure. The SYMPLICITY HTN-3 Trial is a pivotal study designed as a prospective, randomized, masked procedure, single-blind trial evaluating the safety and effectiveness of catheter-based bilateral renal denervation for the treatment of uncontrolled hypertension despite compliance with at least 3 antihypertensive medications of different classes (at least one of which is a diuretic) at maximal tolerable doses. The primary effectiveness endpoint is measured as the change in office-based systolic blood pressure from baseline to 6 months. This manuscript describes the design and methodology of a regulatory trial of selective renal denervation for the treatment of hypertension among patients who have failed pharmacologic therapy.

Clinical differences between resistant hypertensives and patients treated and controlled with three or less drugs

BACKGROUND AND AIM

Clinical characteristics of resistant hypertensive patients in comparison to controlled patients have not been fully investigated in large cohorts. The aim of the study was to evaluate clinical differences, target organ damage and ambulatory blood pressure monitoring in resistant hypertensive patients and patients controlled on three or less drugs.

METHODS

In December 2010, from the Spanish Ambulatory Blood Pressure Monitoring Registry, we identified 14 461 patients fulfilling criteria of resistant hypertension and 13 436 hypertensive patients controlled on three or less drugs. Clinical characteristics were compared between these two groups.

RESULTS

Compared to controlled patients, those having resistant hypertension were older, more obese and had longer hypertension duration. They also had more frequently diabetes, dyslipidemia, reduced renal function, microalbuminuria, left-ventricular hypertrophy and previous history of cardiovascular events. In multivariate analyses, hypertension duration, obesity, abdominal obesity, left-ventricular hypertrophy, reduced estimated glomerular filtration rate, and microalbuminuria were independently associated with resistant hypertension. Resistant hypertensive patients had higher ambulatory blood pressures, but differences between office and ambulatory blood pressure (white-coat effect) were also more pronounced in this group, revealing a proportion of 40% of patients with normal 24-h blood pressure. On the contrary, values of 24-h blood pressure above 130 and/or 80 mmHg (masked hypertension) were present in 31% of apparently controlled patients.

CONCLUSION

Resistant hypertension is associated with obesity, longer hypertension duration and kidney and cardiac damage. Ambulatory blood pressure monitoring reveals that white-coat hypertension is common among resistant hypertensive patients, as well as is masked hypertension among apparently controlled patients.

Unilateral catheter-based renal sympathetic denervation in resistant arterial hypertension shows no blood pressure-lowering effect

A 68-year-old woman with resistant essential arterial hypertension despite the regular use of four antihypertensive drugs was referred to the catheter-based renal sympathetic denervation. Due to the complicated anatomy, insertion of the guiding catheter into the left renal artery was not stable. Thus, renal denervation of only the right renal artery was performed. Before and after renal denervation, the patient's blood pressure was monitored by home blood pressure (BP) telemonitoring. The average 7-day home BP telemonitoring values before and 1, 2, and 3 months after denervation were 187.1/124.1, 193.3/123.1, 198.3/129.6, and 195.2/128.0 mm Hg. After unilateral renal denervation, no BP decrease occurred. This unique case suggests that unilateral catheter-based renal sympathetic denervation in resistant arterial hypertension shows no BP-lowering effect. Therefore, when treating resistant hypertension by catheter-based renal denervation, it seems advisable to try always to perform an effective bilateral procedure.

Should ambulatory blood pressure monitoring be mandatory for future studies in resistant hypertension: a perspective

Recent technologic advances rekindled interventional management of resistant hypertension, either by carotid baroreceptor activation or renal sympathetic denervation. Interventional techniques result in impressive falls in office blood pressure (BP); however, ambulatory BP reductions are rather modest. This disparity between office and ambulatory BP reductions is observed with antihypertensive drugs, but at a much lower degree. Available explanations are not convincing, therefore, we propose that sympathetic overactivity may partially explain this divergence. Further studies are needed to prove or disprove our hypothesis.

