Tanja Dudenbostel

REFRACTORY HYPERTENSION: DEFINITION, PREVALENCE AND PATIENT CHARACTERISTICS

J Clin Hypertens (Greenwich).

Effects of antihypertensive drugs on arterial stiffness.

In this review, we discuss the possible pathophysiological mechanisms and the role of arterial stiffness as a biomarker, a blood pressure–independent predictor of cardiovascular morbidity and mortality. The effects of different antihypertensive drug classes on noninvasively assessed markers of arterial stiffness are also discussed. Current evidence will be reviewed regarding the effect of drugs on arterial stiffness, including the peripheral and central effects of angiotensin-converting enzyme inhibitors, angiotensin receptor antagonists, dihydropyridine calcium channel blockers, beta blockers (including vasodilating beta blockers), diuretics, and mineralocorticoid antagonists.

REFRACTORY HYPERTENSION: EVIDENCE OF HEIGHTENED SYMPATHETIC ACTIVITY AS A CAUSE OF ANTIHYPERTENSIVE TREATMENT FAILURE

Refractory hypertension is an extreme phenotype of treatment failure defined as uncontrolled blood pressure in spite of ≥5 classes of antihypertensive agents, including chlorthalidone and a mineralocorticoid receptor antagonist. A prospective evaluation of possible mechanisms of refractory hypertension has not been done. The goal of this study was to test for evidence of heightened sympathetic tone as indicated by 24-hour urinary normetanephrine levels, clinic and ambulatory heart rate (HR), HR variability, arterial stiffness as indexed by pulse wave velocity, and systemic vascular resistance compared with patients with controlled resistant hypertension. Forty-four consecutive patients, 15 with refractory and 29 with controlled resistant hypertension, were evaluated prospectively. Refractory hypertensive patients were younger (48±13.3 versus 56.5±14.1 years; P=0.038) and more likely women (80.0 versus 51.9%; P=0.047) compared with patients with controlled resistant hypertension. They also had higher urinary normetanephrine levels (464.4±250.2 versus 309.8±147.6 µg per 24 hours; P=0.03), higher clinic HR (77.8±7.7 versus 68.8±7.6 bpm; P=0.001) and 24-hour ambulatory HR (77.8±7.7 versus 68.8±7.6; P=0.0018), higher pulse wave velocity (11.8±2.2 versus 9.4±1.5 m/s; P=0.009), reduced HR variability (4.48 versus 6.11; P=0.03), and higher systemic vascular resistance (3795±1753 versus 2382±349 dyne·s·cm5·m2; P=0.008). These findings are consistent with heightened sympathetic tone being a major contributor to antihypertensive treatment failure and highlight the need for effective sympatholytic therapies in patients with refractory hypertension.Refractory hypertension is an extreme phenotype of treatment failure defined as uncontrolled blood pressure in spite of ≥5 classes of antihypertensive agents, including chlorthalidone and a mineralocorticoid receptor antagonist. A prospective evaluation of possible mechanisms of refractory hypertension has not been done. The goal of this study was to test for evidence of heightened sympathetic tone as indicated by 24-hour urinary normetanephrine levels, clinic and ambulatory heart rate (HR), HR variability, arterial stiffness as indexed by pulse wave velocity, and systemic vascular resistance compared with patients with controlled resistant hypertension. Forty-four consecutive patients, 15 with refractory and 29 with controlled resistant hypertension, were evaluated prospectively. Refractory hypertensive patients were younger (48±13.3 versus 56.5±14.1 years; P =0.038) and more likely women (80.0 versus 51.9%; P =0.047) compared with patients with controlled resistant hypertension. They also had higher urinary normetanephrine levels (464.4±250.2 versus 309.8±147.6 µg per 24 hours; P =0.03), higher clinic HR (77.8±7.7 versus 68.8±7.6 bpm; P =0.001) and 24-hour ambulatory HR (77.8±7.7 versus 68.8±7.6; P =0.0018), higher pulse wave velocity (11.8±2.2 versus 9.4±1.5 m/s; P =0.009), reduced HR variability (4.48 versus 6.11; P =0.03), and higher systemic vascular resistance (3795±1753 versus 2382±349 dyne·s·cm5·m2; P =0.008). These findings are consistent with heightened sympathetic tone being a major contributor to antihypertensive treatment failure and highlight the need for effective sympatholytic therapies in patients with refractory hypertension. # Novelty and Significance {#article-title-44}

Management of patients with resistant hypertension: current treatment options.

