High prevalence of cardiac and extracardiac target organ damage in refractory hypertension

Electrical carotid sinus stimulation: chances and challenges in the management of treatment resistant arterial hypertension

Treatment resistant arterial hypertension is associated with excess cardiovascular morbidity and mortality. Electrical carotid sinus stimulators engaging baroreflex afferent activity have been developed for such patients. Indeed, baroreflex mechanisms contribute to long-term blood pressure control by governing efferent sympathetic and parasympathetic activity. The first-generation carotid sinus stimulator applying bilateral bipolar stimulation reduced blood pressure in a controlled clinical trial but nevertheless failed to meet the primary efficacy endpoint. The second-generation device utilizes smaller unilateral unipolar electrodes, thus decreasing invasiveness of the implantation while saving battery. An uncontrolled clinical study suggested improvement in blood pressure with the second-generation device. We hope that these findings as well as preliminary observations suggesting cardiovascular and renal organ protection with electrical carotid sinus stimulation will be confirmed in properly controlled clinical trials. Meanwhile, we should find ways to better identify patients who are most likely to benefit from electrical carotid sinus stimulation.

Sleep-disordered breathing and resistant hypertension

Hypertension is a highly prevalent problem worldwide, affecting at least one third of the adult general population. Although the exact prevalence is uncertain, it is estimated that at least 15% to 20% of individuals with hypertension have resistant hypertension. Resistant hypertension has been shown to predict more adverse cardiovascular and renal outcomes. In 2003, the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure recognized obstructive sleep apnea (OSA) as an important cause of secondary hypertension. A large body of epidemiologic evidence has linked OSA to resistant hypertension, nondipping nocturnal blood pressure, as well as target organ damage, including left ventricular hypertrophy, arterial stiffness, and microalbuminuria. The importance of OSA as a risk factor for the development of hypertension independent of other confounding factors also was observed in a prospective longitudinal study. More importantly, OSA predicts an increased risk of adverse cardiovascular outcomes, mortality, and sudden cardiac death. This article discusses the associations between OSA and resistant hypertension and reviews the latest understanding on the pathophysiologic mechanisms of hypertension in OSA. Nocturnal continuous positive airway pressure therapy is regarded as the standard treatment for OSA. Prospective randomized controlled trials and meta-analyses of prospective randomized controlled trials within the past 10 years that have examined the effects of continuous positive airway pressure therapy on blood pressure control in patients with OSA with or without hypertension are reviewed and summarized. The majority of the trials suggest a modest but significant benefit on blood pressure control with continuous positive airway pressure therapy. Whether continuous positive airway pressure therapy may improve hard outcomes of patients with OSA and resistant hypertension warrants further investigation.

Assessment of Mean Platelet Volume in Patients with Resistant Hypertension, Controlled Hypertension and Normotensives

OBJECTIVE

Patients with resistant hypertension are at increased risk for cardiovascular events. Mean platelet volume (MPV) is an accepted biomarker of platelet activation and considered as a risk factor for cardiovascular disease. The aim of this study was to determine whether MPV levels are higher in resistant hypertensive (RHTN) patients than in controlled hypertensive (CHTN) patients and healthy normotensive controls.

MATERIALS AND METHODS

279 consecutive patients were included in this study. Patients were divided into three groups: Resistant hypertension patient group [n=78; mean age 56.8±9.8; 42 males (53.8%)]; controlled hypertension patient group [n=121; mean age 54.1±9.6; 49 males (40.5%)]; and normotensive control group [n=80; mean age 49.8±8.5; 34 males (42.5%)]. Physical examination, laboratory work-up, and 24-hour ambulatory blood pressure measurement (ABPM) were performed in all participants.

RESULTS

The mean platelet volume levels were significantly higher in RHTN group than in the CHTN and normotensive groups (p<0.001). In correlation analysis office systolic and diastolic blood pressure was positively correlated with MPV.

CONCLUSION

Our study demonstrated that MPV, as an important indicator of platelet activation, was statistically higher in RHTN patients than in CHTN and in normotensive subjects. Elevated MPV levels may help to determine a high risk group for atherosclerosis in RHTN patients.

Cardiovascular and renal complications in patients with resistant hypertension

With an increased prevalence, resistant hypertension is recognized as an entity with a high cardiovascular morbidity and mortality. In a large cohort of patients with resistant hypertension, the crude incidence rate of total cardiovascular events reached 4.32 per 100 patient-years of follow-up (19.6 %), with a cardiovascular mortality of 8.3 % (incidence rate of 1.72 per 100 patient-years). Cardiovascular event rates are significantly higher in resistant hypertensives compared with non-resistant (18.0 % versus 13.5 %). In the same way, the prevalence of established cardiovascular and renal disease, as the asymptomatic organ damage (represented by left ventricular hypertrophy, carotid wall thickening, arterial stiffness, and microalbuminuria) is higher in these patients. Many studies have demonstrated a strong association between damage to these organs with higher blood pressure levels, the diagnosis of true resistant hypertension, and refractory hypertension. All efforts should be employed in order to control blood pressure and also to regress and/or prevent subclinical cardiovascular and renal damage. The focus should be on prevention of cardiovascular and renal complications, improving the prognosis of resistant hypertension.

