Effect of enalapril on myocardial infarction and unstable angina in patients with low ejection fractions

Perindopril augments ecto-ATP diphosphohydrolase activity and enhances endothelial anti-platelet function in human umbilical vein endothelial cells

OBJECTIVES

Recent clinical trials have demonstrated that angiotensin-converting enzyme inhibitors (ACEIs) reduce thrombotic events by unknown mechanisms in patients with atherosclerotic cardiovascular diseases.

DESIGN

We studied the in-vitro effects of perindopril, an ACEI, on the ability of human umbilical vein endothelial cells (HUVEC) to inhibit platelet aggregation.

METHODS

Platelet aggregation in the presence of HUVEC and endothelial surface expression and activities of ecto-ATP diphosphohydrolase (ecto-ADPase), CD39, were determined. The capability of HUVEC to release prostacyclin and nitric oxide (NO) was also investigated.

RESULTS

Perindoprilat (an active metabolite of perindopril) significantly enhanced the surface expression and activities of ecto-ADPase and prostacyclin release, resulting in enhancement of ability to inhibit platelet aggregation by HUVEC. These effects of perindoprilat were also observed in HUVEC activated by tumour necrosis factor (TNF)-alpha, which increased the expression of intracellular adhesion molecule-1 (ICAM-1), CD54, and, despite up-regulation of prostacyclin release, attenuated endothelial anti-platelet properties by decreasing ecto-ADPase activity. Perindoprilat partially restored this capability, but failed to reduce enhanced expression of ICAM-1. By contrast, the role of NO as a platelet inhibitor appeared minimal in HUVEC. Candesartan, an angiotensin II receptor (AT(1)) blocker, did not affect endothelial anti-platelet property.

CONCLUSIONS

Perindoprilat was found to augment endothelial capability to inhibit platelet aggregation by increasing ecto-ADPase activity and prostacyclin release in HUVEC. This beneficial effect of perindoprilat appeared to be preserved in the activated cells exposed to TNF-alpha, although no evidence was found to support that it could reverse the inflammation process induced by cytokines.

Modulating atherosclerosis through inhibition or blockade of angiotensin

Angiotensin-convertng enzyme (ACE) inhibitors are well recognized for their benefits in treating hypertension and congestive heart failure and preventing postmyocardial infarction heart failure or left ventricular (LV) dysfunction. Recently, blockade of the angiotensin II type 1 (AT1) receptor was shown to reduce cardiovascular events in hypertensive subjects with LV hypertrophy. Several lines of evidence are now converging to show that ACE inhibitors may affect the atherosclerotic process itself. Emerging clinical data indicate that angiotensin-receptor blockers (ARBs) may possibly modulate atherosclerosis as well. The antiatherogenic properties of ACE inhibitors and ARBs may derive from inhibition or blockade of angiotensin II, now recognized as an agent that increases oxidative stress.Angiotensin-converting enzyme inhibition and angiotensin-receptor blockade also increase endothelial nitric oxide formation, which improves endothelial function. In contrast to the effects of ARBs, the vascular effects of ACE inhibitors may, in part, be mediated by an increase in bradykinin. This article reviews some of the biologic mechanisms whereby ACE inhibitors and ARBs may modulate atherosclerosis.

Pharmacological treatment of patients with peripheral arterial disease

Atherosclerosis is a disease process that affects the coronary, cerebral and peripheral arterial circulation. While great emphasis has been placed on the aggressive pharmacological management of coronary artery disease, less attention has been paid to the pharmacological management of peripheral vascular disease, despite its significant morbidity and mortality. The purpose of medical management in peripheral arterial disease is to relieve symptoms of claudication and to prevent thrombotic vascular events. These goals are best achieved through aggressive risk factor modification and pharmacotherapy. Risk factor modification includes smoking cessation, adequate control of blood pressure and cholesterol, as well as aggressive glycaemic control in patients with diabetes mellitus. Antiplatelet therapy and relief of claudication is also achieved through pharmacotherapy. With aggressive risk factor modification and adequate pharmacotherapy, patients with peripheral arterial disease can have an improved quality of life as well as prolonged survival.

Blood coagulation in patients with chronic heart failure: evidence for hypercoagulable state and potential for pharmacological intervention

Incidence data on thromboembolism in patients with heart failure (which may include stroke, peripheral embolism, pulmonary embolism) are limited but provide a general population range from 1-5 cases per 1000 each year, increasing with age to more than 30 cases per 1000 each year among people aged 75 years or older. However, the incidence of thromboembolism varied depending very much on what was being investigated in each of these studies. Data from subgroup analysis of the larger heart failure trials would seem to support this incidence data, although there is very little true epidemiological data and no randomised, controlled trial has been designed to specifically investigate thromboembolism in patients with heart failure. The pathophysiology of heart failure is complex. There are many well recognised factors which are associated with thrombosis in heart failure patients, such as vascular abnormalities, increased coagulability and impaired blood flow. In the past 50 years many studies have been performed to investigate if oral anticoagulation is of benefit for the prevention of thromboembolism in patients with heart failure. The use of warfarin therapy for heart failure patients has been a controversial subject. Warfarin does have a role to play in patients with myocardial infarction and those with atrial fibrillation. Furthermore, in patients with congestive heart failure secondary to coronary artery disease, warfarin reduces the occurrence of nonfatal myocardial infarction and, therefore, may reduce the chances of progression to heart failure. It has also been shown that warfarin reduces the risk of thromboembolic strokes in patients recovering from myocardial infarction. At present, there is a lack of randomised data, and the incidence of bleeding complications in patients with heart failure has caused a decrease in the use of oral anticoagulants for the prevention of thrombosis. This review summarises the incidence, potential mechanism and therapeutic approaches for management of thromboembolism in heart failure.

