Influence of race and dietary salt on the antihypertensive efficacy of an angiotensin-converting enzyme inhibitor or a calcium channel antagonist in salt-sensitive hypertensives

Role of diet in hypertension management

The prevalence of hypertension is high and increasing worldwide. Drug therapy is effective, but for both "prehypertensive" and treated hypertensive patients, lifestyle changes are also important. Dietary modification is a key part of these changes, although skepticism about the role of diet in determining blood pressure has slowed implementation of the available guidelines. However, there is now a large body of evidence supporting a role for dietary salt, potassium, alcohol, and body mass in determining blood pressure. Studies such as PREMIER have shown that salt restriction (<6 g/d), alcohol moderation (<2U/d in men and <1U/d in women), weight loss (if BMI>25), exercise, and a DASH (Dietary Approaches to Stop Hypertension) diet (supplying 20-30 mmol/d of potassium) can achieve decreases in systolic blood pressure of approximately 10 to 15 mm Hg when applied together. Of the dietary changes, salt intake remains the most amenable to change. But we must further reduce salt in processed food if it is to be part of a wider strategy to lower blood pressure in the general population. Nevertheless, the message to patients must be that dietary changes made within a concerted alteration in lifestyle can have a very significant impact on their blood pressure.

Salt intake and progression of chronic kidney disease: An overlooked modifiable exposure? A commentary

The relationship between sodium chloride (salt) intake and blood pressure and cardiovascular disease has been debated for decades. Overlooked is whether there is a relationship between dietary electrolyte ingestion (both sodium and potassium) and risk for progression of kidney disease, particularly in patients who manifest early evidence of chronic kidney disease (CKD). Patients with CKD often are salt sensitive and respond to increased ingestion of sodium chloride with increased blood pressure. Of concern is the clinical evidence that salt-sensitive patients respond to increased salt intake, in the physiological range, with increased glomerular filtration fraction and proteinuria. Thus, these salt-induced changes in both systemic blood pressure and the renal microcirculation create a favorable theoretical scenario for progressive renal injury. Increased salt intake also attenuates the antihypertensive effects of most antihypertensive drugs. Consequently, salt intake must be considered a potential modifiable risk factor for the progression of kidney disease.

Use of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in high-risk clinical and ethnic groups with diabetes

BACKGROUND

Diabetes causes 45% of incident end-stage renal disease (ESRD). Risk of progression is higher in those with clinical risk factors (albuminuria and hypertension), and in ethnic minorities (including blacks, Asians, and Latinos). Angiotensin-converting enzyme inhibitors (ACE) and angiotensin receptor blockers (ARB) slow the progression of diabetic nephropathy, yet little is known about their use among patients at high risk for progression to ESRD.

OBJECTIVES

To examine the prevalence of ACE or ARB (ACE/ARB) use overall and within patients with high-risk clinical indications, and to assess for ethnic disparities in ACE/ARB use.

DESIGN

Observational cohort study.

SETTING

Kaiser Permanente Northern California (KPNC) Diabetes Registry, a longitudinal registry that monitors quality and outcomes of care for all KPNC patients with diabetes.

PATIENTS

Individuals (N= 38887) with diabetes who were continuously enrolled with pharmacy benefits during the year 2000, and had self-reported ethnicity data on survey.

INTERVENTIONS AND MEASUREMENTS

Pharmacy dispensing of ACE/ARB.

RESULTS

Forty-one percent of the cohort had both hypertension and albuminuria, 30% had hypertension alone, and 12% had albuminuria alone. Fourteen percent were black, 11% Latino, 13% Asian, and 63% non-Latino white. Overall, 61% of the cohort received an ACE/ARB. ACE/ARB was dispensed to 74% of patients with both hypertension and albuminuria, 64% of those with hypertension alone, and 54% of those with albuminuria alone. ACE/ARB was dispensed to 61% of whites, 63% of blacks, 59% of Latinos, and 60% of Asians. Among those with albuminuria alone, blacks were significantly (P =.0002) less likely than whites to receive ACE/ARB (47% vs 56%, respectively). No other ethnic disparities were found.