Comparative risk of renal, cardiovascular, and mortality outcomes in controlled, uncontrolled resistant, and nonresistant hypertension

We sought to compare the risk of end stage renal disease (ESRD), ischemic heart event (IHE), congestive heart failure (CHF), cerebrovascular accident (CVA), and all-cause mortality among 470,386 individuals with resistant and nonresistant hypertension (non-RH). Resistant hypertension (60,327 individuals) was sub-categorized into 2 groups; 23,104 patients with cRH (controlled on 4 or more medicines) and 37,223 patients with uRH (uncontrolled on 3 or more medicines) in a 5 year retrospective cohort study. Cox proportional hazard modeling was used to estimate hazard ratios adjusting for age, gender, race, body mass index, chronic kidney disease (CKD), and co-morbidities. Resistant hypertension (cRH and uRH) compared to non-RH, had multivariable adjusted hazard ratios (95% confidence intervals) of 1.32 (1.27–1.37), 1.24 (1.20–1.28), 1.46 (1.40–1.52), 1.14 (1.10–1.19), and 1.06 (1.03–1.08) for ESRD, IHE, CHF, CVA, and mortality, respectively. Comparison of uRH to cRH had hazard ratios of 1.25 (1.18–1.33), 1.04 (0.99–1.10), 0.94 (0.89–1.01), 1.23 (1.14–1.31), and 1.01 (0.97–1.05) for ESRD, IHE, CHF, CVA, and mortality, respectively. Males and Hispanics had greater risk for ESRD within all 3 cohorts. Resistant hypertension had greater risk for ESRD, IHE, CHF, CVA, and mortality. The risk of ESRD and CVA and were 25% and 23% greater, respectively, in uRH compared to cRH supporting the linkage between blood pressure and both outcomes.

Mineralocorticoid Receptor Antagonists Therapy in Resistant Hypertension: Time to Implement Guidelines!

Despite the availability of anti-hypertensive medications with increasing efficacy up to 50% of hypertensive patients have blood pressure levels (BP) not at the goals set by international societies. Some of these patients are either not optimally treated or are non-adherent to the prescribed drugs. However, a proportion, despite adequate treatment, have resistant hypertension (RH), which represents an important problem in that it is associated to an excess risk of cardiovascular events. Notwithstanding a complex pathogenesis, an abundance of data suggests a key contribution for the mineralocorticoid receptor (MR) in RH, thus fostering a potential role for its antagonists in RH. Based on these premises randomized clinical trials aimed at testing the efficacy of MR antagonists (MRAs) in RH patients have been completed. Overall, they demonstrated the efficacy of MRAs in reducing BP and surrogate markers of target organ damage, such as microalbuminuria, either compared to placebo or to other drugs. In summary, owing to the key role of the MR in the pathogenesis of RH and on the proven efficacy of MRAs we advocate their inclusion as an essential component of therapy in patients with presumed RH. Conversely, we propose that RH should be diagnosed only in patients whose BP values show to be resistant to an up-titrated dose of these drugs.

Predictors of silent myocardial ischemia in resistant hypertensive patients

BACKGROUND

Hypertension is the most prevalent and significant modifiable risk factor for coronary heart disease. A portion of patients with uncontrolled hypertension are considered to have resistant hypertension (RHTN). Myocardial ischemia incidence increases along with blood pressure (BP) levels. However, the prevalence of myocardial ischemia in patients with RHTN, as well as the factors associated with it, is unknown.

METHODS

We enrolled 129 patients with true RHTN regularly followed in our specialty hypertension clinic and evaluated then by resting and dipyridamole pharmacological stress myocardial perfusion scintigraphy. Patients were then divided into 2 groups: those with (I-RHTN; n = 36) and those without (NI-RHTN; n = 93) myocardial ischemia. Echocardiography, 24-hour ambulatory BP monitoring (ABPM), and flow mediated dilation (FMD) were also evaluated.

RESULTS

Thirty six (28%) patients had myocardial ischemia. There was no difference between groups regarding age, sex, biochemical parameters, office, and 24-hour ABPM levels. Patients in the I-RHTN group were more likely diabetic (31% vs. 11%; P < 0.05) and obese (75% vs. 40%; P < 0.001). Adjusting for age and body mass index, multiple logistic regression showed that diabetes (odds ratio (OR) = 6.5; 95% confidence interval (CI) = 1.06-40.14; P = 0.04), FMD (OR = 0.18; 95% CI = 0.07-0.41; P < 0.001), heart rate (OR = 1.23; 95% CI = 1.11-1.36; P < 0.001), left ventricular mass index (OR = 1.02; 95% CI = 1.01-1.04; P = 0.04), and microalbuminuria (OR = 1.02; 95% CI = 1.01-1.04; P = 0.002) were independent predictors of ischemia.

