Effects of an angiotensin-converting-enzyme inhibitor, ramipril, on cardiovascular events in high-risk patients

Are angiotensin converting enzyme inhibitors and angiotensin receptor blockers becoming the treatment of choice in African-Americans?

African-American patients constitute a significant and important group who are at high risk for developing hypertension-related complications. The proportion of African-American patients succumbing to or suffering from cardiovascular, renal, and neurologic sequelae is unacceptably high. Therefore, it is extremely crucial to develop appropriate therapeutic strategies for this vital subset of our society. The renin-angiotensin system may play a role in the pathophysiology of hypertension-related diseases, and therefore drugs that block this system, ie, angiotensin converting enzyme inhibitors and angiotensin receptor blockers, may have a special indication for African-American patients. Although these drugs may not be the most efficacious agents in terms of blood pressure reduction, they have a major benefit in offering target organ protection and arresting disease progression in the African-Americans. Hence, contrary to the old notions, drugs blocking the renin-angiotension system have an important place in the management of hypertension and related disorders in African-American patients.

Central role of the AT(1)-receptor in atherosclerosis

The renin-angiotensin system plays a major role in the pathogenesis of atherosclerosis. Most known effects of angiotensin II are mediated via activation of the AT(1)-receptor, which is in turn influenced to a great degree by levels of expression of the AT(1)-receptor. AT(1)-receptor activation is not only involved in vasoconstriction, water and salt homoeostasis and control of other neurohumoral systems, but also induces reactive oxygen species production, cellular hypertrophy and hyperplasia and apoptosis. Expression of this G-protein-coupled receptor is regulated by multiple factors. Among other conditions, oestrogen deficiency and hypercholesterolaemia increase AT(1)-receptor expression. Experimental data suggest that this augments the actions of angiotensin II, contributes to endothelial dysfunction, increases vascular production of reactive oxygen species, and via these mechanisms promotes atherosclerosis. Because of this, AT(1)-receptor regulation is likely to be critical in the development and progression of vascular lesions. Interventional studies demonstrated that ACE inhibitors which reduce AT(1)-receptor activation, improve endothelial dysfunction and inhibit onset and progression of atherosclerosis. The more specific AT(1)-receptor antagonists have also been shown to decrease blood pressure, protect renal function and to improve endothelial function. Thus, there is compelling evidence that AT(1)-receptor activation participates in the pathogenesis of atherosclerosis, and more importantly, that treatment regimens aiming at inhibition of AT(1)-receptor activation are promising anti-atherosclerotic therapeutic options.

PAI-1 in human hypertension: relation to hypertensive groups

BACKGROUND

Although the renin-angiotensin system and insulin resistance (IR) have been identified as major regulators of plasminogen activator inhibitor type-1 (PAI-1), their roles in hypertensive subjects is not clearly defined.

METHODS

We examined the effect of dietary salt restriction on PAI-1 levels in 239 hypertensive subjects from three centers. Subjects were placed on a 200 and 10 mmol/day sodium diets for 1-week periods. Plasma renin activity (PRA) and PAI-1 levels were measured on the last day of both diets and fasting insulin, glucose, and aldosterone (ALDO) levels, only on the low salt diet.

RESULTS

Sodium restriction increased PAI-1 levels from 32.1 +/- 2.5 ng/mL to 39.8 +/- 3.2 ng/mL (P = .009). There was a strong positive correlation between PAI-1 levels and PRA (r = 0.228, P = .0004), IR (r = 0.222, P = .001), triglycerides (r = 0.275, P < .001), and ALDO (P = .018 for linear trend). The patients were divided into low renin (low IR and ALDO levels), nonmodulators (normal PRA, high IR, and low ALDO levels), and modulators (normal PRA, intermediate IR, and normal ALDO levels) groups to assess the relative contribution of each factor to PAI-1 levels. Modulators had significantly (P = .019) higher PAI-1 levels compared to the low renin and nonmodulators who had similar PAI-1 levels.

CONCLUSIONS

Plasma renin activity, IR, and ALDO all correlate with PAI-1 levels in the hypertensive subjects. However, the data suggest that ALDO may be an important factor contributing to the variability of PAI-1 levels in individual hypertensive subjects.

Use of secondary preventive drugs in patients with acute coronary syndromes treated medically or with coronary angioplasty: results from the nationwide French PREVENIR survey

BACKGROUND

There is evidence that several classes of drugs are beneficial for secondary prevention in patients with coronary artery disease.

OBJECTIVE

To compare the use of secondary preventive drugs in patients with acute coronary syndromes given conservative treatment or percutaneous coronary interventions.

DESIGN

The PREVENIR survey was designed to assess the management of patients with acute coronary syndromes admitted to hospital in France in January 1998. Drugs prescribed at hospital discharge were recorded retrospectively from the hospital records, and treatment at six months was assessed prospectively.

SETTING

University hospitals, general hospitals, and private clinics throughout the country.

RESULTS

Of 1394 patients participating in the survey, 668 underwent coronary angioplasty during the initial hospital stay and 706 had medical treatment only. At hospital discharge, aspirin, beta blockers, and statins were prescribed significantly more often in patients undergoing angioplasty. Using multivariate logistic regression, coronary angioplasty was an independent predictor of treatment with aspirin (odds ratio 3.55), statins (1.92), and beta blockers (1.41). Compared with treatment at discharge, only statin use differed at six months, with a significant increase both in patients treated medically and in those who had undergone angioplasty. Increased use of statins, aspirin, and beta blockers was significantly correlated with coronary angioplasty during the initial hospital stay.

CONCLUSIONS

In this national French survey, patients treated with percutaneous coronary interventions were more likely to receive secondary preventive drugs than patients receiving medical treatment alone.

The reno-protective role of AT(1)-receptor blockers

In the 1970s and 1980s it became evident that progression of renal disease and blood pressure are correlated. Subsequently, it was shown that antihypertensive treatment, especially with agents that block the renin-angiotensin system (RAS), could slow the progression of diabetic renal disease. Several studies, particularly with RAS blockers, have confirmed beneficial effects on urinary albumin excretion in patients with diabetes and microalbuminuria or proteinuria. There are good reasons to explore dual blockade of the RAS with an AT(1)-receptor blocker and an ACE inhibitor. Receptor blockers may block the effects of angiotensin II more effectively than ACE inhibitors; moreover, ACE inhibitors increase bradykinins which may have positive effects on blood pressure and renal function. Such combination treatment has been found to be well tolerated and more effective in reducing blood pressure than either monotherapy. Positive effects on microalbuminuria or proteinuria have also been noted. Studies have shown that treatment with AT(1)-receptor blockers postpones end-stage renal disease and reduces the rate of decline in glomerular filtration rate (GFR) in patients with type 2 diabetes and nephropathy. Moreover, albuminuria was reduced to a greater extent with AT(1)-receptor blockers than with conventional antihypertensive therapy producing the same blood pressure reductions. In summary, AT(1)-receptor blockers are effective in all stages of diabetic renal disease, and have an excellent tolerability profile. Usually the side-effect profile is comparable with placebo. In certain situations, there may be a slight, readily reversible, increase in serum potassium. There may also be a slight reduction in GFR, reflecting a decrease in glomerular filtration pressure.

