Implications of a health lifestyle and medication analysis for improving hypertension control

BACKGROUND

National Health and Nutritional Examination surveys have documented poor rates of hypertension treatment and control, leading to preventable morbidity and mortality.

OBJECTIVES

To examine covariation in the medication and health lifestyle beliefs and behaviors of persons with hypertension to identify and profile distinct subgroups of patients.

METHODS

A sample of 727 patients with hypertension, weighted to match the 1992 National Health Interview Survey age and sex distribution of patients with hypertension, was interviewed by telephone about their beliefs and behaviors regarding hypertension and its management. Cluster analysis of key variables was used to identify 4 patient types.

RESULTS

Subgroups differed significantly. Group A members use an effective mix of medication and health lifestyle regimens to control blood pressure. Group B members are most likely to depend on medication and have high adherence rates. Yet they also have high rates of smoking (29%) and alcohol use (average, 104 times per year) and are less likely to exercise regularly. Group C members are most likely to forget to take medication, are likely to be obese, and find it most difficult to comply with lifestyle changes (except for very low rates of smoking and alcohol use). Group D members are least likely to take medication, most likely to change or stop medication without consulting their physician (20%), most likely to smoke (40%), and least likely to control diet (29%). Group A and B members have better health outcomes than group C and D members.

CONCLUSIONS

Optimal management strategies are likely to differ for the 4 patient types. Further research should be conducted to validate these findings on a separate sample and to devise and test tailored management algorithms for hypertension compliance and control.

Glucocorticoid receptor distribution in rat testis during postnatal development and effects of dexamethasone on immature peritubular cells in vitro

In this study, the occurrence of the glucocorticoid receptor in the rat testis during early stages of postnatal development and its potential functional significance were investigated. Quantitative analyses of immunohistochemically labelled paraffin sections revealed that the receptor was present during all stages of postnatal development in the nuclei of interstitial cells such as Leydig cells, macrophages and fibroblasts, and endothelial cells of blood vessels. The labelling index increased initially, with maximum levels reached within the second week of postnatal development, and decreased thereafter. Within the seminiferous tubules, the glucocorticoid receptor could be detected in the nuclei of germ cells as well as Sertoli cells, reaching the highest levels in 3-week-old rats, mainly due to immature germ cell staining. In contrast, approximately 50% of the peritubular cell nuclei were stained throughout postnatal development. In vitro experiments on immature and immortalized peritubular cells demonstrated a dose-dependent and significant decrease in proliferation and fibronectin secretion after administration of dexamethasone. The data of this study suggest that glucocorticoids have a consistently repressive effect on peritubular cells throughout postnatal development. In summary, labelling of germ cells, especially in immature rats, might indicate an inhibition of spermatogenesis by corticosteroids.

Interrupting the renin-angiotensin system: the role of angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists in the treatment of hypertension

The renin-angiotensin system has two roles in clinical hypertension: its vasoconstrictor properties directly govern blood pressure, and its actions on arterial smooth muscle, connective tissue, and endothelial integrity affect cardiovascular prognosis. Additionally, the direct actions of angiotensin II on the function and structure of the heart and renal vasculature influence clinical events. Angiotensin-converting enzyme (ACE) inhibitors have produced functional and clinical outcome benefits in clinical trials of patients with congestive heart failure, systolic dysfunction after myocardial infarction, and diabetic nephropathy. Similar favorable trends have been noted in observational studies in hypertension. Because such enzymes as chymase can substitute for ACE, the ACE inhibitors may not completely block angiotensin II formation, although they enhance bradykinin accumulation and secondarily stimulate nitric oxide and vasodilatory prostaglandins. Angiotensin II receptor blockers (ARB) selectively block the angiotensin II type 1 (AT1) receptor that not only mediates the known effects of angiotensin II but, according to recent reports, might be responsible for sequestering angiotensin II molecules in renal and cardiac cells. Moreover, by increasing plasma concentrations of angiotensin II, the ARB stimulate the unblocked angiotensin II type 2 (AT2) receptors, which-if they exist in meaningful numbers in human hypertension-mediate additional vasodilatory and antiproliferative effects. The contrasting actions of these two classes of drugs might be clinically relevant. For example, they may have additive antihypertensive efficacy; they have differing effects on renal plasma flow; and in a small pilot study of patients with congestive heart failure, the ARB demonstrated an apparent advantage in survival. Ongoing clinical trials will try to determine whether the effects of ARB can equal or even exceed the beneficial effects of ACE inhibitors on cardiovascular prognosis.