CONCLUSIONS

In this cohort, the majority of eligible patients received indicated ACE/ARB therapy in 2000. However, up to 45% to 55% of high-risk clinical groups (most notably individuals with isolated albuminuria) were not receiving indicated therapy. Additional targeted efforts to increase use of ACE/ARB could improve quality of care and reduce ESRD incidence, both overall and in high-risk ethnic groups. Policymakers might consider use of ACE/ARB for inclusion in diabetes performance measurement sets.

Gender difference in the response to an angiotensin-converting enzyme inhibitor and a diuretic in hypertensive patients of African descent

BACKGROUND

The efficacy of angiotensin-converting enzyme (ACE) inhibitors in decreasing blood pressure in African patients is controversial.

OBJECTIVE

We examined the ambulatory blood pressure (ABP) response to a diuretic and an ACE inhibitor in hypertensive patients of East African descent and evaluated the individual characteristics that determined treatment efficacy.

DESIGN

A single-blind randomized AB/BA crossover design.

SETTING

Hypertensive families of East African descent from the general population in the Seychelles.

PARTICIPANTS

Fifty-two (29 men and 23 women) out of 62 eligible hypertensive patients were included.Main outcome measures ABP response to 20 mg lisinopril (LIS) daily and 25 mg hydrochlorothiazide (HCT) daily given for a 4-week period. Results The daytime systolic/diastolic ABP response to HCT was 4.9 [95% confidence interval (CI) 1.2-8.6]/3.6 (1.0-6.2) mmHg for men and 12.9 (9.2-16.6)/6.3 (3.7-8.8) mmHg for women. With LIS the response was 18.8 (15.0-22.5)/14.6 (12.0-17.1) mmHg for men and 12.4 (8.7-16.2)/7.7 (5.1-10.2) mmHg for women. The night-time systolic/diastolic response to HCT was 5.0 (0.6-9.4)/2.7 [(-0.4)-5.7] mmHg for men and 11.5 (7.1-16.0)/5.7 (2.6-8.8) mmHg for women, and to LIS was 18.7 (14.2-22.1)/15.4 (12.4-18.5) mmHg for men and 3.5 [(-1.0)-7.9]/2.3 [(-0.8)-5.4] mmHg for women. Linear regression analyses showed that gender is an independent predictor of the ABP responses to HCT and to LIS.

CONCLUSIONS

Hypertensive patients of African descent responded better to LIS than to HCT. Men responded better to LIS than to HCT and women responded similarly to both drugs.

Salt handling and hypertension

The kidney plays a central role in our ability to maintain appropriate sodium balance, which is critical to determination of blood pressure. In this review we outline current knowledge of renal salt handling at the molecular level, and, given that Westernized societies consume more salt than is required for normal physiology, we examine evidence that the lowering of salt intake can combat hypertension.

Hypertension therapy: mixing, matching, and meeting targets

The inappropriate control of hypertension is a public health problem worldwide. It is notable that although there are several causes for this situation, lack of effective pharmacotherapy is not among them. It has long been known that combinations of antihypertensive drugs are highly effective in most patients; the problem is implementing treatment recommendation guidelines into clinical practice with the most effective and best tolerated therapies. The latest guidelines on therapies for hypertension from the World Health Organization/International Society of Hypertension, the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (US), and the European Societies of Hypertension and Cardiology consistently emphasize this need of combination treatments in a large part of the hypertensive patient population. This review focuses on the combination of one of the oldest drugs, thiazide diuretics, with one of the youngest, angiotensin-receptor blockers, and analyzes the available literature regarding potential applications in specific populations. This represents one of the most widely used, rational and effective combination therapies, combining excellent control of blood pressure with unequalled tolerability. In addition, angiotensin-receptor blocker/diuretic combinations may have cardiovascular benefits beyond those from blood pressure lowering itself.

Pharmacological strategies for kidney function preservation: are there differences by ethnicity?