Effect of enalapril on 12-year survival and life expectancy in patients with left ventricular systolic dysfunction: a follow-up study

BACKGROUND

In the studies of left ventricular dysfunction (SOLVD), enalapril reduced mortality in patients with symptomatic but not asymptomatic left ventricular systolic dysfunction during the trial. We did a 12-year follow-up of SOLVD to establish if the mortality reduction with enalapril among patients with heart failure was sustained, and whether a subsequent reduction in mortality would emerge among those with asymptomatic ventricular dysfunction.

METHODS

Of the 6797 patients previously enrolled in the SOLVD prevention and treatment trials, we ascertained the subsequent vital status of 5165 individuals who were alive when the trials had been completed. Follow-up was done through direct contacts in Belgium and linkages with national death registries and federal beneficiary or historic tax summary files in the USA and Canada.

FINDINGS

Follow-up was 99.8% (6784/6797) complete. In the prevention trial, 50.9% (1074/2111) of the enalapril group had died compared with 56.4% (1195/2117) of the placebo group (generalised Wilcoxon p=0.001). In the treatment trial, 79.8% (1025/1285) of the enalapril group had died compared with 80.8% (1038/1284) of the placebo group (generalised Wilcoxon p=0.01). The reductions in cardiac deaths were significant and similar in both trials. When data for the prevention and treatment trials were combined, the hazard ratio for death was 0.90 for the enalapril group compared with the placebo group (95% CI 0.84-0.95, generalised Wilcoxon p=0.0003). Enalapril extended median survival by 9.4 months in the combined trials (95% CI 2.8-16.5, p=0.004).

INTERPRETATION

Treatment with enalapril for 3-4 years led to a sustained improvement in survival beyond the original trial period in patients with left ventricular systolic dysfunction, with an important increase in life expectancy.

Prevention and management of chronic heart failure in patients at risk

The prevalence and incidence of chronic heart failure (HF) have now reached epidemic proportions. However, the issue of the prevention of HF has been raised only recently. New US guidelines have introduced a new classification system that includes 4 categories: patients at risk, patients with asymptomatic left ventricular dysfunction, patients with symptomatic HF, and those with refractory HF. Because coronary artery disease is the major cause of HF, its risk factors are also those of HF. Hypertension favors the development of HF through accelerated atherosclerosis and increased left ventricular wall stress and hypertrophy. Left ventricular hypertrophy is also a powerful risk factor for HF, independent of blood pressure. Angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, and diuretics are the antihypertensive agents that have been associated with favorable effects in patients with overt HF. Therefore, they may be preferred in the prevention of this syndrome. Diabetes is the most frequent noncardiac comorbidity of HF and is independently associated with an increased risk. Normalization of glycemic and glycosylated hemoglobin levels is a desirable goal of treatment. However, no direct evidence exists in the prevention of HF. A greater control of the other risk factors (eg, hypertension, hyperlipidemia) is, on the other hand, particularly important. Beta-blockers and ACE inhibitors have both been shown to have favorable effects across all spectrums of severity of HF. The ACE inhibitor ramipril has also been shown to prevent the development of HF in patients at risk without left ventricular dysfunction. The role of antiplatelet agents, warfarin, and statins is clear in the prevention of the coronary artery disease. However, it has not been adequately assessed in patients with HF and awaits the results of ongoing trials.

Pharmacologic therapy for patients with chronic heart failure and reduced systolic function: review of trials and practical considerations

Heart failure (HF) is a complex clinical syndrome resulting from any structural or functional cardiac disorder impairing the ability of the ventricles to fill with or eject blood. The approach to pharmacologic treatment has become a combined preventive and symptomatic management strategy. Ideally, treatment should be initiated in patients at risk, preventing disease progression. In patients who have progressed to symptomatic left ventricular dysfunction, certain therapies have been demonstrated to improve survival, decrease hospitalizations, and reduce symptoms. The mainstay therapies are angiotensin-converting enzyme (ACE) inhibitors and beta-blockers (bisoprolol, carvedilol, and metoprolol XL/CR), with diuretics to control fluid balance. In patients who cannot tolerate ACE inhibitors because of angioedema or severe cough, valsartan can be substituted. Valsartan should not be added in patients already taking an ACE inhibitor and a beta-blocker. Spironolactone is recommended in patients who have New York Heart Association (NYHA) class III to IV symptoms despite maximal therapies with ACE inhibitors, beta-blockers, diuretics, and digoxin. Low-dose digoxin, yielding a serum concentration <1 ng/mL can be added to improve symptoms and, possibly, mortality. The combination of hydralazine and isosorbide dinitrate might be useful in patients (especially in African Americans) who cannot tolerate ACE inhibitors or valsartan because of hypotension or renal dysfunction. Calcium antagonists, with the exception of amlodipine, oral or intravenous inotropes, and vasodilators, should be avoided in HF with reduced systolic function. Amiodarone should be used only if patients have a history of sudden death, or a history of ventricular fibrillation or sustained ventricular tachycardia, and should be used in conjunction with an implantable defibrillator [corrected]. Finally, anticoagulation is recommended only in patients who have concomitant atrial fibrillation or a previous history of cerebral or systemic emboli.