Prevalence and correlates of low medication adherence in apparent treatment-resistant hypertension

Low medication adherence may explain part of the high prevalence of apparent treatment-resistant hypertension (aTRH). The authors assessed medication adherence and aTRH among 4026 participants taking ≥ 3 classes of antihypertensive medication in the population-based Reasons for Geographic and Racial Differences in Stroke (REGARDS) trial using the 4-item Morisky Medication Adherence Scale (MMAS). Low adherence was defined as an MMAS score ≥ 2. Overall, 66% of participants taking ≥ 3 classes of antihypertensive medication had aTRH. Perfect adherence on the MMAS was reported by 67.8% and 70.9% of participants with and without aTRH, respectively. Low adherence was present among 8.1% of participants with aTRH and 5.0% of those without aTRH (P<.001). Among those with aTRH, female sex, residence outside the US stroke belt or stroke buckle, physical inactivity, elevated depressive symptoms, and a history of coronary heart disease were associated with low adherence. In the current study, a small percentage of participants with aTRH had low adherence.

Renal responses to chronic suppression of central sympathetic outflow

Chronic electric activation of the carotid baroreflex produces sustained reductions in sympathetic activity and arterial pressure and is currently being evaluated as hypertension therapy for patients with resistant hypertension. However, the chronic changes in renal function associated with natural suppression of sympathetic activity are largely unknown. In normotensive dogs, we investigated the integrative cardiovascular effects of chronic baroreflex activation (2 weeks) alone and in combination with the calcium channel blocker amlodipine, which is commonly used in the treatment of resistant hypertension. During baroreflex activation alone, there were sustained decreases in mean arterial pressure (17±1 mmHg) and plasma (norepinephrine; ≈35%), with no change in plasma renin activity. Despite low pressure, sodium balance was achieved because of decreased tubular reabsorption, because glomerular filtration rate and renal blood flow decreased 10% to 20%. After 2 weeks of amlodipine, arterial pressure was also reduced 17 mmHg, but with substantial increases in norepinephrine and plasma renin activity and no change in glomerular filtration rate. In the presence of amlodipine, baroreflex activation greatly attenuated neurohormonal activation, and pressure decreased even further (by 11±2 mmHg). Moreover, during amlodipine administration, the fall in glomerular filtration rate with baroreflex activation was abolished. These findings suggest that the chronic blood pressure-lowering effects of baroreflex activation are attributed, at least in part, to sustained inhibition of renal sympathetic nerve activity and attendant decreases in sodium reabsorption before the macula densa. Tubuloglomerular feedback constriction of the afferent arterioles may account for reduced glomerular filtration rate, a response abolished by amlodipine, which dilates the preglomerular vasculature.

The association between medication adherence and treatment intensification with blood pressure control in resistant hypertension

Patients with resistant hypertension are at risk for poor outcomes. Medication adherence and intensification improve blood pressure (BP) control; however, little is known about these processes or their association with outcomes in resistant hypertension. This retrospective study included patients from 2002 to 2006 with incident hypertension from 2 health systems who developed resistant hypertension or uncontrolled BP despite adherence to ≥3 antihypertensive medications. Patterns of hypertension treatment, medication adherence (percentage of days covered), and treatment intensification (increase in medication class or dose) were described in the year after resistant hypertension identification. Then, the association between medication adherence and intensification with 1-year BP control was assessed controlling for patient characteristics. Of the 3550 patients with resistant hypertension, 49% were male, and mean age was 60 years. One year after resistance hypertension determination, fewer patients were taking diuretics (77.7% versus 92.2%; P<0.01), β-blockers (71.2% versus 79.4%; P<0.01), and angiotensinogen-converting enzyme inhibitor/angiotensin receptor blocker (64.8% versus 70.1%; P<0.01) compared with baseline. Rates of BP control improved over 1 year (22% versus 55%; P<0.01). During this year, adherence was not associated with 1-year BP control (adjusted odds ratio, 1.18 [95% CI: 0.94-1.47]). Treatment was intensified in 21.6% of visits with elevated BP. Increasing treatment intensity was associated with 1-year BP control (adjusted odds ratio, 1.64 [95% CI, 1.58-1.71]). In this cohort of patients with resistant hypertension, treatment intensification but not medication adherence was significantly associated with 1-year BP control. These findings highlight the need to investigate why patients with uncontrolled BP do not receive treatment intensification.