Is high blood pressure a late manifestation of the hypertension syndrome?

Because hypertension has generally been defined as a disease of elevated systolic and diastolic blood pressure, the goals of treating hypertension have been simply to normalize the blood pressure. It was believed that if normal blood pressure were achieved, patients with hypertension would experience significant reductions in the incidence of associated cardiovascular events. However, studies to assess cardiovascular events in patients with hypertension have repeatedly demonstrated that reducing blood pressure results in very impressive reductions in cerebrovascular disease but in reductions of only about 16% in coronary artery disease, which is far lower than what was statistically predicted from the reductions in blood pressure. Although there are probably several reasons for the poor rate of reductions in the incidence of coronary artery disease, one of the most compelling appears to be the realization that hypertension is not simply a disease of numbers but rather a complex inherited syndrome of cardiovascular risk factors, all of which contribute to the development of heart disease in these patients. Included in the hypertension syndrome are abnormalities of lipid profile and insulin resistance, changes in renal function, endocrine changes, obesity, abnormalities of coagulation factors, and changes in the structure and function of the left ventricle and of vascular smooth muscle in the vasculature. In many patients, high blood pressure is a late manifestation of this disease process and is preceded by some or all of the associated cardiovascular risk factors. This paradigm suggests that therapeutic strategies for hypertension should be interventions that target both the hemodynamic and nonhemodynamic mechanisms of this syndrome to more completely reduce cardiovascular morbidity and mortality in patients with hypertension.

Comparisons of the effects of different long-acting delivery systems on the pharmacokinetics and pharmacodynamics of diltiazem

The benzothiazepine calcium channel antagonist diltiazem is a short-acting drug. To achieve effective 24-h blood pressure control with once-daily dosing, it relies on various extended drug-delivery systems that have grown in importance as a result of the recent reports relating the use of short-acting calcium channel antagonists to increased cardiovascular morbidity. This study examines the pharmacokinetics and resulting pharmacodynamics of two different delivery systems, each loaded with 240 mg of diltiazem and administered to 40 moderately hypertensive patients in a randomized, double-blind crossover trial. After a 4-week, single-blind placebo lead-in, patients with a clinical diastolic blood pressure of > or =100 mm Hg were randomized to either the single or dual microbead diltiazem delivery system for a 4-week period. At the end of this period, each subject was evaluated with 24-h ambulatory blood pressure monitoring and subjected to 24-h inpatient pharmacokinetic analysis on separate days. This was followed by a similar 4-week period in which each subject was treated with the alternative delivery system. For diltiazem, the area under the curve for plasma concentration versus time and the maximum plasma concentration attained by the single microbead system exceeded the values achieved by the dual bead system by 15% and 25%, respectively. These differences were greatest from the 3rd through the 13th h after dosing. During this period, both systolic and diastolic ambulatory blood pressure was significantly lower when the single microbead system was used. When compared with baseline blood pressure, blood pressure reductions achieved with the single microbead system exceeded reductions achieved with the dual microbead system by at least 2 mm Hg for 10 of the 24 postdose hours. Heart rates were slightly reduced but not significantly different. This improved blood pressure control at higher plasma levels of diltiazem suggests that a more efficient delivery system could provide better blood pressure control for identical doses of diltiazem.

[30-day mortality after heart surgery: a pilot project of the Working Party of Directors of Hospital Cardiology Departments]

BACKGROUND AND OBJECTIVE

30-day mortality after operation is generally accepted as a central standard of quality, especially in regard to cardiac operations. The Working Party of Directors of Hospital Cardiology Departments (Arbeitsgemeinschaft Leitender Kardiologischer Krankenhausärzte, ALKK) in Germany set up a pilot project to analyse whether by direct communication with patients by a database centre the expenditure incurred in collecting complete data can be decisively reduced and full documentation of outcome can in this way be obtained even for a large multi-centre patient cohort.