Are clinical endpoint benefits of angiotensin converting enzyme inhibitors independent of their blood pressure effects?

Both basic and experimental data indicate that the renin-angiotensin system through angiotensin II mediates its classic hemodynamic role, but also has a significant deleterious role in a number of cardiac, vascular, and renal disorders. Indeed, evidence indicates that angiotensin II negatively impacts endothelial function, cardiac remodeling, vessel wall hypertrophy, atherosclerosis, and progressive renal disease. Newer data point to a significant role for angiotensin II in inflammation and in inducing plasminogen activator inhibitor. This widespread negative effect can be countered by newer antihypertensive drugs, angiotensin converting enzyme inhibitors, and angiotensin receptor blockers. Both small and large clinical trials suggest a large benefit of such drugs on not only organ-specific endpoints such as renal disease or proteinuria, but on global cardiovascular events. It does appear that when blood pressure is significantly elevated, lowering blood pressure does indeed provide protection for larger endpoints such as stroke. However, at lower blood pressure levels, a hemodynamically independent effect is likely to be contributing to the positive effects. We should embrace these effects and champion them for our patients.

Prevention of cardiovascular diseases. Coronary artery disease, congestive heart failure, and stroke

Cardiovascular disease leads to significant morbidity and mortality in the older population. Results of risk reduction can be dramatic in terms of patient survival and quality of life. This article reviews evidence for cardiovascular risk factors and disease prevention in older adults. Interventions which reduce morbidity and mortality from coronary artery disease, heart failure, and cerebrovascular disease in the elderly population are examined. Attention is given to the role of cardiovascular disease in older women and in minorities, subsets not well-represented in many studies.

Drugs targeting the renin-angiotensin-aldosterone system

Effective antihypertensive therapy has made a major contribution to the reductions in the morbidity and mortality of cardiovascular disease that have been achieved since the 1960s. However, blood-pressure control with conventional drugs has not succeeded in reducing cardiovascular disease risks to levels seen in normotensive persons. Drugs that inhibit or antagonize components of the renin-angiotensin-aldosterone system are addressing this deficiency by targeting both blood pressure and related structural and functional abnormalities of the heart and blood vessels, thus preventing target-organ damage and related cardiovascular events.

Interaction between aspirin and ACE Inhibitors: resolving discrepancies using a meta-analysis

BACKGROUND

Recently, studies have attempted to explore the interaction between ACE inhibitors and aspirin (acetylsalicylic acid) when both drugs are used concomitantly to reduce mortality in patients with coronary artery disease. Results have been conflicting due, in part, to sub-optimal methods used to explore this interaction.

METHODS

We reviewed systematically all studies on mortality in patients treated with ACE inhibitors and aspirin and conducted a meta-analysis in order to explore the interaction between both drugs and resolve discrepancies. To be included, each study had to provide data on mortality of patients who received both drugs, either drug and no drug. These data were necessary to calculate the synergy index (S) and its 95% confidence interval (CI) that we used to quantify the effect due to interaction between ACE inhibitors and aspirin. After testing for heterogeneity of effects, we pooled the S values from the individual studies into one summary measure. Subsequently, we compared our results with those obtained through the most common but incorrect method of evaluating interaction. This method uses significance testing of the relative risk of mortality when a 'product term' between ACE inhibitors and aspirin is entered in a logistic regression model.

RESULTS

Eight studies met the inclusion criteria. The pooled synergy index S indicates slight but precise antagonism between ACE inhibitors and aspirin (S = 0.91; 95% CI 0.80 to 1.03). In contrast, the pooled 'product term' is not significant and would have lead to the conclusion of absence of interaction (p = 0.15).

CONCLUSION

There seems to be an antagonistic interaction between ACE inhibitors and aspirin. Former discrepancies were due to inadequate assessment of interaction. Results from the Studies on Left Ventricular Dysfunction (SOLVD) and Heart Outcome Prevention Evaluation (HOPE) trials that assessed the effect of combined administration of ACE inhibitors and aspirin were not included in this meta-analysis because those trials did not provide enough data to compute the S statistic. It is possible that results from on-going trials such as Women's Atovarstatin Trial on Cholesterol (WATCH) will shed more light on ACE inhibitor and aspirin interaction in the future.

MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20,536 high-risk individuals: a randomised placebo-controlled trial

BACKGROUND

Throughout the usual LDL cholesterol range in Western populations, lower blood concentrations are associated with lower cardiovascular disease risk. In such populations, therefore, reducing LDL cholesterol may reduce the development of vascular disease, largely irrespective of initial cholesterol concentrations.

METHODS

20,536 UK adults (aged 40-80 years) with coronary disease, other occlusive arterial disease, or diabetes were randomly allocated to receive 40 mg simvastatin daily (average compliance: 85%) or matching placebo (average non-study statin use: 17%). Analyses are of the first occurrence of particular events, and compare all simvastatin-allocated versus all placebo-allocated participants. These "intention-to-treat" comparisons assess the effects of about two-thirds (85% minus 17%) taking a statin during the scheduled 5-year treatment period, which yielded an average difference in LDL cholesterol of 1.0 mmol/L (about two-thirds of the effect of actual use of 40 mg simvastatin daily). Primary outcomes were mortality (for overall analyses) and fatal or non-fatal vascular events (for subcategory analyses), with subsidiary assessments of cancer and of other major morbidity.