The prevalence of chronic kidney disease (CKD) is on the rise in all ethnic groups. This is because of the increased prevalence of obesity, diabetes mellitus, the metabolic syndrome, and the inadequate control of elevated blood pressure and other cardiovascular-renal risk factors, especially in ethnic minority populations. The implications of the aforementioned trends in risk factor prevalence and control are profound. Moreover, these trends negatively impact patient quality of life and place an enormous financial burden on the health care system for the provision of care to patients with CKD, end-stage renal disease (ESRD), and/or cardiovascular disease (CVD). Thus, it is of utmost importance to devise strategies that prevent kidney disease and delay progressive loss of kidney function in persons with CKD. Proven strategies include pharmacological interventions that lower blood pressure to less than target levels (<130/80 mm Hg), attainment of optimal glycemic control (Hb A1c <7%), and reducing urinary protein excretion. It is also possible, although yet unproven, that correction of anemia and aggressive treatment of dyslipidemia may forestall the loss of kidney function. In general, ethnic minorities are underrepresented in most large trials. Recently, a few outcome clinical trials in blacks have reinforced the lessons of kidney function preservation already learned in nonblack populations. That is, the reversible risk factors for CKD appear to be virtually identical and, at least in nondiabetic CKD, pharmacological targeting of the renin-angiotensin-aldosterone system (RAAS) with angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers preserves kidney function better than non-RAAS blood pressure-lowering regimens, especially when significant proteinuria exists. Although more CKD studies in ethnic minorities are needed, until they become available, the best available evidence from the existing clinical trial database should be applied to minorities with CKD-even when specific data are not available for a specific racial or ethnic group. Why this approach? First, there are no known unique risk factors for kidney disease in any ethnic group. Second, poor control of reversible risk factors for CKD is universal, particularly in blacks and other ethnic minorities. Thus, it is logical to predict that more efficient use of strategies proven to forestall loss of kidney function will reduce the excess of CKD and ESRD in ethnic minorities relative to non-minority populations. However, medical-based strategies alone are probably not enough. The global epidemic of obesity will fuel the growing population of persons, especially among ethnic minorities, with diabetes, the main cause of CKD, ESRD, and CVD. The obesity and diabetes epidemics are unlikely to abate without innovative and ultimately effective public health approaches.

Antecedents to effective treatment of hypertension in Hispanic populations

Hypertension is a common medical disorder affecting >50 million people. It is a primary modifiable risk factor to cardiovascular disease and a leading cause of death in black and Hispanic groups. This article focuses on patient-specific and physician-specific barriers that contribute to underdiagnosis, undertreatment, access issues, and poor adherence to therapy. Two cross-cultural interviewing frameworks, ETHNIC and ADHERE, are discussed as approaches that complement the traditional clinical assessment and treatment of hypertension in Hispanics.

Rationale for combination therapy as initial treatment for hypertension

Recent hypertension guidelines recommend initiating antihypertensive therapy with a combination of two or more agents in patients whose blood pressure exceeds their appropriate blood pressure goal by 20/10 mm Hg. This recommendation is based on the knowledge that the majority of patients with blood pressures of this magnitude will not achieve sufficient blood pressure reduction with monotherapy. Further, compared with high-dose monotherapy, combination therapy is often associated with fewer adverse effects and, for this reason, may improve patient adherence. Bringing patients to blood pressure goal quickly is likely to improve clinical outcomes. This article discusses the rationale for using combination antihypertensive therapy as initial therapy for high blood pressure in selected patients and reviews data from a study of 364 high-risk patients with Stage 2 hypertension in which a fixed-dose combination product (amlodipine besylate/benazepril HCl) proved more successful as initial therapy than high-dose monotherapy (amlodipine besylate) in reducing blood pressure.

Feasibility and effect on blood pressure of 6-week trial of low sodium soy sauce and miso (fermented soybean paste)

A double-blind, randomized placebo-controlled study was conducted to evaluate the feasibility of the long-term use of low-sodium soy sauce and miso in the general Japanese population and its effect on blood pressure (BP). Forty men and 24 women were randomly allocated to a low-sodium group (n=32) or a control group (n=32). Low-sodium soy sauce and miso, which were approximately 25% and 20% lower in salt content than common soy sauce and miso, were used in the study. The change in BP after a 6-week intervention was evaluated. There were no significant differences in age, sex, body mass index, BP or hypertension between the 2 groups before intervention. After the 6-week intervention, no significant change in BP was observed in the entire cohort. However, in those aged 40 years and older, 6.4 mmHg net reduction in diastolic BP with no significant change in systolic BP was noted in the low-sodium group. Taste evaluation for the low-sodium seasoning was considerably good. Replacing soy sauce and miso of the common type with the low-sodium alternative is feasible in the general population and could be the basis for a salt reduction strategy in the Japanese diet.