PATIENTS AND METHODS

Between 1.6.1997 and 31.3.1998, data were consecutively collected by questionnaire on all patients registered for a cardiac operation at 85 of the 135 ALKK centres. The questionnaire included data about each patient and the indication for operation as well as the estimate of operative risk, assigned to one of five risk categories by the referring cardiologist either alone or in conjunction with the cardiac surgeon.

RESULTS

Until 30.9.1998, the data were obtained on 11,349 patients who had given informed consent (response rate 99.99%), including survival figures. 824 (7.3%) patients had not undergone the planned cardiac surgery, 134 having died before the data of operation. The 30-day postoperative mortality, obtained in 99.99% of the 10,525 patients, was 3.92%. The operative mortality was lowest, at 3.73%, for aortocoronary bypass only (n = 7932), highest for aortocoronary bypass plus valvular operation (n = 785), at 8.04%. There was good agreement between the cardiologists' preoperative risk assessment and the observed mortality.

CONCLUSIONS

The 30-day mortality after cardiac operation can be obtained almost completely and with reasonable expenditure even for a large patient cohort. The results confirm that hospital mortality data definitely understate the overall operative risk. The methodology used in this pilot project, namely the inclusion of information from the patients by questionnaire, can also be applied to clinical results in other areas.

Dynamics of single dye molecules observed by confocal imaging and spectroscopy

The fluorescence emission of single rhodamine dye molecules (rhodamine 6G and rhodamine 630) at room temperature was analyzed by using scanning confocal laser microscopy in conjunction with polarization analysis, fluorescence spectroscopy, time-resolved detection (minutes to microseconds), and excitation saturation. Results are presented and discussed 1) for samples with dye molecules at the glass-air interface and 2) covered with an additional thin protective polymer film (polyvinylbutyral). Under the polymer layer, the single-molecule fluorescence was more stable than the glass-air interface. This result may be explained by fewer spontaneous variations of the fluorescence rate, polarization changes, spectral shifts, and longer photochemical lifetimes.

The ethics of using placebo in hypertension clinical trials

USE OF PLACEBO CONTROLS: Placebo controls can enhance the value of two types of hypertension trials: measurement of the blood pressure-lowering efficacy of antihypertensive treatment and determination of whether therapeutic interventions can affect clinical endpoints. However, the possibility of adverse outcomes in hypertensive patients allocated to placebo therapy raises ethical concerns. EFFICACY STUDIES: Placebo controls in efficacy studies are particularly helpful in thoroughly quantifying the effect of treatment. The hazard to patients can be minimized by exposing them to placebo for the least possible amount of time and, assuming that blood pressure is itself the primary variable, reducing the probability of cardiovascular events by excluding subjects with severe hypertension or major concomitant risk factors. ENDPOINT STUDIES: Endpoint studies present a more difficult challenge, for they are designed in anticipation of cardiovascular events and patients at high risk are often enrolled in order to more rapidly achieve the required number of endpoints for statistical analysis. In such circumstances, positive therapeutic controls, despite the complexities of analysis, must be preferred to placebo. EARLY-STAGE HYPERTENSION: Important questions regarding the management of early-stage hypertension remain, and despite official treatment guidelines recommendations, currently based chiefly on extrapolation and judgement, many physicians routinely withhold therapy in mild hypertension, even when other risk factors are present. With appropriate safeguards, placebo-controlled trials may be necessary to examine potential benefits of therapy in such patients. Indeed, resolving therapeutic uncertainty and creating well founded recommendations for the future management of the many patients with milder forms of hypertension can make placebo controls both ethical and appropriate.

Unsolved problems in treating hypertension: rationale for new approaches

Two major problems continue to challenge hypertension experts and clinical practitioners. The first is the apparently simple issue of controlling blood pressure; only one-quarter of hypertensive patients in the United States have blood pressures reduced to less than 140/90 mm Hg. Even those known to be receiving treatment have barely a 50% success rate. Explanations include inadequate commitments by physicians to achieve target blood pressures, but it is also likely that effectively decreasing blood pressure--despite the currently available panoply of antihypertensive agents--is a truly difficult task. The second problem is that despite our success in decreasing stroke incidence, hypertension treatment with traditional agents, largely diuretic-based, has not adequately protected patients against coronary events and renal insufficiency. Such new drug classes as angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers, and calcium channel blockers exhibit vascular effects that might inhibit atherosclerotic changes and reduce clinical events, but we are still awaiting definitive confirmation of these properties from ongoing clinical outcomes studies in hypertension. Therapy with fixed combinations of antihypertensive drugs is now recognized as a potentially useful approach. Innovative combinations, including ACE inhibitors and calcium channel blockers, can provide enhanced antihypertensive efficacy while avoiding or minimizing adverse metabolic and clinical side effects. These approaches are also convenient and cost-effective. It remains to be learned whether newer drug combinations might exhibit additive cardiovascular protective actions.