Interferon-γ ablation exacerbates myocardial hypertrophy in diastolic heart failure

Diastolic heart failure (HF) accounts for up to 50% of all HF admissions, with hypertension being the major cause of diastolic HF. Hypertension is characterized by left ventricular (LV) hypertrophy (LVH). Proinflammatory cytokines are increased in LVH and hypertension, but it is unknown if they mediate the progression of hypertension-induced diastolic HF. We sought to determine if interferon-γ (IFNγ) plays a role in mediating the transition from hypertension-induced LVH to diastolic HF. Twelve-week old BALB/c (WT) and IFNγ-deficient (IFNγKO) mice underwent either saline (n = 12) or aldosterone (n = 16) infusion, uninephrectomy, and fed 1% salt water for 4 wk. Tail-cuff blood pressure, echocardiography, and gene/protein analyses were performed. Isolated adult rat ventricular myocytes were treated with IFNγ (250 U/ml) and/or aldosterone (1 μM). Hypertension was less marked in IFNγKO-aldosterone mice than in WT-aldosterone mice (127 ± 5 vs. 136 ± 4 mmHg; P < 0.01), despite more LVH (LV/body wt ratio: 4.9 ± 0.1 vs. 4.3 ± 0.1 mg/g) and worse diastolic dysfunction (peak early-to-late mitral inflow velocity ratio: 3.1 ± 0.1 vs. 2.8 ± 0.1). LV ejection fraction was no different between IFNγKO-aldosterone vs. WT-aldosterone mice. LV end systolic dimensions were decreased significantly in IFNγKO-aldosterone vs. WT-aldosterone hearts (1.12 ± 0.1 vs. 2.1 ± 0.3 mm). Myocardial fibrosis and collagen expression were increased in both IFNγKO-aldosterone and WT-aldosterone hearts. Myocardial autophagy was greater in IFNγKO-aldosterone than WT-aldosterone mice. Conversely, tumor necrosis factor-α and interleukin-10 expressions were increased only in WT-aldosterone hearts. Recombinant IFNγ attenuated cardiac hypertrophy in vivo and modulated aldosterone-induced hypertrophy and autophagy in cultured cardiomyocytes. Thus IFNγ is a regulator of cardiac hypertrophy in diastolic HF and modulates cardiomyocyte size possibly by regulating autophagy. These findings suggest that IFNγ may mediate adaptive downstream responses and challenge the concept that inflammatory cytokines mediate only adverse effects.

Trends in hypertension prevalence, awareness, treatment, and control rates in Shandong Province of China

The authors retrospectively examined data from 3 surveys on hypertension according to the 2010 Chinese Guidelines for the Management of Hypertension. These surveys were conducted in 1991, 1999, and 2007, and included 85,371 individuals 18 years and older who were living in Shandong Province, China. Age-standardized prevalent hypertension increased from 15.6% in 1991 to 17.3% in 1999 and 32.7% in 2007 (both P<.0001). The ascending prevalence can be partially explained by increasing body weight. Among individuals with hypertension, awareness increased significantly from 27.8% in 1991 to 39.1% in 1999 and 49.2% in 2007. The proportion of pharmacologic treatment also considerably improved, with the estimate of 12.9%, 28.1%, and 43.3% in the 3 surveys, respectively. Hypertension control increased from 3.0% to 4.4% to 7.1% in the past 20 years. The upward trend in blood pressure control was mostly attributable to a rise among men and persons at middle age. This study suggests that the prevalence of hypertension increased in the Shandong population from 1991 to 2007. Although substantially improved, control rates were still unacceptably low. Comprehensive strategies are urgently required to put into practice for the management of hypertension in Shandong Province, China.