FINDINGS

All-cause mortality was significantly reduced (1328 [12.9%] deaths among 10,269 allocated simvastatin versus 1507 [14.7%] among 10,267 allocated placebo; p=0.0003), due to a highly significant 18% (SE 5) proportional reduction in the coronary death rate (587 [5.7%] vs 707 [6.9%]; p=0.0005), a marginally significant reduction in other vascular deaths (194 [1.9%] vs 230 [2.2%]; p=0.07), and a non-significant reduction in non-vascular deaths (547 [5.3%] vs 570 [5.6%]; p=0.4). There were highly significant reductions of about one-quarter in the first event rate for non-fatal myocardial infarction or coronary death (898 [8.7%] vs 1212 [11.8%]; p<0.0001), for non-fatal or fatal stroke (444 [4.3%] vs 585 [5.7%]; p<0.0001), and for coronary or non-coronary revascularisation (939 [9.1%] vs 1205 [11.7%]; p<0.0001). For the first occurrence of any of these major vascular events, there was a definite 24% (SE 3; 95% CI 19-28) reduction in the event rate (2033 [19.8%] vs 2585 [25.2%] affected individuals; p<0.0001). During the first year the reduction in major vascular events was not significant, but subsequently it was highly significant during each separate year. The proportional reduction in the event rate was similar (and significant) in each subcategory of participant studied, including: those without diagnosed coronary disease who had cerebrovascular disease, or had peripheral artery disease, or had diabetes; men and, separately, women; those aged either under or over 70 years at entry; and--most notably--even those who presented with LDL cholesterol below 3.0 mmol/L (116 mg/dL), or total cholesterol below 5.0 mmol/L (193 mg/dL). The benefits of simvastatin were additional to those of other cardioprotective treatments. The annual excess risk of myopathy with this regimen was about 0.01%. There were no significant adverse effects on cancer incidence or on hospitalisation for any other non-vascular cause.

INTERPRETATION

Adding simvastatin to existing treatments safely produces substantial additional benefits for a wide range of high-risk patients, irrespective of their initial cholesterol concentrations. Allocation to 40 mg simvastatin daily reduced the rates of myocardial infarction, of stroke, and of revascularisation by about one-quarter. After making allowance for non-compliance, actual use of this regimen would probably reduce these rates by about one-third. Hence, among the many types of high-risk individual studied, 5 years of simvastatin would prevent about 70-100 people per 1000 from suffering at least one of these major vascular events (and longer treatment should produce further benefit). The size of the 5-year benefit depends chiefly on such individuals' overall risk of major vascular events, rather than on their blood lipid concentrations alone.

Physicians' interpretation of "class effects": a need for thoughtful re-evaluation

The concept of pharmacologic "class effects" exists across a broad range of medical products and is particularly pervasive with regard to cardiovascular agents. Evolution of the concept over the past two decades has shown the influence of physicians' practice patterns, pharmaceutical companies, health maintenance organizations and the Food and Drug Administration (FDA). Understanding the evolution of health care, social and economic policies, acknowledging the correction of medical misconceptions and inaccurate understanding and appreciating the emergence of new medical knowledge over the past decade should modify the clinician's viewpoint of "class effects." These revelations should signal caution in extrapolating the outcome efficacy or safety of one agent to another within a pharmacologic class. The authors urge clinicians, pharmaceutical companies, health maintenance organizations and the FDA to re-examine their concept of "class effects." An appeal is made for physicians to prescribe those pharmaceutical agents with definitive evidence of mortality and morbidity efficacy and safety established by appropriately scaled randomized clinical trials.

Quality of prereferral care in patients with chronic renal insufficiency

BACKGROUND

Appropriate care in chronic renal insufficiency (CRI) includes blood pressure and diabetes control, as well as the investigation and management of anemia, acidosis, and bone disease. There is a lack of data on the control of these parameters at the time of referral to a nephrologist. Similarly, early referral has been emphasized in the literature, yet very little published has examined current referral patterns.

METHODS

A single-center retrospective/prospective review of all new outpatient referrals to nephrologists in Halifax, Canada, in 1998 and 1999 was conducted to identify patients with CRI (serum creatinine > 1.6 mg/dL [141 micromol/L] for men or >1.2 mg/dL [106 micromol/L] for women). Quality of prereferral care was based on data from the initial clinic visit.

RESULTS

Of 1,050 charts reviewed, 411 patients met the study criteria. Twenty-six percent of patients had diabetes mellitus, 18% were referred with a calculated glomerular filtration rate less than 15 mL/min, and blood pressure was optimally controlled (<130 mm Hg systolic and <80 mm Hg diastolic) in only 24%. Only 44% of patients were administered an angiotensin-converting enzyme inhibitor. Patients were administered an average of 1.9 antihypertensive agents. Significant anemia (hemoglobin < 10 g/dL) was present in 21%, and appropriate investigations were performed in only 35% of these patients. Calcium levels less than 8.6 mg/dL (2.15 mmol/L) were found in 19% of patients, and only 14% of these patients were started on calcium supplement therapy. Phosphate levels greater than 5.0 mg/dL (1.6 mmol/L) were seen in 20% of patients, and 14% of these patients were on phosphate-binder therapy. Parathyroid hormone levels were more than five times normal values in 18% of patients, and 25% of patients had bicarbonate levels less than 23 mmol/L.

CONCLUSIONS

A significant proportion of patients referred with CRI receive inadequate prereferral care. Continuing education programs and referral guidelines must not only emphasize the importance of early referral, but also address the related consequences of CRI to delay the progression of renal disease and avoid complications.

Prognosis after acute myocardial infarction continues to improve in the reperfusion era in the community of Göteborg

BACKGROUND

The objective of this study was to compare the prognosis of nonselected patients who had an acute myocardial infarction (AMI) during 2 time periods in the thrombolytic era and to describe coronary heart disease (CHD) mortality rates in the community of Göteborg during 1990 to 1995.

METHODS

Patients aged <75 years who were hospitalized in the community of Göteborg for AMI during 1990 to 1991 (period 1) and 1995 to 1996 (period 2) were compared in terms of history, treatment for AMI, and outcome. Information on CHD mortality rates in the community of Göteborg was gathered from the National Registry of Deaths.

RESULTS

The numbers of patients in the 2 cohorts were 926 and 861, respectively. The incidence rate for AMI per 100,000 inhabitants and year was 200 for period 1 and 183 during period 2. During period 2, there was an increased use of percutaneous transluminal coronary angioplasty, coronary artery bypass grafting, angiotensin-converting enzyme inhibitors, heparin, and intravenous nitroglycerin. On the other hand, there was a decreased use of thrombolytic agents, diuretic agents, digitalis, long-acting nitrates, calcium-channel blockers, and lidocaine. The hospital case-fatality rates were 9.4% during period 1 and 6.0% during period 2 (P =.01). The adjusted risk ratio for period 2 versus period 1 was 0.65, with 95% confidence limits of 0.45 to 0.94. The mortality rate over a period of 3 years was 26.5% during period 1 and 17.8% during period 2 (P <.0001). The adjusted risk ratio for period 2 versus period 1 was 0.67, with 95% confidence limits of 0.54 to 0.82. Among inhabitants aged 30 to 74 years in the community of Göteborg, the CHD mortality rate decreased in 1995 as compared with 1990 (age-adjusted odds ratio 0.79, 95% confidence limits 0.68 to 0.92).

CONCLUSIONS

For consecutive patients aged <75 years who were hospitalized for AMI in the community of Göteborg, we found that in the thrombolytic era, major changes in medical and nonmedical treatment still took place associated with a continuing decrease in mortality rates during 3 years of follow-up. A similar reduction of CHD mortality rates was seen in the same age group within the community of Göteborg.