Comparison between moexipril and atenolol in obese postmenopausal women with hypertension

The present study investigated the effect of the new ACE-inhibitor moexipril versus the beta 1-adrenergic blocker atenolol on metabolic parameters, adverse events (AEs) and sitting systolic (SSBP) and sitting diastolic blood pressure (SDBP) in obese postmenopausal women with hypertension (stage I and II). After a 4-week placebo run-in phase, 116 obese, postmenopausal women with primary hypertension were randomised into two treatment groups receiving once daily dosages of either moexipril 7.5 mg or atenolol 25 mg initially (mean age: 57 +/- 7 years in both groups; mean weight: 94 kg in the moexipril group and 89 kg in the atenolol group, corresponding to a body mass index (BMI) of 35.2 kg/m2 and 34.1 kg/m2 in both groups, respectively). After 4 and 8 weeks, the dosages were uptitrated to moexipril 15 mg, or if necessary to moexipril 15 mg/hydrochlorothiazide (HCTZ) 25 mg, or to atenolol 50 mg and atenolol 50 mg/HCTZ 25 mg, in patients whose blood pressure was not sufficiently controlled. At endpoint, metabolic parameters (total cholesterol, triglycerides, LDL, HDL, glucose, insulin) were not significantly altered in either treatment group. Most frequent adverse events under monotherapy (moexipril/atenolol) were asthenia (5.3/13.0%), headache (13.2/21.7%), cough (7.9/6.5%), pharyngitis (21.1/8.7%) and peripheral oedema (5.3/13.0%). Overall at least one AE was reported in 66% of the patients treated with moexipril and in 78% of those treated with atenolol. Reduction of SSBP/SDBP at endpoint was 14.7 +/- 1.9/10.0 +/- 1.1 and 8.7 +/- 1.9/8.4 +/- 1.1 mmHg after treatment with moexipril and atenolol, respectively. The results showed that moexipril and atenolol are equally effective in reducing blood pressure without adversely affecting blood lipids and carbohydrate metabolism.

Rationale and design for the Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) Trial

The Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) Trial is a randomized, prospective, double-blind, parallel-group, two-arm, actively controlled, multicenter, international 5-year clinical trial involving 15,000 patients. CONVINCE will compare the incidence of fatal or nonfatal myocardial infarction (MI), fatal or nonfatal stroke, or cardiovascular-disease-related death in two antihypertensive treatment regimens. One treatment arm begins with controlled onset-extended release (COER)-verapamil, which has its major antihypertensive effect 6-12 hours after administration. The other arm (standard of care (SOC)) begins with either hydrochlorothiazide (HCTZ) or atenolol, one of which is preselected by the investigator for an individual patient prior to randomization. Secondary objectives include comparisons of the regimens for each of the components of the primary endpoint (separately), death or hospitalization related to cardiovascular disease, efficacy in lowering blood pressure to goal, primary events occurring between 6 am and noon, all-cause mortality, withdrawals from blinded therapy, cancer, and hospitalizations due to bleeding. Patients may be enrolled if they are hypertensive and at least 55 years of age and have an established second risk factor for cardiovascular disease. Initial medications include COER-verapamil (180 mg/d), HCTZ (12.5 mg/d), or atenolol (50 mg/d). Initial doses are doubled if blood pressure (BP) does not reach goal (systolic BP < 140 mm and diastolic BP < 90 mm Hg). If BP is not controlled by the higher dose of the initial medication, HCTZ is added to COER-verapamil, or the SOC choice not initially selected is added in the SOC arm. An ACE-inhibitor is recommended (although nearly any open-label medication is allowed) as the third step for patients whose BP is not adequately controlled or who have a contraindication to one of the two SOC medications. Patients take two sets of tablets daily, one in the morning and one in the evening. Although most patients switch from an established antihypertensive medication to randomized treatment, untreated patients with stages I-III hypertension (SBP between 140 and 190 or DBP between 90 and 110 mm Hg) are eligible. Outcomes are monitored by an independent Data and Safety Monitoring Board. Enrollment began during the third quarter of 1996, and follow-up is to be completed in the third quarter of 2002.