Resistant hypertension (RHTN) is an increasingly common clinical problem that is often heterogeneous in etiology, risk factors, and comorbidities. It is defined as uncontrolled blood pressure on optimal doses of three antihypertensive agents, ideally one being a diuretic. The definition also includes controlled hypertension with use of four or more antihypertensive agents. Recent observational studies have advanced the characterization of patients with RHTN. Patients with RHTN have higher rates of cardiovascular events and mortality compared with patients with more easily controlled hypertension. Secondary causes of hypertension, including obstructive sleep apnea, primary aldosteronism, renovascular disease, are common in patients with RHTN and often coexist in the same patient. In addition, RHTN is often complicated by metabolic abnormalities. Patients with RHTN require a thorough evaluation to confirm the diagnosis and optimize treatment, which typically includes a combination of lifestyle adjustments, and pharmacologic and interventional treatment. Combination therapy including a diuretic, a long-acting calcium channel blocker, an angiotensin-converting enzyme inhibitor, a beta blocker, and a mineralocorticoid receptor antagonist where warranted is the classic regimen for patients with treatment-resistant hypertension. Mineralocorticoid receptor antagonists like spironolactone or eplerenone have been shown to be efficacious in patients with RHTN, heart failure, chronic kidney disease, and primary aldosteronism. Novel interventional therapies, including baroreflex activation and renal denervation, have shown that both of these methods may be used to lower blood pressure safely, thereby providing exciting and promising new options to treat RHTN.

Resistant and Refractory Hypertension: Antihypertensive Treatment Resistance vs Treatment Failure.

Resistant or difficult to treat hypertension is defined as high blood pressure that remains uncontrolled with 3 or more different antihypertensive medications, including a diuretic. Recent definitions also include controlled blood pressure with use of 4 or more medications as also being resistant to treatment. Recently, refractory hypertension, an extreme phenotype of antihypertensive treatment failure has been defined as hypertension uncontrolled with use of 5 or more antihypertensive agents, including a long-acting thiazide diuretic and a mineralocorticoid receptor antagonist. Patients with resistant vs refractory hypertension share similar characteristics and comorbidities, including obesity, African American race, female sex, diabetes, coronary heart disease, chronic kidney disease, and obstructive sleep apnea. Patients with refractory vs resistant hypertension tend to be younger and are more likely to have been diagnosed with congestive heart failure. Refractory hypertension might also differ from resistant hypertension in terms of underlying cause. Preliminary evidence suggests that refractory hypertension is more likely to be neurogenic in etiology (ie, heightened sympathetic tone), vs a volume-dependent hypertension that is more characteristic of resistant hypertension in general.

Use of Aldosterone Antagonists for Treatment of Uncontrolled Resistant Hypertension

BACKGROUND Multiple studies indicate that primary aldosteronism (PA) is common in patients with resistant hypertension, with an estimated prevalence of approximately 20%. Additional studies suggest that beyond this 20% of patients with classical PA, there is a larger proportion of patients with lesser degrees of hyperaldosteronism which contributes even more broadly to antihypertensive treatment resistance. Given these observations, it is intuitive that use of aldosterone antagonists will provide antihypertensive benefit in patients with resistant hypertension and evidence of aldosterone excess. Intriguingly, however, are clinical findings demonstrating substantive benefit of aldosterone antagonists in patients with resistant hypertension, but without demonstrative evidence of hyperaldosteronism, that is, with seemingly normal or even low aldosterone levels. CONCLUSION Spironolactone is clearly established as the most effective fourth agent for treatment of uncontrolled resistant hypertension. Emerging observations suggest a further role of spironolactone for counteracting the effects of diet high in sodium, particularly in obese, hypertensive patients.

Refractory Hypertension: A Novel Phenotype of Antihypertensive Treatment Failure

The term resistant hypertension has been used since the early 1960s to identify patients with difficult-to-treat hypertension, meaning mostly, resistance to pharmacological therapy.1 In the 5 decades since the term was seemingly first applied, resistant hypertension has been consistently defined as failure to control high blood pressure despite of use of ≥3 antihypertensive agents of different classes, including a diuretic.2–5 The 2008 American Heart Association Scientific Statement on resistant hypertension included in its definition patients whose blood pressure had been uncontrolled with 3 medications, but controlled with ≥4 medications.4 Although the number of medications required to satisfy the definition is arbitrary, the purpose of creating a category of resistant hypertension is to identify patients who, because of the difficulty in controlling their blood pressure, may benefit from special diagnostic and therapeutic considerations, including referral to a hypertension specialist. Having an agreed on definition that can be reliably applied to different cohorts has also facilitated research for this subgroup of patients, including identification of risk factors and underlying mechanisms, assessing outcomes and developing targeted treatments. The term refractory hypertension has often been used interchangeably with resistant hypertension to also refer to patients with difficult-to-treat hypertension.1–3,5 However, based on the number of respective PubMed citations resistant hypertension has been used much more often than refractory hypertension to indicate patients with hypertension resistant to pharmacological treatment. Recently, the term refractory hypertension has been applied to a small group of patients who are truly refractory to treatment, that is, patients who fail to achieve target blood pressure on maximal antihypertensive therapy.6 Determining whether such patients simply represent extreme cases of resistant hypertension or a novel phenotype in terms of risk and cause has been the focus of initial attempts to define and characterize …

Body Mass Index Predicts 24-Hour Urinary Aldosterone Levels in Patients With Resistant Hypertension