CONCLUSIONS

In conclusion, there is a high prevalence of myocardial ischemia in patients with RHTN. Increased microalbuminuria, heart rate, endothelial dysfunction, and left ventricular mass can be useful to guide the investigation for myocardial ischemia in these high risk patients.

[Therapy-resistant hypertension]

BACKGROUND

Therapy-resistant hypertension is commonly encountered in daily practice. It is present when the therapeutic goal is not achieved after trying at least three antihypertensives from different groups with adequate doses and including a diuretic. Between 10 and 20% of patients are affected and their prognosis is poor. Thus, intensive strategies are required to achieve normotension.

DIAGNOSIS

An exact diagnosis is essential. Pseudoresistance needs to be excluded in addition to secondary hypertension and sleep apnea syndrome. The most common cause of pseudoresistance is incorrect blood pressure measurement, false estimation of the real blood pressure level, lack of compliance, unhealthy lifestyle, and drug interactions. Therapeutic resistance should not be diagnosed without 24 h ambulatory blood pressure measurement. This significantly reduces the total number of "resistant" patients.

THERAPY

Successful control of blood pressure is achieved in the majority of patients by taking advantage of all possible therapy options. Treatment with 4-6 antihypertensive drugs is justified because of the improvement of cardiovascular prognosis. However, prerequisite is the absence of undesirable side effects which is the most important condition for adequate and reliable patient compliance. Only in the case of failure of the above therapy options can invasive procedures--renal denervation and baroreflex activation therapy--be applied as they are still experimental. Successful management of patients with resistant hypertension is only possible with intensive and time-consuming physician-patient relationships.

Resistant hypertension: do all definitions describe the same patients?

Resistant hypertension (RH) is defined as blood pressure (BP) that remains ⩾140 and/or 90 mm Hg despite therapy with ⩾3 full-dose antihypertensive drugs (classical definition=CD). A definition proposed subsequently (new definition=ND) includes patients requiring ⩾4 drugs irrespective of BP values. We aimed to evaluate whether both definitions characterize the same kind of patients.One hundred and twenty-four consecutively attended patients with RH were classified into two groups according to their BP control: 66 patients had non-controlled BP (all those who met the CD criteria plus a few patients who met the ND criteria); 58 patients had controlled BP (all with RH according to the ND). Clinical, laboratory and office BP data were recorded. RH patients with non-controlled BP were more frequently diabetic (72% vs 49%), and had higher plasmatic glucose (149 vs 130 mg dl(-1)), cholesterol (179 vs 164 mg dl(-1)), low-density lipoprotein (LDL)-cholesterol (107 vs 95 mg dl(-1)) and triglyceride (169 vs 137 mg dl(-1)) levels; P<0.05 for all comparisons. In multivariate logistic regression analysis, the variables that independently associated with non-controlled BP were diabetes (P=0.001) and higher LDL-cholesterol (P=0.007).We conclude that, although both cohorts of patients are phenotypically quite similar, uncontrolled RH patients have higher prevalence of diabetes mellitus and higher LDL-cholesterol levels than controlled RH patients.

[New invasive therapies for management of resistant hypertension]

The failure of pharmacological approaches to treat resistant hypertension has stimulated interest in invasive device-based treatments. New catheter systems using radiofrequency or ultrasound energy have been developed, allowing a percutaneous endovascular approach to renal denervation for patients with resistant hypertension. To date, this technique has been evaluated only in a few open-label trials including small numbers and the available evidence suggests a favorable blood pressure-lowering effect in the short-term and a low incidence of immediate complications. All studies published to date have several limitations due to their open-label design. Carotid baroreceptor stimulation requires surgical implantation of electrodes connected to a stimulator. Preliminary results show a positive effect on blood pressure with a complication rate similar to the implantation of a pacemaker. In this context, there are arguments against an uncontrolled use of these procedures in routine practice: an unknown benefit/risk ratio, a variable blood pressure response, absence of cost-effectiveness evaluation. The indications of these procedures should follow the 2013 European Society of Hypertension guidelines. A strict follow-up of patients remains necessary at best by including them in clinical trials or international registries.

Large-scale gene-centric analysis identifies polymorphisms for resistant hypertension

Background

Resistant hypertension (RHTN), defined by lack of blood pressure (BP) control despite treatment with at least 3 antihypertensive drugs, increases cardiovascular risk compared with controlled hypertension. Yet, there are few data on genetic variants associated with RHTN.