[Frequency of hypertension resistant to treatment and indication for renal denervation]

OBJECTIVE

To evaluate in hypertensive patients followed in a specialized hypertension unit, the prevalence of subjects uncontrolled despite triple therapy including a diuretic. The aim is to estimate the percentage of hypertensive patients with an indication to renal denervation.

METHOD

From a database of computerized medical records of a unit specialized in hypertension, it was extracted 144 consecutive cases of subjects treated and followed for at least 1year and having had a home pressure monitoring (HPM) on treatment, and if necessary a work-up for a secondary hypertension. The blood pressure (BP) was evaluated in office by automated method (after 2 and 8minutes) and with HPM (average of three measurements in the morning and evening for three consecutive days).

RESULTS

The population has the following characteristics: age 62 with 26% over 70years, treated dyslipidemia (39%), treated diabetes (11%), adrenal hypertension treated medically (14%), severe renal failure (3%). The means of treatment are: a monotherapy (33%), bitherapy (35%), triple therapy (17%), quadritherapy (7%), pentatherapy or more (1%), spironolactone (45%), thiazide diuretics (49%). The uncontrolled hypertension was observed in 26% if the BP is evaluated with HPM, in 52% if the BP is evaluated at the office after 2minutes of rest and 7% if the BP is evaluated after 8minutes of rest (P<0.01). In patients treated with at least a tritherapy in association with a diuretic, an uncontrolled hypertension was observed in 5% if the BP is evaluated with HPM. Failure to control for the SBP is the cause of 80% of resistant hypertension.

CONCLUSION

The frequency of resistant hypertension is 5% of hypertensive patients followed in a specialized hypertension unit when guidelines are applied in the case of uncontrolled hypertension. These results indicate that the indication for renal denervation affects only a small percentage of patients treated for hypertension.

Expert consensus: Renal denervation for the treatment of hypertension

Catheter-based renal denervation is a new method able to disrupt renal sympathetic nerves located in the adventitia of renal arteries. A randomized clinical trial showed a decrease in blood pressure in resistant hypertensive patients. In order to guide clinicians and interventional practitioner for the use of this new approach, different French scientific societies (Hypertension, Cardiology and Radiology) decided to combine their expertise and propose an expert consensus to assess benefit/risk ratio of this technique in the field of arterial hypertension. In 2012, this expert consensus propose to limit renal denervation technique to patients with essential hypertension uncontrolled by four or more antihypertensive therapies with at least one treatment being a diuretic and spironolactone at a dose of 25mg shown to be unable to control blood pressure. Measurement of office BP should be at least with SBP more than 160mmHg and/or DBP more than 100mmHg confirmed by ambulatory BP measurement (home or ABP measurement with SBP more than 135mmHg and DBP more than 85mm during daytime period). Finally, renal artery anatomy and function should allow proper intervention (i.e., two functional kidneys, absence of previous renal angioplasty). Renal enervation is a complex interventional procedure with potentially arterial complications, training is required for practitioners. Antihypertensive treatment should not be interrupted immediately after renal denervation since blood pressure lowering effect are delayed and reached maximum effect after 3 months. Monitoring of blood pressure, renal function and anatomy of renal arteries is required 12 months and 36 months after procedure. The expert consensus requires the inclusion of patients experiencing this procedure in a observational study with record form and follow-up.