Peripheral arterial disease: epidemiology and drug therapy

Lower-extremity peripheral arterial disease (PAD) is common among older men and women, affecting 20%-30% of older men and women in general medicine practices. History and physical examination are insensitive measures of PAD. However, PAD can be noninvasively and reliably diagnosed in the office with the ankle-brachial index, a ratio of Doppler-recorded systolic pressures in the lower and upper extremities. An ankle-brachial index less than 0.90, consistent with PAD, is associated with increased risk of cardiovascular morbidity and mortality in addition to functional impairment. Drug therapy in PAD is directed at reducing the increased risk of cardiovascular events and improving walking impairment. Intensive atherosclerotic risk factor intervention and angiotensin-converting enzyme inhibitors are recommended for reducing cardiovascular event rates in persons with PAD. Components of an effective exercise intervention and drug therapy to reduce claudication-related walking impairment in PAD are also reviewed.

Emerging concepts in the pathophysiology and treatment of obesity-associated hypertension

The dramatic increase in the prevalence of obesity is a global phenomenon associated with increased risk of the development of cardiovascular and renal disease. Changes in renal structure and function that occur early in the development of obesity may lead to urine outflow obstruction and increased intrarenal pressure, mechanisms sufficient to shift the pressure-natriuresis relation to higher blood pressure levels. Another important alteration that may lead to hypertension with obesity is the increase in sympathetic nervous system activity. Several studies point to higher leptin levels associated with hypertension in humans, and animal data now convincingly suggest that leptin has direct central effects that increase sympathetic outflow to the kidneys, associated with increases in blood pressure. Although understanding of the pathophysiology of obesity-associated hypertension has made substantial progress during the past years, treatment of obese hypertensives remains largely empirical and clearly deserves to be addressed in larger randomized, controlled trials.

Interaction between aspirin and angiotensin-converting enzyme inhibitors: should they be used together in older adults with heart failure?

PURPOSE

To determine whether the prostacyclin-inhibiting properties of aspirin counteracts the bradykinin-induced prostacyclin-stimulating effects of angiotensin-converting enzyme (ACE) inhibitors, thereby attenuating the beneficial effects of ACE inhibitors in heart failure patients.

BACKGROUND

Most heart failure patients are older adults. Heart failure is the number one hospital discharge diagnosis of older Americans. The renin-angiotensin system plays a major role in the pathophysiology of heart failure, and ACE inhibitors play a pivotal role in the management of heart failure. Large-scale double-blind randomized trials have demonstrated the survival benefits of using ACE inhibitors in patients with heart failure associated with left ventricular systolic dysfunction. In addition to inhibiting the conversion of angiotensin I to angiotensin II, ACE inhibitors also decrease the breakdown of bradykinin. Bradykinin, a potent vasodilator, acts by stimulating formation of vasodilatory prostaglandins such as prostacyclin, whereas aspirin or acetyl salicylic acid inhibits the enzyme cyclooxygenase, which in turn decreases the production of the prostaglandins. Coronary artery disease and hypertension are the two major underlying causes of heart failure. Most heart failure patients are also on aspirin. There is evidence that aspirin at a daily dose of 80 to 100 mg prevents the synthesis of thromboxane A2 by platelets while relatively sparing the synthesis of prostacyclin in the vascular endothelium. Aspirin at a daily dose of 325 mg has significant inhibitory effects on the vasodilatory prostacyclin synthesis. Studies have demonstrated that, in heart failure patients, low-dose aspirin has no adverse effect on hemodynamic, neurohumoral, or renal functions. Whether the prostacyclin-inhibiting effects of aspirin attenuate some of the beneficial effects of ACE inhibitors mediated by prostacyclin stimulation in heart failure patients is currently unknown.

METHODS

Data from large clinical trials investigating the interaction between aspirin and ACE inhibitors were analyzed to determine the effect of aspirin on the vasodilatory actions of ACE inhibitors in heart failure patients, and the results were analyzed on the basis of theoretical and laboratory findings. The studies included are the Studies of Left Ventricular Dysfunction (SOLVD) (N=6,797), the Cooperative New Scandinavian Enalapril Survival Study II (CONSENSUS II) (N=6,090), the Captopril and Thrombolysis Study (CATS) (N=296), and another study involving 317 subjects. The data from these clinical trials investigating the interaction between aspirin and ACE inhibitors included 13,470 subjects. Most of the subjects received aspirin. In the SOLVD study, subjects received aspirin or dipyridamole. Subjects were followed up for an average of about 6 years.

RESULTS

In the SOLVD study, subjects were followed up for 41.1 months in the treatment trial and 37.4 months in the prevention trial. Patients who received aspirin or dipyridamole at baseline did not receive the survival benefits of enalapril, whereas patients who received enalapril did not receive the survival benefits of aspirin. In a rather small study of 317 subjects with left ventricular systolic dysfunction (ejection fraction <35%) who were followed up for a relatively longer period of time (5.7 years), the favorable long-term prognosis of patients receiving aspirin was independent of receipt of an ACE inhibitor. A retrospective subgroup analysis of data from the CONSENSUS II study demonstrated that the 6-month mortality rate of patients with acute myocardial infarction (MI) who received enalapril and aspirin was higher than the combined mortality rates of patients receiving enalapril or aspirin alone. This strong interaction between aspirin and the ACE inhibitor enalapril suggests that the survival benefit of enalapril was significantly lower in patients also taking aspirin than in those taking enalapril alone. This interaction was not associated with other nonfatal major events. In the CATS study, use of low-dose aspirin (80 or 100 mg) did not attenuate beneficial effects of captopril (immediate and 1-year follow up) after acute MI.

CONCLUSION

There is a theoretical possibility that the negative interaction between ACE inhibitors and aspirin may reduce the beneficial effects of ACE inhibitors in patients with heart failure, but the information obtained from the existing databases is limited by the retrospective nature of the analyses and does not establish the association definitively. Double-blind randomized controlled trials should be conducted to determine whether such a negative interaction indeed exists.

Angiotensin II type 1 and 2 receptors in conduit arteries of normal developing microswine

OBJECTIVE

To identify vascular cells capable of responding to angiotensin II (Ang II) generated in conduit arteries, we examined the Ang II type 1 receptor (AT1R) and Ang II type 2 receptor (AT2R) in the thoracic aorta (TA) and abdominal aorta (AA) and branches in 90-day fetal, 3-week postnatal, and 6-month adult microswine.