Translating data on antihypertensive drugs into clinical practice

Two problems in the treatment of hypertension continue to be largely unsolved. The first, and more simple, is our inability to adequately control blood pressure in the majority of hypertensive patients. This not only reflects the difficulty of retaining patients in effective treatment programs, but also of convincing physicians to strive for optimal blood pressure levels. There is a continuing need for new antihypertensive drugs and combinations to help accomplish these goals. The second major problem is that the major clinical endpoints, including coronary events and renal failure, have not been adequately reduced by traditional therapies. Standard regimens, particularly those including diuretics, have protected against strokes and heart failure. Our improved understanding of vascular biology in hypertension has directed interest to the mechanisms in hypertensive patients that might accelerate atherosclerosis and vascular events in these individuals. This involves addressing the concomitant metabolic risk factors that comprise the "Hypertension Syndrome," and, perhaps of equal importance, finding therapies that directly inhibit unwanted types of growth and proliferative activities within the walls of critical arteries. Many substances within the endothelium and the vascular wall may participate as initiators or mediators of pathology, but most information thus far has focused on the renin-angiotensin system. Angiotensin converting enzyme inhibitors (and potentially angiotensin receptor blockers) have provided coronary and renal protection in various cardiovascular conditions, though not yet in formal hypertension trials. Calcium channel blockers have also shown promise, including recent stroke and cardiovascular benefits in patients with isolated systolic hypertension, but, again, definitive coronary data in hypertension are awaited. Unless concomitant conditions mandate the selection of a particular antihypertensive drug class, physicians currently have a dilemma: should they choose drugs from older classes that have not provided full protection? Or, should they prescribe newer agents with exciting potential but with, as yet, unproved endpoint benefits in hypertension? Until currently ongoing prospective trials of antihypertensive therapy are completed, physicians must be guided by their own interpretations of the available data.

Comparative accuracy of three automated techniques in the noninvasive estimation of central blood pressure in men

Automated devices have regularly replaced manual sphygmomanometry for the determination of blood pressure not only in homes and clinics, but also in emergency and critical care settings. Few studies exist that correctly assess the accuracy of these devices, and even fewer that specifically compare commercially available units that rely on different physiologic events for measurement. Six hundred pressure measurements were obtained from 120 subjects using 1 of 3 randomly selected blood pressure monitors. In addition, central arterial pressure measurements were obtained simultaneously and directly from the ascending aorta of each subject. Overall, these devices tended to overestimate diastolic (+2.5 mm Hg, p < 0.0001) and mean (+3.8 mm Hg, p < 0.0001) pressures, but not systolic (+0.7 mm Hg, p = NS) pressure. Compared with the other 2 devices, device I, relying on oscillometric detection, demonstrated a significantly smaller mean absolute error for diastolic pressure (4.9 +/- 3.0 vs 7.0 +/- 4.8 and 6.2 +/- 5.3 mm Hg, p < 0.0001) and mean pressure (4.0 +/- 3.2 vs 7.8 +/- 5.9 and 8.6 +/- 7.5 mm Hg, p < 0.0001), and a trend toward smaller error with systolic pressure (6.8 +/- 6.5 vs 7.3 +/- 6.8 and 8.0 +/-5.6 mm Hg, p = 0.19). Clinically significant (+/-10 mm Hg) errors were common with each device (24.8% overall), but serious (+/-20 mm Hg) errors were unusual (3.2%) and did not occur at all with device I during diastolic and mean pressure measurement. All of the devices tested could be expected to perform satisfactorily in most clinical settings provided that an average error of 4.0 to 8.6 mm Hg is tolerable. This level of accuracy typically extended throughout the range of pressures anticipated in most noncritical clinical situations. As implemented in the devices tested, noninvasive measurement by oscillometry with stepped deflation is more accurate than automated auscultation.