Achieving goal blood pressure in patients with type 2 diabetes: conventional versus fixed-dose combination approaches

Data from the Third National Health and Nutrition Examination Survey (NHANES III) demonstrate that only 11% of people with diabetes who are treated for high blood pressure achieve the blood pressure goal of <130/85 mm Hg recommended in the sixth report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI). The current study tests the hypothesis that initial therapy with a fixed-dose combination will achieve the recommended blood pressure goal in patients with type 2 diabetes faster than conventional monotherapy. This randomized, double-blind, placebo-controlled study had as a primary end point achievement of blood pressure <130/85 mm Hg. Participants (N=214) with hypertension and type 2 diabetes received either amlodipine/benazepril 5/10 mg (combination) or enalapril 10 mg (conventional) once daily for 4 weeks, titrated to 5/20 mg/day or 20 mg/day, respectively at this time, if target blood pressure was not achieved. Hydrochlorothiazide (HCTZ) 12.5 mg/day was added for the final 4 weeks, if target blood pressure was still not reached. Time from baseline to achieve blood pressure <130/85 mm Hg was shorter in the combination group (5.3+/-3.1 weeks combination vs. 6.4+/-3.8 weeks conventional; p=0.001). At 3 months, more participants in the combination group achieved treatment goal (63% combination vs. 37% conventional; p=0.002). Data analysis at 3 months comparing blood pressure control rates between the fixed-dose combination group (without HCTZ) to the conventional group (receiving HCTZ) showed an even greater disparity in blood pressure goal achievement (87% combination without HCTZ vs. 37% conventional group with HCTZ; p=0.0001). We conclude that initial therapy with a fixed-dose combination may be more efficacious than conventional monotherapy approaches for achieving blood pressure goals in the diabetic patient. A fixed-dose combination approach appears as safe as the current conventional approaches.

Gender, ethnicity and genetics in cardiovascular disease: part 1: Basic principles

Prior to 1993, most drug efficacy and safety trials were conducted in white males, although gender and racial differences in pharmacodynamics and pharmacokinetics have been documented since the early 1900s. Over the last 2 decades, supported by the FDA and legislation, attempts to include more women and minorities in clinical drug trials have been made, with limited success. Yet, there are important differences in pathophysiology and pharmacogenetics, as well as pharmacotherapeutic effectiveness. This is the first of 2 articles that review the basic scientific principles of such differences. In particular, genetic polymorphisms of cardiovascular candidate genes and drug metabolism are described. The pharmacodynamic and pharmacokinetic variations among genders and ethnicities are summarized.

Dahl salt-sensitive rats excrete 25-hydroxyvitamin D into urine

The plasma 25-hydroxyvitamin D concentration of Dahl salt-sensitive rats (S) is markedly decreased in response to high sodium chloride (salt) intake. We tested the hypothesis that urinary excretion is a mechanism for the decrease. Female S rats excreted 0.26 +/- 0.04 nmol 25-hydroxyvitamin D/24 h at wk 2 of high salt (80 g/kg) intake, five times that of female salt-resistant (R) rats at wk 2 of high salt intake and nine times that of S rats at wk 2 of low salt (3 g/kg) intake. The 25-hydroxyvitamin D binding activity in 24-h urine of S rats was 79 +/- 11 pmol/h at wk 2 of high salt intake, two times that in urine of S rats at wk 2 of low salt intake and > 35 times that in urine of R rats at wk 2 of low or high salt intake. We conclude that markedly decreased plasma 25-hydroxyvitamin D concentrations of S rats during high salt intake result in part from excretion of protein-bound 25-hydroxyvitamin D. Low plasma 25-hydroxyvitamin D concentrations in humans may also result in part from salt sensitivity, which is prevalent in > 50% of the United States hypertensive population.