Methods and Results

We used a gene‐centric array containing ≈50 000 single‐nucleotide polymorphisms (SNPs) to identify polymorphisms associated with RHTN in hypertensive participants with coronary artery disease (CAD) from INVEST‐GENES (the INnternational VErapamil‐SR Trandolapril STudy—GENEtic Substudy). RHTN was defined as BP≥140/90 on 3 drugs, or any BP on 4 or more drugs. Logistic regression analysis was performed in European Americans (n=904) and Hispanics (n=837), using an additive model adjusted for age, gender, randomized treatment assignment, body mass index, principal components for ancestry, and other significant predictors of RHTN. Replication of the top SNP was conducted in 241 European American women from WISE (Women's Ischemia Syndrome Evaluation), where RHTN was defined similarly. To investigate the functional effect of rs12817819, mRNA expression was measured in whole blood. We found ATP2B1 rs12817819 associated with RHTN in both INVEST European Americans (P‐value=2.44×10⁻³, odds ratio=1.57 [1.17 to 2.01]) and INVEST Hispanics (P=7.69×10⁻⁴, odds ratio=1.76 [1.27 to 2.44]). A consistent trend was observed at rs12817819 in WISE, and the INVEST‐WISE meta‐analysis result reached chip‐wide significance (P=1.60×10⁻⁶, odds ratio=1.65 [1.36 to 1.95]). Expression analyses revealed significant differences in ATP2B1 expression by rs12817819 genotype.

Conclusions

The ATP2B1 rs12817819 A allele is associated with increased risk for RHTN in hypertensive participants with documented CAD or suspected ischemic heart disease.

Clinical Trial Registration

URL: www.clinicaltrials.gov; Unique identifiers: NCT00133692 (INVEST), NCT00000554 (WISE).

Dynamic resistant hypertension patterns as predictors of cardiovascular morbidity: a 4-year prospective study

OBJECTIVE

Little is known regarding the clinical course and prognosis of resistant hypertension (RHT). We evaluated predictors of persistent RHT and the associated cardiovascular risk.

METHODS

We studied 1911 treated hypertensive patients (aged 59±11 years, 49% men) for a mean period of 3.9 years. At baseline, clinical data were collected and patients underwent echocardiographic measurements, routine blood testing and additional workup for exclusion of secondary causes of RHT (office-based uncontrolled hypertension under at least three drugs including a diuretic or controlled hypertension under four or more drugs). Endpoint of interest was the composite of coronary artery disease and stroke.

MAIN RESULTS

Four groups were identified depending on presence or absence of RHT at baseline and follow-up: 1153 patients (60%) never having RHT, 189 (10%) with resolved RHT, 204 (11%) with incident RHT and 365 (19%) with persistent RHT. Two-thirds of the patients with RHT at baseline remained resistant at the end of the study. Independent variables associated with both incident and persistent RHT were diabetes mellitus, history of cardiovascular disease, hypertension duration, SBP, left ventricular hypertrophy and glomerular filtration rate. Persistent RHT compared with never-having RHT was associated with a 2.2-fold increased risk for cardiovascular morbidity (95% CI: 1.21-4.05, P = 0.01) after adjustment for risk factors.

CONCLUSION

In treated hypertensive patients, among prospective RHT dynamic patterns, persistent RHT is frequent and independently associated with adverse cardiovascular prognosis.

Patients with resistant hypertension have more peripheral arterial disease than other uncontrolled hypertensives

The aim of this study was to investigate whether resistant hypertension differs from uncontrolled and controlled hypertension in terms of target organ damage. Hypertensive subjects with antihypertensive medication (n=385) were identified in a population survey conducted in southwestern Finland. None of the study subjects had previously diagnosed cardiovascular or renal disease or diabetes. Ankle-brachial index, estimated glomerular filtration rate, electrocardiogram-determined left ventricular hypertrophy and cardiometabolic risk factors were assessed. The prevalence of peripheral arterial disease among subjects with resistant, uncontrolled and controlled hypertension was 6/37 (16%), 22/275 (8%) and 0/73 (0%), respectively (P=0.006). There were no differences in the prevalence of renal insufficiency, left ventricular hypertrophy or metabolic parameters between the groups. Resistant hypertension affects vasculature more than uncontrolled hypertension, and thus it can be regarded as a marker of more severe disease.

Baroreflex activation therapy for patients with drug-resistant hypertension

Uncontrolled or resistant hypertension is still a major problem facing many physicians daily in the clinic. Several new therapies are being developed to help those patients whose blood pressure does not respond sufficiently to regular antihypertensive medication. One of these promising therapies is electrical activation of the carotid sinus baroreflex. In this overview, the authors predominantly summarize the background, efficacy and safety of this promising treatment with its latest achievements in patients with resistant hypertension. The authors also discuss certain issues that need further clarification before this therapy can be added to the common treatment guidelines of hypertension.

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

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

Salt, the renin-angiotensin-aldosterone system and resistant hypertension

High salt intake is a risk for developing resistant hypertension, and even under triple therapy with diuretics, an angiotensin-converting enzyme inhibitor/angiotensin receptor blocker and a calcium channel blocker, the volume is occasionally not controlled. In such cases, a mineralocorticoid receptor (MR) antagonist additively lowers the circulating blood volume and blood pressure despite the lower circulating aldosterone level. This mechanism may be explained by the increase in the number of MR under some conditions or the activation of these receptors independent of aldosterone. Future diagnostic tools to evaluate receptor activity may be valuable for the proper diagnosis and choice of therapy. Additionally, basic research has suggested that oxidative stress and the renin-angiotensin-aldosterone system in the brain represent new targets for the treatment of resistant hypertension.