Prospective studies indicate that hyperaldosteronism is found in 20% of patients with resistant hypertension. A small number of observational studies in normotensive and hypertensive patients suggest a correlation between aldosterone levels and obesity while others could not confirm these findings. The correlation between aldosterone levels and body mass index (BMI) in patients with resistant hypertension has not been previously investigated. Our objective was to determine whether BMI is positively correlated with plasma aldosterone concentration, plasma renin activity, aldosterone:renin ratio, and 24-hour urinary aldosterone in black and white patients. We performed a cross-sectional analysis of a large diverse cohort (n=2170) with resistant hypertension. The relationship between plasma aldosterone concentration, plasma renin activity, aldosterone:renin ratio, 24-hour urinary aldosterone, and BMI was investigated for the entire cohort, by sex and race (65.3% white, 40.3% men). We demonstrate that plasma aldosterone concentration and aldosterone:renin ratio were significantly correlated to BMI (P<0.0001) across the first 3 quartiles, but not from the 3rd to 4th quartile of BMI. Plasma renin activity was not correlated with BMI. Twenty-four–hour urinary aldosterone was positively correlated across all quartiles of BMI for the cohort (P<0.0001) and when analyzed by sex (men P<0.0001; women P=0.0013) and race (P<0.05), and stronger for men compared with women (r=0.19, P<0.001 versus r=0.05, P=0.431, P=0.028) regardless of race. In both black and white patients, aldosterone levels were positively correlated to increasing BMI, with the correlation being more pronounced in black and white men. These findings suggest that obesity, particularly the abdominal obesity typical of men, contributes to excess aldosterone in patients with resistant hypertension.

Serum 25-hydroxyvitamin D and Ethnic Differences in Arterial Stiffness and Endothelial Function

Background Vitamin D reportedly influences vascular function, which is worse in African Americans (AAs) relative to European Americans (EAs). It is not clear if ethnic differences in 25(OH)D mediate differences in vascular function. This study examined the relationships of serum 25-hydroxyvitamin D (25(OH)D) with indicators of vascular function among healthy, young AA and EA adults. Methods This is a cross sectional study involving 23 AAs and 22 EAs. The main outcomes were augmentation index (AIx75), central aortic pressure, pulse wave velocity (PWV), flow-mediated dilation (FMD), and seated and supine blood pressures. Results Results indicated that 25(OH)D was inversely associated with AIx75, supine systolic blood pressure (SBP), central aortic SBP and central aortic diastolic blood pressure (DBP), independent of age, sex, and percent body fat (standardized β= -0.29 to -0.43, P < 0.05 for all). AAs had greater AIx75 (P = 0.04) and PWV (P = 0.07) and lower FMD (P = 0.02) compared to EA after adjusting for age and percent body fat; further adjustment for 25(OH)D reduced the ethnic differences (P = 0.44, 0.53, and 0.20, respectively). Conclusion The 25(OH)D was associated with vascular function in healthy adults, and lower 25(OH)D among AAs may contribute to their greater arterial stiffness and reduced endothelial function (Clinical trials.gov NCT01041365, NCT01041547).

Associations between Vascular Health Indices and Serum Total, Free and Bioavailable 25-Hydroxyvitamin D in Adolescents

Objective The role of vitamin D in cardiovascular health remains debated as results have been inconsistent. Previous studies have not considered the bioavailability of 25-hydroxy vitamin D [25(OH)D]. Objectives of our study were to investigate the association between serum concentrations of total, free and bioavailable 25(OH)D and independent predictors of cardiovascular risk such as flow mediated dilatation (FMD) and augmentation index (AIx). Design This cross-sectional study included 47 post-menarchal, adolescent females [31 African American (AA) and 16 European American (EA)]. Methods AIx was standardized to a heart rate of 75 beats/min (AIx75). Free and bioavailable 25(OH)D concentrations were calculated from standard formulas. Results and Conclusions Mean age of the participants was 15.8±1.4 years and mean body mass index was 23.1±4.0 kg/m2. Serum total 25(OH)D was not associated with FMD, but was positively associated with AIx75 in the adjusted model (rho = 0.4, P = 0.03). AIx75 was positively associated with bioavailable 25(OH)D (rho = 0.4, P = 0.004) and free 25(OH)D (rho = 0.4, P = 0.009) and the associations persisted after adjusting for covariates. In race-specific analyses, total, free and bioavailable 25(OH)D were strongly positively associated with AIx75 in AA (rho = 0.5, 0.4, 0.4, respectively), which persisted even after adjusting for covariates. Whereas in EA there was an inverse association between total 25(OH)D and AIx75 in EA (rho = −0.6), which attenuated after adjusting for covariates. Conclusion Circulating total, free and bioavailable 25(OH)D were associated with arterial stiffness in adolescent girls, and these associations were race dependent. Notwithstanding, the implications of associations between vascular function indices and 25(OH)D remains unclear.