Essential hypertension of Caribbean Hispanics: sodium, renin, and response to therapy

Little is known about essential hypertension in Hispanic Americans, despite the fact that they are the fastest-growing minority in the United States and have a disproportionate degree of hypertensive target organ damage. The authors studied 89 Caribbean Hispanic hypertensive patients who participated in six double-blind, randomized trials of antihypertensive agents. Demographics, laboratory data, sodium excretion, plasma renin activity, and atrial natriuretic peptide were obtained after 3-4 weeks on placebo. Blood pressure responses to angiotensin-converting enzyme (ACE) inhibitors, beta blockers, calcium channel blockers, hydrochlorothiazide (HCTZ), and fixed combinations of ACE inhibitors and HCTZ, were compared to the placebo values after 8-12 weeks of treatment. Patients had a multiple risk factor profile (obesity and diabetes) and a wide spectrum of blood pressure elevation, left ventricular hypertrophy, and hypertensive renal damage. Urine sodium excretion rates indicated inability to comply with salt restriction in 65% of patients. Plasma renin activity was lower than that of Hispanic normotensive controls, and 62% of patients had low-renin essential hypertension by renin profiling to sodium excretion. On analysis of variance, blood pressure reductions by calcium channel blockers, HCTZ, and ACE inhibitor/HCTZ combinations were significantly greater than that with placebo, while those of ACE inhibitors and beta blockers as monotherapy were not. The authors conclude that essential hypertension of Caribbean Hispanics is associated with multiple risk factors and is largely of the low-renin type. Responses to therapy are consistent with those observed in other populations with the low-renin phenotype and suggest salt-sensitivity of blood pressure in this population. Confirmation of the latter has implications for prevention and treatment of essential hypertension in Hispanics.

Reduction of cerebral injury in stroke-prone spontaneously hypertensive rats by amlodipine

Dihydropyridine Ca(2+) channel antagonists, initiated together with high salt intake, prevent the development of hypertension and subsequent cerebral damage in stroke-prone spontaneously hypertensive rats (SHRSP). We hypothesized that the dihydropyridine Ca(2+) channel antagonist amlodipine (approximately 15 mg/kg/day) could also reverse established hypertension and cerebral damage. SHRSP drank 1% NaCl from 8 weeks of age. Cerebral damage (cerebral edema and blood-brain barrier integrity) was investigated with magnetic resonance imaging twice a week. Systolic blood pressure was measured weekly. All rats developed severe hypertension and subsequent cerebral damage (defined as day 0). Untreated controls (n=7) died at day 12 (range: 7-28). Oral treatment with amlodipine (n=7), initiated at day 0, reduced systolic blood pressure, reversed cerebral edema and restored blood-brain barrier integrity. Systolic blood pressure remained low and eventually rats died after 450 days (range: 350-580) showing nephrosis but no recurrence of cerebral damage. In conclusion, established hypertension and cerebral damage are reversed by amlodipine in SHRSP.

Pathophysiology of chronic progressive renal disease in the African American patient with hypertension

Chronic renal failure and ESRD are major causes of morbidity, mortality, and chronic disability in patients in the United States. Hypertension is a major underlying cause of chronic progressive renal disease and continues to be a leading reason for the heavy burden of ESRD observed in African Americans. Hypertension is actually a syndrome of vascular pathology manifesting itself in patients by a constellation of common findings and attributes. These pathophysiologic alterations include dysregulation of arterial compliance, endothelial dysfunction, obesity and insulin resistance, abnormal sympathetic nervous system activation, accelerated atherosclerosis, left ventricular hypertrophy, and a propensity for increased vascular thrombogenesis among others. This review will focus on some of the important mechanisms possibly involved in the progression of renal disease in the setting of chronic hypertension.

Cultural competence: cardiovascular medications

Interethnic or racial differences are associated with enzyme polymorphisms, which are tiny variations in individuals in the physiology, absence, or presence of drug-metabolizing enzymes. The largest class of cardiovascular drugs investigated in pharmacogenetic studies is the antihypertensives. A number of studies have examined the best choices of antihypertensives for individuals within selected racial and ethnically defined populations. There is a fairly strong consensus about the pattern of antihypertensive treatment for black patients, but clear treatment directives for antihypertensive patients with other cultural affiliations have not emerged. Less information is reported about racial, ethnic, or cultural differences in effectiveness for other cardiovascular drugs. Nurses should consider whether the ethnic or racial affiliation of the patient places him or her more at risk for impaired drug metabolism. This article contains a guide for nursing assessment of culturally important factors related to polymorphisms.