Dose-related antihypertensive effects of irbesartan in patients with mild-to-moderate hypertension

Two multicenter, double-blind, placebo-controlled, parallel group studies were conducted to evaluate the efficacy, safety, pharmacokinetics, and pharmacodynamics of the angiotensin II receptor (AT1 subtype) antagonist irbesartan. The effect of irbesartan withdrawal and the effect of adding hydrochlorothiazide (HCTZ) to irbesartan were also assessed. After a placebo lead-in phase, all patients were randomized to 8 weeks of double-blind therapy with either placebo (n = 158) or irbesartan at doses of 1, 5, 10, 25, 50, 100, 200, or 300 mg (n = 731 total) orally once daily. Irbesartan reduced blood pressure in a dose-related manner. Reductions from baseline in trough seated diastolic blood pressure ranged from 7.5 mm Hg for 50 mg irbesartan to 11.6 mm Hg for 300 mg irbesartan. At week 8, statistically significant reductions over placebo were observed in trough seated blood pressure with all irbesartan doses > or = 50 mg. These reductions reached statistical significance versus placebo within 2 weeks with 100, 200, and 300 mg irbesartan. Plasma irbesartan concentrations correlated with dose. Angiotensin II and aldosterone levels generally showed dose-related changes, consistent with AT1 receptor blockade. In patients not controlled at 8 weeks, the addition of 12.5 mg HCTZ resulted in further dose-related reductions in blood pressure. Irbesartan demonstrated a placebo-like safety profile and no dose-related toxicity. Irbesartan, administered alone or in combination with HCTZ, was well tolerated. Withdrawal of irbesartan did not result in rebound hypertension or adverse events. Thus, once-daily irbesartan is both an effective and safe antihypertensive agent for the treatment of mild-to-moderate hypertension.

Comparison of effects of controlled onset extended release verapamil at bedtime and nifedipine gastrointestinal therapeutic system on arising on early morning blood pressure, heart rate, and the heart rate-blood pressure product

We assessed the differential effects of a chronotherapeutic agent (controlled-onset extended release [COER] verapamil), administered at bedtime versus a conventional, homeostatic therapy (nifedipine gastrointestinal therapeutic system [GITS]) taken in the morning, on early morning and 24-hour blood pressure (BP), heart rate (HR), and the HR x systolic BP product. The study was a multicenter (n = 51), randomized, double-blind prospective clinical trial with a 10-week treatment period. Dose titration was performed by study investigators based on systolic and diastolic BP values at the doctor's office. Ambulatory BP monitoring was performed at placebo baseline, after 4 weeks of stable double-blind therapy, and at end of the study. Twenty-four-hour BP profiles were studied in 557 hypertensive patients. Changes in BP, HR, slope of the rate of rise of BP and HR, and the HR-systolic BP product during the 4 hours from 1 hour before to 3 hours after awakening were evaluated. The study was powered to show equivalence between the 2 regimens, predefined as a difference between treatment groups in mean change from baseline in early morning BP of +/- 5 mm Hg systolic and +/- 3 mm Hg diastolic. Changes in the early morning BP fell within the definition of equivalence for the 2 treatment strategies (-12.0/-8.2 mm Hg for COER-verapamil and -13.9/-7.3 mm Hg for nifedipine GITS). Changes in both the early morning HR and rate-pressure product were significantly greater following COER-verapamil therapy versus nifedipine GITS (HR, -3.8 beats/minute vs +2.6 beats/minute, p < 0.001 and HR-systolic BP product, -1,437 beats/min x mm Hg vs -703 beats/min x mm Hg, respectively, p < 0.001). Changes in ambulatory BP demonstrated clinically similar reductions for the awake period, but nifedipine GITS lowered systolic BP to a greater extent than COER-verapamil during sleep (-11.0 vs -5.8 mm Hg, p < 0.001). COER-verapamil and nifedipine GITS had equivalent effects (+/- 5/3 mm Hg) on early morning BP. In addition, both extended-release calcium antagonists effectively lowered 24-hour BP. However, COER-verapamil had greater effects than nifedipine GITS on early morning hemodynamics (HR, HR-systolic BP product, rate of rise of BP and HR) and lesser effects during sleep due to its intrinsic pharmacologic properties and chronotherapeutic delivery system.