Vitamin D therapy to reduce blood pressure and left ventricular hypertrophy in resistant hypertension: randomized, controlled trial

Low 25-hydroxyvitamin D levels are associated with higher prevalent blood pressure. We tested whether high-dose intermittent oral vitamin D therapy could reduce blood pressure and left ventricular mass in patients with hypertension resistant to conventional treatment. We conducted a parallel-group, double-blind, randomized placebo-controlled trial. Patients with supine office blood pressure >140/90 mm Hg on ≥3 antihypertensive agents received 100 000 U oral vitamin D3 or matching placebo every 2 months. Office and 24-hour ambulatory blood pressure, glucose, and cholesterol were measured at baseline, 2, 4, and 6 months; left ventricular mass index was measured by cardiac MRI on a subgroup at baseline and 6 months. The primary outcome was mean 24-hour ambulatory blood pressure at 6 months. A total of 68 participants were randomized, 34 in each group. Mean age was 63 (SD 11) years, mean baseline office blood pressure was 154/84 (13/10) mm Hg, and mean baseline 25-hydroxyvitamin D level was 42 (16) nmol/L. Treatment with vitamin D did not reduce 24-hour ambulatory blood pressure (adjusted treatment effects: systolic, +3 mm Hg; 95% confidence interval, -4 to +11; P=0.33; diastolic, -2 mm Hg; 95% confidence interval, -6 to +2; P=0.29); similar results were seen for office blood pressure. Left ventricular mass index was measured in a subgroup (n=25); no reduction was seen with vitamin D treatment (adjusted treatment effect, +4 g/m(2); 95% confidence interval, 0 to +7; P=0.04). There was no significant change in cholesterol or glucose levels. Thus, 6 months of intermittent, high-dose oral vitamin D3 did not reduce blood pressure or left ventricular mass in patients with resistant hypertension.

Prevalence, predictors, and outcomes in treatment-resistant hypertension in patients with coronary disease

BACKGROUND

Increasingly, apparent treatment-resistant hypertension has been recognized. However, much of the prevalence, predictors, and outcomes are largely unknown, especially in patients with coronary artery disease.

METHODS

We evaluated 10,001 patients with coronary artery disease who were enrolled in the Treating to New Targets trial. Apparent treatment-resistant hypertension was defined as blood pressure ≥ 140 mm Hg despite 3 antihypertensive agents or <140 mm Hg with ≥ 4 antihypertensive agents. The primary outcome was major cardiovascular events (composite of fatal coronary heart disease, nonfatal myocardial infarction, resuscitated cardiac arrest, and stroke).

RESULTS

Among the 10,001 patients in the trial, 1112 (11.1%) had apparent treatment-resistant hypertension. In a multivariable model adjusting for baseline differences, the treatment-resistant hypertension group had a 64% increase in primary outcome (hazard ratio [HR], 1.64; 95% confidence interval [CI], 1.39-1.94; P < .001), driven by a 69% increase in coronary heart disease death (HR, 1.69; 95% CI, 1.22, 2.34; P = .001) and 73% increase in nonfatal myocardial infarction (HR, 1.73; 95% CI, 1.39-2.16, P < .0001) when compared with the no apparent treatment-resistant hypertension group. In addition, patients with apparent treatment-resistant hypertension had a 71% increase in major coronary event (P < .0001), 45% increase in death (P = .001), 33% increase in heart failure (P = .05), 53% increase in any cardiovascular event (P < .0001), 60% increase in any coronary event (P < .0001), 68% increase in angina (P < .0001), and 51% increase in coronary revascularization (P < .0001) when compared with the no apparent treatment-resistant hypertension group. Results were largely similar whether the definition of apparent treatment-resistant hypertension was based on a blood pressure ≥ 140 mm Hg despite 3 agents or a blood pressure <140 mm Hg with ≥ 4 agents.

CONCLUSIONS

In patients with coronary artery disease, apparent treatment-resistant hypertension is associated with a marked increase in the risk of cardiovascular morbidity and mortality, including an increase in all-cause death.