METHODS AND RESULTS

By autoradiography ((125)I-[Sar(1)Ile(8)]-Ang II with or without AT1R- or AT2R-selective analogues or (125)I-CGP 42112), there were striking rostrocaudal differences in (1) AT2R binding at all ages (prominent in AA wall and branches, sparse in TA wall and branches) and (2) a non-AT2R binding site for CGP 42112 (consistently evident in postnatal TA and branches but absent in AA and branches). Furthermore, patterns of AT2R distribution in infradiaphragmatic arteries were developmentally distinct. In fetal AAs, high-density AT2Rs occupied the inner 60% of the medial-endothelial wall. In postnatal AAs, AT2Rs were sparse in the medial-endothelial wall but prominent in a circumferential smooth muscle alpha-actin-negative cell layer at the medial-adventitial border, occupying approximately 20% to 25% of the AA cross-sectional area. AT1R density in the TA and AA medial-endothelial wall increased with age, whereas AT2R density decreased after birth.

CONCLUSIONS

A novel AT2R-positive cell layer confined to postnatal infradiaphragmatic arteries physically links adventitial and medial layers, appears optimally positioned to transduce AT2R-dependent functions of local Ang II, and suggests that adventitial Ang II may elicit regionally distinct vascular responses.

New horizons for stroke prevention: PROGRESS and HOPE

Inhibitors of angiotensin-converting enzyme (ACE) act by blocking the conversion of angiotensin I to angiotensin II, which is catalysed by this enzyme. ACE inhibitors also prevent the breakdown of bradykinin, a potent vasodepressor agent, and prevent the effects of angiotensin II, which include increase in blood pressure, peripheral vasoconstriction, and stimulation of aldosterone secretion from the adrenal cortex. Physiological and pathological studies have shown that ACE inhibitors have beneficial effects, such as increasing vascular compliance, regression of periarteriolar collagen area, improvement of coronary reserve, and regression of resistance-artery structure and left-ventricular hypertrophy. Information about the role of ACE inhibitors in stroke prevention has been limited. This review explores the epidemiological evidence for hypertension as a risk factor for stroke, a national guideline for blood-pressure control to reduce the incidence of stroke and cardiovascular disease, the findings of two recently published clinical trials on prevention of stroke and cardiovascular disease after administration of ACE inhibitors (PROGRESS and HOPE), and the implications of the findings for redefinition of future management of blood-pressure control for individuals at high risk of stroke and cardiovascular disease. The PROGRESS and HOPE trials have shown that ACE inhibitors have an important role in the prevention of stroke and cardiovascular-disease events.

Guideline-discordant care in acute myocardial infarction: predictors and outcomes

OBJECTIVES

To determine (i) factors which predict whether patients hospitalised with acute myocardial infarction (AMI) receive care discordant with recommendations of clinical practice guidelines; and (ii) whether such discordant care results in worse outcomes compared with receiving guideline-concordant care.

DESIGN

Retrospective cohort study.

SETTING

Two community general hospitals.

PARTICIPANTS

607 consecutive patients admitted with AMI between July 1997 and December 2000.

MAIN OUTCOME MEASURES

Clinical predictors of discordant care; crude and risk-adjusted rates of inhospital mortality and reinfarction, and mean length of hospital stay.

RESULTS

At least one treatment recommendation for AMI was applicable for 602 of the 607 patients. Of these patients, 411(68%) received concordant care, and 191 (32%) discordant care. Positive predictors at presentation of discordant care were age > 65 years (odds ratio [OR], 2.5; 95% CI, 1.7-3.6), silent infarction (OR, 2.7; 95% CI, 1.6-4.6), anterior infarction (OR, 2.5; 95% CI, 1.7-3.8), a history of heart failure (OR, 6.3; 95% CI, 3.7-10.7), chronic atrial fibrillation (OR, 3.2; 95% CI, 1.5-6.4); and heart rate >/= 100 beats/min (OR, 2.1; 95% CI, 1.4-3.1). Death occurred in 12.0% (23/191) of discordant-care patients versus 4.6% (19/411) of concordant-care patients (adjusted OR, 2.42; 95% CI, 1.22-4.82). Mortality was inversely related to the level of guideline concordance (P = 0.03). Reinfarction rates also tended to be higher in the discordant-care group (4.2% v 1.7%; adjusted OR, 2.5; 95% CI, 0.90-7.1).

CONCLUSIONS

Certain clinical features at presentation predict a higher likelihood of guideline-discordant care in patients presenting with AMI. Such care appears to increase the risk of inhospital death.

Treating hypertension in patients with diabetes

The coexistence of hypertension and diabetes synergistically increases the risk of cardiovascular and renal diseases. Although aggressive blood pressure reduction can decrease the rate of cardiovascular events in general, blockade of the renin-aldosterone-angiotensin system is a particularly effective target for antihypertensive treatment that may provide additional benefits for patients with diabetes. This article details evidence for blood pressure targets and antihypertensive drug choice in hypertensive patients with diabetes.

Renoprotective effects of losartan in diabetic nephropathy: interaction with ACE insertion/deletion genotype?

BACKGROUND

The beneficial short- and long-term renoprotective effects of angiotensin I-converting enzyme (ACE) inhibition are lower in albuminuric diabetic patients homozygous for the deletion compared to the insertion polymorphism of the ACE gene. In an attempt to overcome this interaction, we evaluated the short-term renoprotective effect in diabetic nephropathy of the angiotensin II receptor antagonist losartan in patients homozygous for the insertion or the deletion allele.

METHODS

Fifty-four hypertensive type 1 diabetic patients with diabetic nephropathy homozygous for the insertion (I; N = 26) or the deletion (D; N = 28) allele of the ACE/ID polymorphism were included. After four weeks of washout, the patients received losartan 50 mg daily followed by 100 mg in two treatment periods each lasting two months. Patients and investigators were blinded to ACE genotypes. At baseline and in the end of the treatment periods, 24-hour blood pressure, albuminuria and glomerular filtration rate values were determined.

RESULTS

At baseline, blood pressure, albuminuria and glomerular filtration rate (GFR) values were similar in the two genotype groups [II vs. DD, 1134 (238 to 5302) vs. 1451 (227 to 8129) mg/24 h, median (range); 156/82 (17/9) vs. 153/80 (17/11) mm Hg, mean (SD); and 86 (22) vs. 88 (24) mL/min/1.73 m2, respectively]. Both doses of losartan significantly lowered blood pressure, albuminuria, and GFR (P < 0.05 vs. baseline). Losartan 100 mg was more effective than 50 mg in reducing albuminuria, 51% (95% CI; 40 to 61) versus 33% (23 to 42), respectively (P < 0.01). No differences in the impact of losartan between the II and DD groups were observed: Losartan 100 mg lowered systolic/diastolic blood pressure by 12/6 and 10/4 mm Hg, whereas albuminuria decreased by 55% (35 to 68) and 46% (28 to 61), in the II and DD groups, respectively (P = NS).