Mineralocorticoid receptor-associated hypertension and its organ damage: clinical relevance for resistant hypertension

The role of aldosterone in the pathogenesis of hypertension and cardiovascular diseases has been clearly shown in congestive heart failure and endocrine hypertension due to primary aldosteronism. In resistant hypertension, defined as a failure of concomitant use of three or more different classes of antihypertensive agents to control blood pressure (BP), add-on therapy with mineralocorticoid receptor (MR) antagonists is frequently effective, which we designate as "MR-associated hypertension". The MR-associated hypertension is classified into two subtypes, that with elevated plasma aldosterone levels and that with normal plasma aldosterone levels. The former subtype includes primary aldosteronism (PA), aldosterone-associated hypertension which exhibited elevated aldosterone-to-renin ratio and plasma aldosterone levels, but no PA, aldosterone breakthrough phenomenon elicited when angiotensin-converting enzyme inhibitor (ACE-I) or angiotensin II receptor blocker (ARB) is continued to be given, and obstructive sleep apnea. In contrast, the latter subtype includes obesity, diabetes mellitus, chronic kidney disease (CKD), and polycystic ovary syndrome (PCOS). The pathogenesis of MR-associated hypertension with normal plasma aldosterone levels is considered to be mediated by MR activation by pathways other than high aldosterone levels, such as increased MR levels, increased MR sensitivity, and MR overstimulation by other factors such as Rac1. For resistant hypertension with high plasma aldosterone levels, MR antagonist should be given as a first-line therapy, whereas for resistant hypertension with normal aldosterone levels, ARB or ACE-I should be given as a first-line therapy and MR antagonist would be given as an add-on agent.

Recent advancements in the treatment of resistant hypertension

The 2008 scientific statement from the American Heart Association defined resistant hypertension as blood pressure remaining above goal (< 140/90 mm Hg for the general population and < 130/80 mm Hg for patients with diabetes or renal disease) despite the concurrent use of optimal doses of 3 antihypertensive agents of different classes, ideally including a diuretic. Since then, there has been increasing recognition and characterization of patients with resistant hypertension and development of treatment strategies to treat this high-risk population. The role of aldosterone in resistant hypertension has gained increasing recognition. In particular, there has been development of a strong body of evidence for the use of spironolactone as a highly effective antihypertensive agent. Furthermore, there is increasing evidence to link aldosterone with both resistant hypertension and obstructive sleep apnea, with preliminary studies suggesting that aldosterone antagonists may potentially be effective in treating both conditions. Finally, recent work has directed increased attention toward novel invasive strategies for the treatment of resistant hypertension, specifically baroreflex activation therapy with carotid stimulation and percutaneous renal artery denervation. Initial randomized controlled trials have shown that both of these methods may be used to safely lower blood pressure, thereby providing exciting and promising new tools in the armamentarium of options to treat resistant hypertension.

Resistant hypertension and aldosterone: an update

Resistant hypertension (RHTN) is defined as a blood pressure remaining above goal despite the concurrent use of 3 antihypertensive medications of different classes, including, ideally a diuretic. RHTN is an important health problem with a prevalence rate expected to increase as populations become older, more obese, and at higher risk of having diabetes and chronic kidney disease, all of which are important risk factors for development of RHTN. The role of aldosterone has gained increasing recognition as a significant contributor to antihypertensive treatment resistance. In prospective studies, the prevalence of primary aldosteronism (PA) has ranged from 14%-21% in patients with RHTN, which is considerably higher than in the general hypertensive population. Furthermore, marked antihypertensive effects are seen when mineralocorticoid antagonists are added to the treatment regimen of patients with RHTN, further supporting aldosterone excess as an important cause of RHTN. A close association exists between hyperaldosteronism, RHTN, and obstructive sleep apnea (OSA) based upon recent studies which indicate that OSA is worsened by aldosterone-mediated fluid retention. This interaction is supported by preliminary data which demonstrates improvement in OSA severity after treatment with spironolactone.

Factors associated with lack of awareness and uncontrolled high blood pressure among Canadian adults with hypertension

BACKGROUND

Approximately 17% of Canadians with high blood pressure were unaware of their condition, and of Canadians aware of having the condition, approximately 1 in 5 have uncontrolled high blood pressure despite high rates of pharmacotherapy. The objectives of the current study are to estimate the prevalence of resistant hypertension and examine factors associated with (1) lack of awareness and (2) uncontrolled hypertension despite pharmacotherapy.