Refractory hypertension: determination of prevalence, risk factors, and comorbidities in a large, population-based cohort

Refractory hypertension is an extreme phenotype of antihypertensive treatment failure. Participants in the REasons for Geographic And Racial Differences in Stroke (REGARDS) Study, a large (n=30 239), population-based cohort were evaluated to determine the prevalence of refractory hypertension and associated cardiovascular risk factors and comorbidities. Refractory hypertension was defined as uncontrolled blood pressure (systolic/diastolic, ≥140/90 mm Hg) on ≥5 antihypertensive drug classes. Participants with resistant hypertension (systolic/diastolic, ≥140/90 mm Hg on ≥3 or <140/90 mm Hg on ≥4 antihypertensive classes) and all participants treated for hypertension served as comparator groups. Of 14 809 REGARDS participants receiving antihypertensive treatment, 78 (0.5%) had refractory hypertension. The prevalence of refractory hypertension was 3.6% among participants with resistant hypertension (n=2144) and 41.7% among participants on ≥5 antihypertensive drug classes. Among all participants with hypertension, black race, male sex, living in the stroke belt or buckle, higher body mass index, lower heart rate, reduced estimated glomerular filtration rate, albuminuria, diabetes mellitus, and history of stroke and coronary heart disease were associated with refractory hypertension. Compared with resistant hypertension, prevalence ratios for refractory hypertension were increased for blacks (3.00; 95% confidence interval, 1.68-5.37) and those with albuminuria (2.22; 95% confidence interval, 1.40-3.52) and diabetes mellitus (2.09; 95% confidence interval, 1.32-3.31). The median 10-year Framingham risk for coronary heart disease and stroke was higher among participants with refractory hypertension when compared with those with either comparator group. These data indicate that although resistant hypertension is relatively common among treated patients with hypertension, true antihypertensive treatment failure is rare.

Characteristics of resistant hypertension in a large, ethnically diverse hypertension population of an integrated health system

OBJECTIVE

To evaluate the prevalence of and characterize resistant hypertension in a large representative population with successful hypertension management and reliable health information.

PATIENT AND METHODS

We performed a cross-sectional study using clinical encounter, laboratory, and administrative information from the Kaiser Permanente Southern California health system between January 1, 2006, and December 31, 2007. From individuals older than 17 years with hypertension, resistant hypertension was identified and prevalence was determined. Multivariable logistic regression was used to calculate odds ratios (ORs), with adjustments for demographic characteristics, clinical variables, and medication use.

RESULTS

Of 470,386 hypertensive individuals, 60,327 (12.8%) were identified as having resistant disease, representing 15.3% of those taking medications. Overall, 37,061 patients (7.9%) had uncontrolled hypertension while taking 3 or more medicines. The ORs (95% CIs) for resistant hypertension were greater for black race (1.68 [1.62-1.75]), older age (1.11 [1.10-1.11] for every 5-year increase), male sex (1.06 [1.03-1.10]), and obesity (1.46 [1.42-1.51]). Medication adherence rates were higher in those with resistant hypertension (93% vs 89.8%; P<.001). Chronic kidney disease (OR, 1.84; 95% CI, 1.78-1.90), diabetes mellitus (OR, 1.58; 95% CI, 1.53-1.63), and cardiovascular disease (OR, 1.34; 95% CI, 1.30-1.39) were also associated with higher risk of resistant hypertension.

CONCLUSION

In a more standardized hypertension treatment environment, we observed a rate of resistant hypertension comparable with that of previous studies using more fragmented data sources. Past observations have been limited due to nonrepresentative populations, reliability of the data, heterogeneity of the treatment environments, and less than ideal control rates. This cohort, which was established using an electronic medical record-based approach, has the potential to provide a better understanding of resistant hypertension and outcomes.

Prevalence and risk factors for resistant hypertension among hypertensive patients from a developing country

Background

To study the prevalence and define deferential risk factors for ‘Resistant’ hypertension (RHT) in a hypertensive population of South Asian origin.

Methods

A descriptive cross-sectional study was carried out among hypertensive patients attending clinics at the Cardiology Unit, Colombo from July-October 2009. All the patients with hypertension who provided informed written consent were recruited to the study (n = 277). A pre-tested interviewer-administered questionnaire was used for data collection. A binary logistic-regression analysis was performed in all patients with ‘presence of RHT’ as the dichotomous dependent variable and other independent co-variants.

Results

Mean age was 61 ± 10.3 years and 50.2% were males. The mean of average systolic and diastolic blood pressures (BP) were 133.04 ± 12.91 mmHg and 81.07 ± 6.41 mmHg respectively. Uncontrolled BP was present in 41.1% (n = 114) of patients, of which RHT was present in 19.1% (n = 53). Uncontrolled BP were due to ‘therapeutic inertia’ in 27.8% of the study population. Those with diabetes mellitus, obesity (BMI > 27.5 kg/m²) and those who were older than 55 years were significantly higher in the RHT group than in the non-RHT group. In the binary logistic regression analysis older age (OR:1.36), longer duration of hypertension (OR:1.76), presence of diabetes mellitus (OR:1.67) and being obese (OR:1.84) were significantly associated with RHT.

Conclusion

A significant proportion of the hypertensive patients were having uncontrolled hypertension. Nearly 1/5^th of the population was suffering from RHT, which was significantly associated with the presence of obesity and diabetes mellitus. Therapeutic inertia seems to contribute significantly towards the presence of uncontrolled BP.