Beyond the usual strategies for blood pressure reduction: therapeutic considerations and combination therapies

Rapidly accumulating clinical data have repeatedly demonstrated not only the critical importance of even small increases in blood pressure as a pathophysiologic factor in the development of cardiovascular disease, particularly in individuals with diabetes mellitus, but also the therapeutic necessity of more aggressive blood pressure reduction and the achievement of progressively lower blood pressure targets in reducing cardiovascular event rates. JNC VI has defined optimal blood pressure as <or=120/80 mm Hg, and Stage 1 hypertension as >or=140/80 mm Hg. Target blood pressures are now <or=130/80 mm Hg in patients with diabetes and <125/75 mm Hg for patients with hypertensive renal disease with proteinuria of >1 gm/24 hours. Achieving such target pressures is increasingly difficult, particularly in diabetic patients with chronic renal disease, who require complex multidrug antihypertensive regimens. This review attempts to provide some suggestions for constructing such antihypertensive regimens, and provides considerations for the appropriate use of diuretics and the most effective drug combinations. Factors potentially contributing to drug resistant hypertension include such problems as failure to maximize drug dosing, suboptimal diuretic use, noncompliance, and possible confounding effects of such concomitant medications as nonsteroidal and anti-inflammatory drugs or decongestants. The issues underlying drug-resistant hypertension are listed, together with strategies for overcoming this problem.

Appropriate use of calcium antagonists in hypertension

The paradigm for treating hypertension has shifted: Tighter control is the goal and a multidrug regimen is often the means, especially in high-risk patients. Although renin-angiotensin blockers are now the key components of such regimens, calcium antagonists can play an important role as well, given their demonstrated efficacy in controlling blood pressure.

Effects of isradipine or enalapril on blood pressure in salt-sensitive hypertensives during low and high dietary salt intake. MIST II Trial Investigators

This large multicenter study, tested the antihypertensive effects of isradipine, a dihydropyridine calcium channel blocker and enalapril, an angiotensin-converting enzyme inhibitor, in salt-sensitive hypertensive patients under low and high salt intake diets. After a 3-week (weeks -9 to -6) of ad lib salt diet, those patients who had a sitting diastolic blood pressure (SDBP) of > or =95 but < or =115 mm Hg qualified to enter a 3-week (weeks -6 to -3) placebo run-in low salt diet (50 to 80 mmol Na+/day). Then high salt (200 to 250 mmol Na+/day) was added to the placebo treatment for 3 weeks (weeks -3 to 0). Those patients who demonstrated an increase in SDBP > or =5 mm Hg from the low to high salt diet were considered salt sensitive and were randomized into a 4-week (weeks 0 to 4) double-blind treatment period of either isradipine 2.5 to 10 mg twice a day, enalapril 2.5 to 20 mg twice a day, or placebo. Then they entered a 3-week (weeks 4 to 7) placebo washout phase of low salt diet (50 to 80 mmol Na+/day). After week 7 and while the low salt diet was continued the patients were restarted on their double-blind treatment for 4 more weeks (weeks 7 to 11) and the study was completed. Of 1,916 patients screened, 464 were randomized into the double-blind treatment phase and 397 completed the study. Both isradipine and enalapril decreased the sitting systolic blood pressure (SSBP) and SDBP during the high salt diet, to a similar degree, whereas enalapril caused a greater reduction in SSBP and SDBP than isradipine during the low salt diet (11.3 +/- 1.2/7.7 +/- 0.7 mm Hg v 7.7 +/- 0.9/4.8 +/- 0.6 mm Hg, mean +/- SEM, respectively, P < .02). Within drugs, the effect of isradipine on blood pressure (BP) was higher during the high than the low salt diet (14.9 +/- 1.5 v 7.6 +/- 1.3 mm Hg for SSBP and 10.1 +/- 0.6 v 4.8 +/- 0.9 mm Hg for SDBP, P < .001), but enalapril exerted a similar effect during both diets. Because salt restriction lowered both SSBP and SDBP, the lowest BP achieved with both drugs were during the salt restriction phase.