METHODS

Using the 2007-2009 Canadian Health Measures Survey (N = 3473, aged 20-79 years) and logistic regression, we quantified relationships between characteristics and (1) presence of hypertension, (2) lack of awareness (among those with hypertension), and (3) uncontrolled high blood pressure (among those treated for hypertension).

RESULTS

Older age, lowest income, and less than high school education were associated with presence of hypertension. Men (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.1-2.2) and adults < 60 years (OR, 1.7; 95% CI, 1.1-2.6) were more likely than others to be unaware. Among those aged 60+ years, women were more likely than men to have uncontrolled high blood pressure (OR, 2.4; 95% CI, 1.1-5.2) despite treatment. Elevated systolic blood pressure was the issue in over 90% of women and 80% of men with uncontrolled hypertension. Depending on the definition employed, 4.4% (95% CI, 2.4-6.4) to 7.8% (95% CI, 6.0-9.6) of the population with hypertension had resistant hypertension.

CONCLUSIONS

Messaging or interventions encouraging screening may be helpful for all younger Canadian adults and men; programs encouraging blood pressure control may help older women.

Incidence and prognosis of resistant hypertension in hypertensive patients

BACKGROUND

Despite a recent American Heart Association (AHA) consensus statement emphasizing the importance of resistant hypertension, the incidence and prognosis of this condition are largely unknown.

METHODS AND RESULTS

This retrospective cohort study in 2 integrated health plans included patients with incident hypertension in whom treatment was begun between 2002 and 2006. Patients were followed up for the development of resistant hypertension based on AHA criteria of uncontrolled blood pressure despite use of ≥3 antihypertensive medications, with data collected on prescription filling information and blood pressure measurement. We determined incident cardiovascular events (death or incident myocardial infarction, heart failure, stroke, or chronic kidney disease) in patients with and without resistant hypertension with adjustment for patient and clinical characteristics. Among 205 750 patients with incident hypertension, 1.9% developed resistant hypertension within a median of 1.5 years from initial treatment (0.7 cases per 100 person-years of follow-up). These patients were more often men, were older, and had higher rates of diabetes mellitus than nonresistant patients. Over 3.8 years of median follow-up, cardiovascular event rates were significantly higher in those with resistant hypertension (unadjusted 18.0% versus 13.5%, P<0.001). After adjustment for patient and clinical characteristics, resistant hypertension was associated with a higher risk of cardiovascular events (hazard ratio, 1.47; 95% confidence interval, 1.33-1.62).

CONCLUSIONS

Among patients with incident hypertension in whom treatment was begun, 1 in 50 patients developed resistant hypertension. Patients with resistant hypertension had an increased risk of cardiovascular events, which supports the need for greater efforts toward improving hypertension outcomes in this population.

Transcatheter renal artery sympathetic denervation for resistant hypertension: an old paradigm revisited

Resistant hypertension, defined as the failure to achieve target blood pressure despite concurrent use of 3 antihypertensive agents of different classes, is estimated to affect 20-30% of hypertensive patients. These patients are vulnerable to cardiovascular, cerebrovascular and renal complications. There is ample evidence that sympathetic nervous system hyperactivity contributes to the initiation, maintenance and progression of hypertension. The renal sympathetic nervous system, in particular, has been identified as a major culprit for the development and progression of hypertension, heart failure and chronic kidney disease in both preclinical and human studies. Traditional surgical sympathectomy proposed in 1940s was halted due to unacceptable operative risk and the emergence of anti-hypertensive medications. Recently, catheter-based renal sympathetic denervation by radiofrequency ablation has shown encouraging intermediate-term results with minimal complications in patients with resistant hypertension. This review summarizes the patho-physiological role of the renal sympathetic nervous system and the potential application of renal denervation therapy for the treatment of resistant hypertension.