CONCLUSION

Our data suggest that losartan offers similar short-term renoprotective and blood pressure lowering effects in albuminuric hypertensive type 1 diabetic patients with the ACE II and DD genotypes. However, the long-term renoprotective effects remain to be evaluated.

Risk-benefit assessment of angiotensin II receptor antagonists

Inhibiting the renin-angiotensin-aldosterone system through the use of angiotensin-converting enzyme (ACE) inhibitors has proven very useful in the treatment of hypertension, congestive heart failure (CHF) and progressive renal failure. More recently, agents that directly block the angiotensin II Type 1 (AT(1)) receptor--angiotensin II receptor antagonists (AIIRAs)--have been developed. These agents are thought to have a more specific mechanism of action since they do not affect other hormone systems as do the ACE inhibitors. Whether such specificity results in a different efficacy profile is still being determined. However, these drugs are extremely well-tolerated and very safe. AIIRAs are effective in the reduction of both systolic and diastolic blood pressure and compare favourably to other classes of agents. Recent results indicate that at least one AIIRA has a favourable effect on stroke in hypertensive patients with left ventricular hypertrophy. Additional studies with other members of the class will provide further information on similar outcomes. In CHF patients, ACE inhibitors remain the drug of choice and AIIRAs are best utilised in patients who cannot tolerate an ACE inhibitor or in those receiving an ACE inhibitor who cannot tolerate a beta-blocker and need additional therapy. AIIRAs are effective in slowing the progression of renal failure in patients with Type II diabetes and may be effective in other proteinuric conditions. Whether they are more or less effective than ACE inhibitors is unknown. Overall, AIIRAs represent an important addition to the armamentarium of cardiovascular therapies with an excellent safety record and an emerging profile of utility in multiple cardiovascular conditions.

Nitric oxide and atherosclerotic lesion progression: an overview

There is a growing interest regarding the complex pathophysiological relationship between nitric oxide (NO) and the development of atherosclerosis. The endothelial damage induced by atherogenesis may lead to the reduction in concentration or activity both of inducible and endothelial NO synthase with subsequent impaired release of NO. Moreover, impaired NO diffusion from endothelium to vascular smooth muscle cells is followed by decreased sensitivity to its vasodilator action. Finally, an important mechanism would be a local enhanced degradation of NO by increased generation of reactive oxygen species and other free radicals with subsequent cascade of oxidation-sensitive mechanisms in the arterial wall. Therefore, one target for new drugs should be the restoration of NO-mediated signaling pathways in atherosclerotic arteries. Such novel therapeutic strategies may include administration of L-arginine, the precursor of NO, as well as antioxidants, NO donors, and tissue-specific gene-therapy approaches.

Impact of availability and use of coronary interventions on the prescription of aspirin and lipid lowering treatment after acute coronary syndromes

BACKGROUND

It has been suggested that patients undergoing acute intervention for coronary syndromes may not receive adequate secondary prevention.

OBJECTIVE

To analyse the impact of availability and use of coronary interventions on the prescription of secondary prevention after acute coronary syndromes.

DESIGN

Analysis of a prospective multicentre register of patients admitted to hospital for acute coronary syndromes.

SETTING

A 1999 pan-European survey in 390 hospitals.

PATIENTS

3092 patients admitted to hospital with acute coronary syndromes (including 777 for ST elevation myocardial infarction within 12 hours of onset).

MAIN OUTCOME MEASURES

Rates of prescription of aspirin and lipid lowering agents.

RESULTS

Performance of coronary angiography and percutaneous coronary interventions (PCI) during the hospital stay were independent predictors of prescription of aspirin at discharge (odds ratio (OR) 1.29 and 1.89, p = 0.053 and p < 0.0001, respectively). Lipid lowering agents were prescribed more often on discharge in patients admitted to hospitals with catheterisation laboratories than without (for infarction with ST elevation, 45% v 40% (NS); for other acute coronary syndromes, 46% v 36%; p < 0.05). Prescription rates were higher among patients undergoing coronary angiography or PCI than in those treated conservatively (for infarction with ST elevation, 49%, 53%, and 39%, p < 0.05; for other acute coronary syndromes, 50%, 54%, and 34%, p < 0.05). Logistic regression analysis showed that PCI was an independent predictor of prescription of lipid lowering agents at discharge (OR 1.48, p < 0.0002).

CONCLUSIONS

Contrary to expectations, invasive procedures for acute coronary syndromes are associated with higher rates of prescription of pharmacological secondary prevention.

The need for a national infrastructure to improve the rational use of therapeutics

The current medical care environment has created expectations that exceed its capabilities, one effect of which has been an increasing awareness of lapses in the quality of healthcare, including medical errors. As more new therapies reach clinical application, the expectations on the part of the public are unlikely to lessen, and yet the ability to assure patients that the benefits of these therapies are known, and that they are without serious side-effects or untoward consequences, eludes the healthcare system. Based on initial experience with a new federal program, the Centers for Education and Research on Therapeutics (CERTs), we propose a national approach to therapeutics education and research, through a public-private partnership that involves academic medical centers, the federal government, industry, and the public. Through a concerted approach, we believe that significant gaps in our understanding of key issues in therapeutics and our ability to educate practitioners, policy makers, and consumers can be significantly enhanced in a manner that could not be achieved without a coordinated approach.

Combining renin-angiotensin-aldosterone system blockade with diuretic therapy for treatment of hypertension

The rationale for using angiotensin-converting enzyme inhibitors (ACE-I) or angiotensin receptor blockers (ARBs) in combination with thiazide diuretic therapy has centred formerly around antihypertensive synergy and counter-balancing adverse metabolic effects, particularly on potassium homeostasis. However, two recent landmark clinical trials that included high-risk hypertensive patients have now provided an evidence base for this form of combination therapy by demonstrating the efficacy of perindopril/indapamide and losartan/ hydrochlorothiazide in reducing vascular morbidity and mortality, a proportion of the benefit being unaccounted for by blood pressure reduction alone. Several unresolved issues remain concerning class effects versus specific drug effects, optimal dosing, potential differences in efficacy between ACE-I and ARBs, whether elderly mild hypertensives benefit from this form of combination therapy, and the possibility that the optimal regimen may be a triple combination of ACE-I, ARB and thiazide diuretic. These issues will be resolved by ongoing and future major endpoint trials in hypertension.

The cost-effectiveness of ramipril in the treatment of patients at high risk of cardiovascular events: a Swedish sub-study to the HOPE study

OBJECTIVE

To evaluate if long-term treatment with ramipril is cost-effective in patients at high risk of cardiovascular events.