Rationale for angiotensin II receptor blockers in patients with low-renin hypertension

African Americans outrank other ethnic groups in the United States in prevalence, early onset, and severity of hypertension. Furthermore, African Americans suffer the highest rates of mortality from cardiovascular, cerebrovascular, and end-stage renal disease. The recently concluded Heart Outcomes Prevention Evaluation (HOPE) study reports that the angiotensin-converting enzyme (ACE) inhibitor ramipril significantly reduced morbidity and mortality in a broad range of patients at high risk for cardiovascular events. These results strengthen the case for increasing the use of ACE inhibitor therapy. In accord with the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI) guidelines, antihypertensive monotherapy for African Americans is based on the known ability of diuretics and calcium channel blockers to produce greater reductions in blood pressure in this population than those attainable with beta blockers and ACE inhibitors. The national guidelines also suggest ACE inhibitors for all hypertensive patients with left ventricular dysfunction or nephropathy, which implies that African Americans must cross a clinical threshold to become candidates for these agents. The rationale for delaying ACE inhibitor therapy is due in part to a perceived unique pathobiology in hypertensive African Americans: an excess prevalence of salt sensitivity, hypervolemia, and low plasma renin activity (PRA). At first glance, it would seem intuitive to avoid agents that further depress the renin-angiotensin system (RAS) and choose agents that reduce plasma volume. However, most hypertensive African Americans are not hypovolemic. Furthermore, dietary sodium restriction and diuretic therapy raise PRA and improve the response to ACE inhibitors. The overall aim of this article is to explain the rationale for expanded use of drugs that block the RAS in African Americans and low-renin populations.

Theoretical basis and clinical evidence for differential effects of angiotensin-converting enzyme inhibitors and angiotensin II receptor subtype 1 blockers

Drugs that block the renin-angiotensin system have multiple mechanisms of action that may be beneficial in stabilizing or delaying progression of renal disease. The most important of these actions is the simultaneous control of both systemic and glomerular capillary hypertension. Angiotensin-converting enzyme (ACE) inhibitors are a class of drugs that have proven antihypertensive and antiproteinuric effects, with a demonstrated ability to delay progression of renal disease in conjunction with the ability to reduce systemic blood pressure. The mechanism of action for these drugs remains poorly described, but depends in part on an ability to reduce plasma angiotensin II levels and increase plasma bradykinin levels. Angiotensin II receptor subtype 1 (AT1) blockers differ in their mechanism of action from the ACE inhibitors. These drugs primarily block the binding of angiotensin II to its type 1 site. In so blocking the type 1 binding site, however, greater levels of circulating angiotensin II result, and the resultant biologic activity of angiotensin II or its metabolites such as angiotensin(1-7) and angiotensin(3-8) may be more directed to other angiotensin-binding sites. AT1 blockers have similar antihypertensive and antiproteinuric effects to those of ACE inhibitors and they may prove to be as useful as ACE inhibitors in delaying progression of renal disease. Because ACE inhibitors and AT1 blockers inhibit the renin-angiotensin system by different mechanisms, there is a possibility that combining them in clinical practice may prove efficacious for lowering blood pressure and for providing target organ protection.

The dietary guideline for sodium: should we shake it up? No

The current US dietary guideline for sodium is a limit of 2.4 g/d or 6 g NaCl/d. This amount of sodium is far in excess of any physiologic need and is likely an essential though not by itself sufficient primary cause of hypertension as well as a contributor to many other cardiovascular and renal abnormalities. The evidence incriminating the current excessive consumption of sodium derives from epidemiologic, experimental, and interventional data, most of which support a threshold of approximately 100 mmol/d for the harmful effects of sodium to be expressed. Although the current recommendation may not be low enough to go below that threshold, it is an appropriate and attainable goal for now.

Hypertensive cardiovascular disease in African Americans

Hypertension is the most common public health challenge in the United States because of its prevalence and associated increase in comorbid cardiovascular diseases. Yearly expenses related directly or indirectly to the treatment and detection of hypertension in the United States are approximately $10 billion, excluding the enormous yearly financial burden of $259 billion and the social burden from heart disease and stroke, which remain the first and third leading causes of death, respectively, in the United States. Despite the importance of these observations, blood pressure is poorly controlled in the United States.