Urinary albumin excretion at follow-up predicts cardiovascular outcomes in subjects with resistant hypertension

BACKGROUND

Renal function and albuminuria predict cardiovascular disease (CVD) in general population. However, their prognostic value in patients with resistant hypertension (RH) is somewhat unknown.

OBJECTIVE

To determine the ability of renal function and albuminuria to predict CVD in RH patients.

METHODS

One hundred and thirty-three RH (blood pressure [BP] ≥140/90mmHg despite treatment with ≥3 drugs) patients were evaluated. Median follow-up was 73 months. Primary endpoint was a composite of non-fatal cardiovascular events or cardiovascular death. Serum creatinine (SCr) and estimated glomerular filtration rate (eGFR) were determined. Microalbuminuria was defined as a urinary albumin-to-creatinine ratio (UACR) ≥30mg/g.

RESULTS

Twenty-two patients (16.5%) reached the primary endpoint. Long-term elevated UACR (66 vs. 17mg/g, P=0.045), but not at baseline, was associated with the primary endpoint, after adjusting for age, prior CVD, and both eGFR and office systolic-BP at baseline and during follow-up. Although baseline SCr and eGFR were associated with CVD, significance was lost after baseline risk adjustment. Baseline microalbuminuria prevalence was 45% and 41% in patients with and without CVD (P=0.813), while percentages of patients with microalbuminuria at follow-up were 67% and 28%, respectively (P=0.002). More patients with de novo CVD, compared with those without CVD, developed microalbuminuria at follow-up (28% vs. 6%) or had persistent microalbuminuria (39% vs. 21%), while fewer patients with CVD had microalbuminuria regression (11% vs. 19%) or remained normoalbuminurics (22% vs. 53%; overall P=0.005).

CONCLUSION

In RH patients, the inability to microalbuminuria regression, either due to persistence or new appearance, independently predicts CVD.

Resistant hypertension? Assessment of adherence by toxicological urine analysis

OBJECTIVE

Uncontrolled hypertension under antihypertensive multidrug regimen is not necessarily always true resistance. Incomplete adherence is one of several possible causes of uncontrolled hypertension. Nonadherence remains largely unrecognized and is falsely interpreted as treatment resistance, as it is difficult to confirm or exclude objectively. This is the first study assessing adherence in patients with apparent resistant hypertension systematically via toxicological urine screening.

METHODS

All patients referred from primary care physicians because of uncontrolled hypertension between 2004 and 2011 were analysed. Adherence was assessed in all patients with uncontrolled hypertension despite the concurrent use of at least four antihypertensive agents by using liquid chromatography-mass spectrometry analysis for antihypertensive drugs or their corresponding metabolites in urine.

RESULTS

A total of 375 patients with uncontrolled hypertension were referred. After optimization of drug therapy and exclusion of white coat hypertension, 108 patients met criteria for resistant hypertension. Of those, 15 patients had secondary causes of hypertension and 17 achieved goal blood pressure with quadruple antihypertensive therapy. Of the remaining 76 patients, 40 patients (53%) were found to be nonadherent. Among nonadherent patients, 30% had complete and 70% had incomplete adherence; 85% of the latter had taken less than 50% of drugs prescribed. Lack of adherence was almost evenly distributed between different classes of antihypertensive drugs.

CONCLUSION

Low adherence was the most common cause of poor blood pressure control in patients with apparent resistant hypertension, being twice as frequent as secondary causes of hypertension. Incomplete adherence was far more common than complete nonadherence; thus, assessment of adherence in patients on multiple drug regime is only reliable when all drugs are included in assessment. Assessing adherence by toxicological urine screening is a useful tool in detecting low adherence, especially in the setting of multidrug regimen as a cause of apparently resistant hypertension.

Resistant hypertension: patient characteristics, risk factors, co-morbidities and outcomes

Among the vast population of hypertensive subjects, between 10 and 15% do not achieve an adequate blood pressure (BP) control despite the use of at least three antihypertensive agents. This group, designated as having resistant hypertension (RH), represents one of the most important clinical challenges in hypertension evaluation and management. Resistant hypertensives are characterized by several clinical particularities, such as a longer history of hypertension, obesity and other accompanying factors, such as diabetes, left ventricular hypertrophy, albuminuria and renal dysfunction. In addition to other diagnostic and therapeutic maneuvers, such as excluding secondary hypertension, ensuring treatment adherence and optimizing therapeutic schemes, ambulatory BP monitoring (ABPM) is crucial in the clinical evaluation of patients with RH. ABPM distinguish between those with out-of-office BP elevation (true resistant hypertensives) and those having white-coat RH (WCRH; normalcy of 24-h BPs), the prevalence of the latter estimated in about one-third of the population with RH. True resistant hypertensives also exhibit more frequently other co-morbidities, more severe target organ damage and a worse cardiovascular prognosis, in comparison to those with WCRH. Some device-based therapies have recently been developed for treatment of RH. This requires a better characterization of a potential candidate population. A better knowledge of the clinical features of resistant hypertensive subjects, the confirmation of elevated BP values out of the doctor's office, and improvements in the search for secondary causes would help to select those candidates for newer therapies, once the pharmacological possibilities have been exhausted.