DESIGN

Randomized double-blind and placebo controlled. Information was gathered prospectively for a number of direct medical, direct nonmedical and indirect costs.

SETTING AND SUBJECT

This is a sub-study to the Heart Outcomes Prevention Evaluation (HOPE) study performed in Swedish patients. All Swedish centres (19; n= 554) were invited to take part and 18 centres agreed to do so (n=537). The patients were managed in a specialist setting with a mean follow-up period of 4.5 years. Main outcome measures. The number of life-years saved was derived from the global HOPE study (n=9297) and subsequently the estimated life expectancy of those who completed the clinical study alive was added to the calculation. Direct medical costs related to cardiovascular disease only were considered in the primary analysis, whilst all kinds of costs and costs for all kinds of diseases were included in subsequent analyses. The cost of added years of life, according to the future cost method, was included in sensitivity analyses.

RESULTS

The cost per life-year gained was SEK 16 600 (Euro 1940) when direct medical costs for cardiovascular reasons only were considered and SEK 45 400 (Euro 5300) when direct medical costs for all diseases were considered. The corresponding costs when direct nonmedical and indirect cost were added to the estimate were SEK 16 100 (Euro 1880) and SEK 54 600 (Euro 6380), respectively. When the future cost method was applied, the cost per life-year gained was SEK 208 300 (Euro 24 300).

CONCLUSION

Ramipril is highly cost-effective in the treatment of patients at high risk of cardiovascular events.

The importance of validating the diagnosis of coronary heart disease when measuring secondary prevention: a cross-sectional study in general practice

PURPOSE

To compare levels of recorded risk factors and drug treatment between patients with validated and non-validated diagnoses of coronary heart disease (CHD) in Northern Ireland.

METHODS

Patients with a nitrate prescription in the previous year or a CHD Read code were identified from computer records of 25 practices, stratified by partnership size and area board. Computer and paper records of a random sample of 10% of these were searched for specified criteria to validate the diagnosis of CHD. The diagnosis was considered valid if the patient was found to have one or more positive investigations for CHD. Records of blood pressure, cholesterol, blood sugar, body mass index and drugs prescribed were taken into account.

RESULTS

The combined practice population was 151,071; 7338 (4.86%) were identified by the computer search as meeting the defined entry criteria for CHD. Among the 10% random sample the diagnosis of CHD could not be validated for 36.5% (265/727). Significantly more patients with a validated than non-validated diagnosis had recorded cholesterol levels below 5.0 mmol/l (55.8 vs. 34.5%, p < 0.001) and were prescribed aspirin (75.3 vs. 40.8%, p < 0.001), beta-blockers (51.5 vs. 28.3%, p < 0.001), angiotensin-converting-enzyme inhibitors (29.2 vs. 15.5%, p < 0.001) and lipid-lowering drugs (50.9 vs. 23.0%, p < 0.001). A recent nitrate prescription had a higher predictive value for validated CHD than a Read code for CHD alone (71.2 vs. 53.1%, p < 0.001). No other significant differences were found between the two groups regarding the extent or levels of recorded risk factors.

CONCLUSIONS

Patients with a validated diagnosis of CHD appear to be better managed than those whose diagnosis has not been confirmed. Validation of diagnosis has important implications for assessing the provision of secondary prevention and for clinical governance.

The practical aspects of combination therapy with angiotensin receptor blockers and angiotensin-converting enzyme inhibitors

Angiotensin-converting enzyme (ACE) inhibitors and/or angiotensin receptor blockers (ARBs) are widely prescribed for the management of hypertension. ACE inhibitors (ACE-I) and, more recently, ARBs have an established track record of success in the treatment of congestive heart failure (CHF), proteinuric renal disease and most recently the hypertensive patient with a high cardiac-risk profile. The individual success of each of these drug classes has fuelled speculation that given together the overall effect of both would exceed that of either given alone. This premise, although biologically plausible, has yet to be proven in a convincing enough fashion to support the routine use of these two drug classes in combination. Additional clarifying studies are needed to establish whether specific patient subsets exist that might benefit from such combination therapy.

ACE gene insertion/deletion polymorphism associated with 1998 World Health Organization definition of metabolic syndrome in Chinese type 2 diabetic patients

OBJECTIVE

Because ACE insertion/deletion (I/D) polymorphism has been shown to be associated with diabetes, hypertension, coronary artery diseases, and diabetic nephropathy, and because plasma ACE concentration has been found to be associated with plasma triglyceride and total cholesterol levels in patients with type 2 diabetes, the goal of this study was to investigate whether ACE gene I/D polymorphism is associated with metabolic syndrome in Chinese subjects with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 711 patients with type 2 diabetes and 750 control subjects were studied. The ACE I/D polymorphism was determined by PCR. The definition and criteria of metabolic syndrome used in this study matched those proposed in the 1998 World Health Organization classification.

RESULTS

Of 711 patients with type 2 diabetes, 534 (75.1%) fulfilled the criteria for metabolic syndrome. The prevalence of metabolic syndrome in control subjects with II, ID, and DD genotype was 9.4, 11.5, and 15.4%, respectively, and in patients with type 2 diabetes, it was 68.6, 79.2, and 86.1%, respectively. The ACE I/D polymorphism was significantly associated with the syndrome in patients with type 2 diabetes (P = 0.001). When pooling the control subjects with diabetic patients, the prevalence of metabolic syndrome in the whole study group with II, ID, and DD genotype was 37.9, 44.5, and 51.0%, respectively, and ACE I/D polymorphism was still significantly associated with metabolic syndrome (P = 0.003). Diabetic patients with DD genotype were also found to have a higher prevalence of dyslipidemia (II/ID/DD = 43.1/53.1/65.8%, P < 0.001) and albuminuria (36.0/44.6/50.6%, P = 0.018) and to have higher serum triglyceride levels (II, ID, and DD = 155 +/- 114, 170 +/- 140, and 199 +/- 132 mg/dl, respectively, P < 0.05). Control subjects with DD genotype were also found to have a higher prevalence of albuminuria or more advanced nephropathy (II/ID/DD = 5.7/14.0/15.4%, P = 0.001), whereas the prevalence of dyslipidemia was not found to be statistically different in the control group. When pooling control with diabetic subjects, ACE genotype could still be significantly associated with dyslipidemia (II/ID/DD = 34.7/41.3/52.2%, P < 0.001) and albuminuria or more advanced nephropathy (20.3/28.9/33.1%, P < 0.001). Diabetic patients with metabolic syndrome were found to have higher serum uric acid levels than those without metabolic syndrome (6.4 +/- 1.8 vs. 5.3 +/- 1.4 mg/dl, P < 0.01).