Comparison of type 1 angiotensin II receptor blockers and angiotensin converting enzyme inhibitors in the treatment of hypertension

RENIN-ANGIOTENSIN SYSTEM AND HYPERTENSION: The renin-angiotensin system is integral to the mechanisms that sustain hypertension. Hypertensive patients with inappropriately high renin levels have an increased risk of cardiovascular events, and thus there is continuing interest in treating hypertension with drugs that not only reduce blood pressure but also have an inhibitory effect on the renin-angiotensin system. INHIBITORS OF THE RENIN-ANGIOTENSIN SYSTEM: Angiotensin converting enzyme (ACE) inhibitors decrease blood pressure and ameliorate the symptoms of congestive heart failure. Drugs that selectively block the AT1 angiotensin II receptor are now entering clinical practice for the treatment of hypertension and, very likely, congestive heart failure. PHARMACOLOGIC DIFFERENCES: There are some important theoretical differences between ACE inhibitors and AT1 blockers in their actions on the renin-angiotensin system. ACE inhibitors ostensibly prevent the formation of angiotensin II. However, this action is far from complete, as measurable plasma concentrations of ACE remain during chronic therapy with these agents. AT1 receptor blockers work selectively at the AT1 receptor, leaving the AT2 receptor unaffected. The importance of this selectivity has not yet been established, but AT2 receptors are thought to mediate inhibitory effects on growth. It has been postulated that the selective blockade by this new class of drugs will directly decrease the growth-promoting actions of angiotensin II at the AT1 receptor, while leaving the growth-inhibitory effects of the AT2 receptor unaffected. The clinical relevance of these differing pharmacologic properties of ACE inhibitors and AT1 blockers have not yet been established. BLOOD PRESSURE, METABOLIC AND RENAL EFFECTS: AT1 receptor blockers appear to have relatively high trough:peak efficacy ratios compared with ACE inhibitors. However, in patients with essential hypertension compared with normal volunteers, the M value, a measure of glucose clearance and insulin sensitivity, is reduced. Both the ACE inhibitor delapril and the AT1 blocker candesartan have shown a beneficial effect on insulin sensitivity, and candesartan appears to restore the M value to normal. While ACE inhibitors have been shown to have strongly beneficial actions in the kidneys, comparable data are not yet available for AT1 blockers.

SIDE EFFECTS

The relatively common problem of cough observed with ACE inhibitors does not occur with AT1 blockers.

FUTURE WORK

Future studies must address metabolic and cardiovascular questions that have not yet been answered. It will also be of interest to determine whether the combination of AT1 blockers and ACE inhibitors, especially in more resistant forms of congestive heart failure or hypertension, might confer additive benefits.

The importance of pulsatile components of hypertension in predicting carotid stenosis in older adults

OBJECTIVE

To evaluate pulsatile components of the blood pressure as risk markers for carotid stenosis in isolated systolic hypertension.

DESIGN

Duplex scans with Doppler measures of the blood flow velocity were used to diagnose carotid stenosis in 187 participants in the Systolic Hypertension in the Elderly Program and in 187 normotensive and mildly hypertensive control subjects.

METHODS

The systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure, and mean arterial pressure (MAP) were selected as independent variables. A logistic regression model for carotid stenosis was used to adjust for potentially confounding risk factors. Serial models, each containing single or double blood pressure variables, were run to compare risk markers for carotid stenosis. Receiver operating characteristic curves were compared to assess the predictive value of each model.

RESULTS

In the multivariate analysis, both the SBP (P = 0.005) and the pulse pressure (P < 0.001) were predictive of carotid stenosis, but the DBP and MAP were not. However, when either the SBP or the pulse pressure was included in the model, the DBP was associated negatively with carotid stenosis (P < 0.001 and P = 0.023, respectively). An increased pulse pressure and a decreased DBP were independent risk markers for carotid stenosis. Comparison of receiver operating characteristic curves indicated that the pulse pressure had superior predictive value to the SBP (P = 0.034).

CONCLUSIONS

The pulse pressure is the single best predictor of carotid stenosis. There is a negative correlation between the DBP and carotid stenosis for subjects with isolated systolic hypertension, but this can be demonstrated only after one has stratified for the SBP or for the pulse pressure. Thus, the pulsatile components of the blood pressure, increased pulse pressure and decreased DBP, are the most sensitive risk markers for the diagnoses of carotid stenosis.