Characteristics, drug combinations and dosages of primary care patients with uncontrolled ambulatory blood pressure and high medication adherence

Most studies on the prevalence and determinants of resistant hypertension (RH) do not account for white coat hypertension, medication non-adherence, or use of suboptimal treatment dosages. We studied the characteristics, drug combinations, and dosages of patients on at least three antihypertensives of different classes who had uncontrolled blood pressure on 24-hour ambulatory blood pressure monitoring and high medication adherence measured by electronic monitoring. The data were collected as part of the baseline measures of a hypertension control trial. Of 140 monitored primary care patients, all with uncontrolled office blood pressure, 69 (49%) were on at least three antihypertensives of different classes. Of these 69, 15 (22%) were controlled on ambulatory blood pressure monitoring, 20 (29%) were uncontrolled and non-adherent, leaving only 34 (49%) adherent to their medications and having uncontrolled ambulatory hypertension (uncontrolled RH). Thirty-one (91%) of the 34 uncontrolled RH patients were prescribed a diuretic, of which 24 were on hydrochlorothiazide 25 mg. Less than half of the patients on angiotensin-converting enzyme inhibitor, angiotensin receptor blocker, or calcium channel blocker were prescribed maximal doses of these agents. Half of the RH can be attributed to white coat effect and poor medication adherence, and all of the remaining patients were on apparently suboptimal drug combinations and/or dosages. Primary care physicians need to be educated regarding the optimal treatment of RH.

Clinical situations associated with difficult-to-control hypertension

There is no doubt that patients with high blood pressure (BP) are at higher cardiovascular and death risk than those subjects whose BP levels are below the admitted normal threshold. However, most of the epidemiological surveys show that BP is uncontrolled in more than fifty percent of hypertensive subjects. There are several reasons that can justify this lack of hypertension control, some of them depending on the patient, such as therapeutic adherence, or some related to the doctor, due to therapeutic inertia or reluctance to increment the number and doses of antihypertensive drugs. Sometimes the efficacy or adverse effects related to the antihypertensive drugs underlie the uncontrolled hypertension. And, finally, there are some clinical conditions that are associated with difficult-to-control hypertension. Among them, comorbidities such as diabetes, obesity, obstructive sleep apnoea syndrome or chronic kidney disease, but also drug-related hypertension or resistant hypertension. In this article we review the epidemiology and the conditions which are related to poorly controlled hypertension and that can explain why hypertension may become difficult-to-treat.

Identifying patients with resistant hypertension and options for clinical management

In addition to the increasing prevalence of hypertension, the number of patients with treatment-resistant hypertension is also rising. It is important to identify these patients in order to improve the treatment outcomes and to screen for potential secondary causes. Clinical characteristics of patients with resistant hypertension include advanced age, male gender, obesity, high salt intake and alcohol consumption. Those with high baseline blood pressure, diabetes, chronic kidney disease or obstructive sleep apnea are also prone to developing resistant hypertension. Physicians should initiate close monitoring and aggressive treatment for those patients, as resistant hypertension is associated with a higher risk of cardiovascular morbidities, regardless of the control of blood pressure. However, treatment of resistant hypertension is currently a great challenge in clinical practice as all of these patients are already taking multiple antihypertensive medications, including the first-line treatments advocated in guidelines. In patients who have been presented multiple drugs, the room for further titration is often limited. Spironolactone has been demonstrated to be effective as an add-on therapy for patients with resistant hypertension. In addition to drug treatment, baroreceptor stimulation therapy and renal sympathetic denervation are promising new approaches in this group of patients. Further studies on the pathogenesis and the treatment of resistant hypertension would help to improve the outcome of this patient subgroup.

Resistant hypertension and target organ damage

Cardiovascular (CV) complications such as myocardial infarction, heart failure, stroke and renal failure are related to both the degree and the duration of blood pressure (BP) increase. Resistant hypertension (RH) is associated with a higher risk of CV complications and a higher prevalence of target organ damage (TOD). The relationship between CV disease and TOD can be bidirectional. Elevated BP in RH may cause CV structural and functional alterations, and the development or persistence of left ventricular hypertrophy, aortic stiffness, atherosclerotic plaques, microvascular disease and renal dysfunction, may render hypertension more difficult to control. Specifically, RH is related to several conditions, including obesity, sleep apnea, diabetes, metabolic syndrome and hyperaldosteronism, characterized by an overexpression of humoral and hormonal factors that are involved in the development and maintenance of TOD. Optimal therapeutic strategies, including pharmacological treatment and innovative invasive methodologies, have been shown to achieve adequate BP control and induce the regression of TOD, thereby potentially improving patient prognosis.

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.