CONCLUSIONS

The ACE I/D polymorphism was found to be associated with metabolic syndrome in Chinese patients with type 2 diabetes. This finding may provide genetic evidence to explain the clustering of metabolic syndrome and suggests that the renin-angiotensin system is involved in the pathophysiology of metabolic derangement in patients with type 2 diabetes.

Ethnicity affects vasodilation, but not endothelial tissue plasminogen activator release, in response to bradykinin

Previous studies indicate that the vasodilator response to bradykinin (BK) and other endothelium-dependent and -independent agonists is decreased in black Americans compared with white Americans. The purpose of the present study was to determine the effect of ethnicity on fibrinolytic function in humans. Graded doses of BK (100, 200, and 400 ng/min), acetylcholine (15, 30, and 60 microg/min; N=20), or methacholine (3.2, 6.4, 12.8 microg/min; N=20), and sodium nitroprusside (0.8, 1.6, and 3.2 microg/min) were infused via brachial artery in 19 white and 21 black age-matched normotensive subjects. Forearm blood flow (FBF) was measured by plethysmography, and venous and arterial samples were collected for tissue plasminogen activator (tPA) antigen. Compared with whites (increase in FBF from 3.7+/-0.5 to 23.9+/-2.5 mL x min(-1) x 100 mL(-1)), blacks (increase in FBF from 2.8+/-0.3 to 15.2+/-1.9 mL x 100 mL(-1) x min(-1)) exhibited a blunted FBF response to BK (P=0.035). Responses to sodium nitroprusside and methacholine or acetylcholine were similarly decreased. In contrast, there was no effect of ethnicity on net tPA antigen release in response to BK (increase from -0.2+/-0.4 to 67.3+/-15.2 ng x min(-1) x 100 mL(-1) in blacks; from 0.04+/-0.9 to 65.9+/-13.6 ng x min(-1) x 100 mL(-1) in whites). Thus, ethnicity significantly influenced the relationship between the flow and tPA release responses to BK (P=0.037). These data suggest that the BK-dependent alterations in vascular fibrinolytic function are preserved in black Americans compared with white Americans.

The frequent need for three or more drugs to treat essential hypertension. What evidence for optimal combinations?

Treatment of high blood pressure (BP) reduces the risk of death and morbidity from stroke and coronary heart disease. There is accumulating evidence from large outcome studies that support a move towards lower treatment targets in hypertensives, particularly for those with concomitant risk factors or evidence of established target organ damage. At present, the achieved rates for BP control in the UK are very poor. Amongst the many possible reasons for poor BP control is the under utilisation of effective drug combinations. This article addresses the rationale for two and three drug combination therapy in hypertension and reviews the trial evidence for efficacy of combinations.

Obesity, atherosclerosis and the vascular endothelium: mechanisms of reduced nitric oxide bioavailability in obese humans

It is now well established that obesity is an independent risk factor for the development of coronary artery atherosclerosis. The maintenance of vascular homeostasis is critically dependent on the continued integrity of vascular endothelial cell function. A key early event in the development of atherosclerosis is thought to be endothelial cell dysfunction. A primary feature of endothelial cell dysfunction is the reduced bioavailability of the signalling molecule nitric oxide (NO), which has important anti atherogenic properties. Recent studies have produced persuasive evidence showing the presence of endothelial dysfunction in obese humans NO bioavailability is dependent on the balance between its production by a family of enzymes, the nitric oxide synthases, and its reaction with reactive oxygen species. The endothelial isoform (eNOS) is responsible for a significant amount of the NO produced in the vascular wall. NO production can be modulated in both physiological and pathophysiological settings, by regulation of the activity of eNOS at a transcriptional and post-transcriptional level, by substrate and co-factor provision and through calcium dependent and independent signalling pathways. The present review discusses general mechanisms of reduced NO bioavailability including factors determining production of both NO and reactive oxygen species. We then focus on the potential factors responsible for endothelial dysfunction in obesity and possible therapeutic interventions targetted at these abnormalities.

Mature adipocytes inhibit in vitro differentiation of human preadipocytes via angiotensin type 1 receptors

Recent studies suggest that angiotensin II (Ang II) plays a role in the adipogenesis of murine preadipocytes. Here, we examined the role of Ang II for the differentiation of primary cultured human preadipocytes. Preadipocytes were isolated from human adipose tissue and stimulated to differentiate. Quantitation of gene expression during adipogenesis was performed for renin-angiotensin system (RAS) genes. The influence of the RAS on adipogenic differentiation was investigated by addition of either angiotensinogen (AGT), Ang II, or angiotensin receptor antagonists to the differentiation medium. We also examined the influence of adipocytes on adipogenesis by co-culture experiments. Expression of the RAS genes AGT, renin, angiotensin-converting enzyme, and Ang II type 1 receptor increased during adipogenesis. Stimulation of the Ang II type 1 receptor by Ang II reduced adipose conversion, whereas blockade of this receptor markedly enhanced adipogenesis. Adipocytes were able to inhibit preadipocyte differentiation in the co-culture, and this effect was abolished by blockade of the Ang II type 1 receptor. This finding points to a functional role of the RAS in the differentiation of human adipose tissue. Because AGT secretion and Ang II generation are characteristic features of adipogenesis, we postulate a paracrine negative-feedback loop that inhibits further recruitment of preadipocytes by maturing adipocytes.

Cardiovascular risk factors in diabetic patients with hypertension

Individuals with diabetes mellitus have cardiovascular disease (CVD) mortality comparable to nondiabetics who have suffered a myocardial infarction or stroke. Aggressive management of risk factors such as hypertension, dyslipidemia, and platelet dysfunction in persons with diabetes has been shown to reduce morbidity and mortality in prospective randomized controlled clinical trials. Accordingly, there are national mandates to lower blood pressure to less than 130/85 mm Hg, reduce low-density lipoprotein cholesterol to less than 100 mg/dL, and institute aspirin therapy in adult patients with diabetes. Although not definitively shown to reduce CVD, there are also recommendations to control the level of glycemia, as well. This article discusses CVD risk factors in the diabetic patient with hypertension.

Renin-angiotensin system antagonism and lipid-lowering therapy in cardiovascular risk management

The renin-angiotensin system (RAS) and dyslipidaemia have been shown to be involved in the genesis and progression of atherosclerosis. Manipulation of the RAS has been effective in modifying human coronary artery disease progression. Similarly, the 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors or statins have been shown to reduce cholesterol and lower cardiovascular events in primary and secondary prevention trials in coronary artery disease. In addition to their primary mode of action, statins and blockers of the RAS possess common additional properties that include restoration of endothelial activity and inhibition of cellular proliferation. This article reviews the current data on the common properties of these classes of drugs in which the beneficial effects extend beyond their antihypertensive and lipid-lowering properties.