Prevention and management of chronic heart failure in management of asymptomatic patients

Symptomatic heart failure is preceded by a somewhat prolonged asymptomatic stage in many patients. The number of patients with asymptomatic heart dysfunction is about 4-fold greater than the number of patients with clinically overt heart failure. Pharmacologic treatment with angiotensin-converting enzyme inhibitors and beta-blockers (in particular carvedilol) of asymptomatic patients with systolic left ventricular (LV) dysfunction can prevent or delay the occurrence of symptoms and reduce mortality in the long term. Thus, it would be of utmost importance to recognize and appropriately treat these patients before they develop heart failure symptoms. The cost-effectiveness of screening for asymptomatic heart dysfunction in the general population and in cohorts at risk has not been extensively evaluated. A normal electrocardiogram has a high negative predictive value in patients at risk. Echocardiography is the best tool for diagnosis and characterization of heart dysfunction, but extensive use is limited by availability and cost. Natriuretic peptides (brain natriuretic peptide and N-terminal pro-brain natriuretic peptide) are very sensitive markers of heart dysfunction and volume overload, and their measurement has been proposed as a first-line test to select patients who need echocardiography. The definition of the etiology of LV dysfunction--in particular, of the ischemic etiology--has prognostic and therapeutic implications. In addition to revascularization, pharmacologic treatment with antiplatelets and statins is helpful in preventing new ischemic events and the development of heart failure. The prevention, or at least the delay, of clinical manifestations of heart failure is strongly related to an effective approach to the asymptomatic stage. Therefore, it is important to educate the entire medical community, particularly physicians in the primary care setting, about recognition and treatment of these patients.

Influence of perindopril on left ventricular global performance during the early phase of inferior acute myocardial infarction: assessment by Tei index

The beneficial effect of angiotensin-converting enzyme inhibitors (ACE inhibitors) on left ventricular (LV) function in patients with acute myocardial infarction (AMI) is widely known. However, controversy exists about their efficacy on patients with small infarcts and preserved LV systolic function. The aim of the present study was to detect the influence of the ACE-I perindopril on the global LV performance in patients with pure inferior AMI (AMI-I) using a Doppler-derived index (DI) that combines systolic and diastolic time intervals (Tei index). Our study included 40 patients with first AMI-I, mean age 60 years +/- 9.06 years (SD) and 24 age- and gender-matched normal patients who constituted the control group (COG). Patients were randomized into two groups to receive the conventional treatment of AMI-I (GCT) or the above therapy plus P (GP). Complete Doppler echocardiography (systolic and diastolic parameters), DI, and systolic blood pressure (SBP) were measured on the 8.07 +/- 1.16(SD) post-infarct day. The same examination was performed to COG. The DI was significantly lower in healthy patients(0.45 +/- 0.23)compared with the value in patients of either GP(0.56 +/- 0.03; P = 0.023)or GCT(0.78 +/- 0.05; P = 0.000). Moreover DI was higher in patients of GCT compared with that of GP(P = 0.000). In addition, perindopril administration decreased isovolumic relaxation time(IRT; 120.00 +/- 4.23 vs. 139.00 +/- 6.74; P = 0.006)and increased significantly ejection time (ET;274.25 +/- 7.35 vs. 253.50 +/- 7.68; P = 0.042). SBP in patients of GP was similar to that of GCT(120.5 +/- 2.85 mmHg vs. 112.5 +/- 3.49 mmHg; P = NS).

CONCLUSIONS

Global LV function (DI) is impaired in patients with AMI-I. Administration of perindopril has a favorable impact on LV performance in patients with AMI-I, achieved through improvement of the diastolic function (IRT), which indirectly improves LV systolic function (ET, DI). This beneficial influence of perindopril is the result of the direct tissue effect of the drug and not its hemodynamic action.

Cardiovascular risk factors, monitoring, and therapy for HIV-infected patients

Cardiovascular complications are important contributors to morbidity and mortality in HIV-infected patients. These complications can usually be detected at subclinical levels with monitoring, which can help guide targeted interventions. This article reviews available data on types and frequency of cardiovascular manifestations in HIV-infected patients and proposes monitoring strategies aimed at early subclinical detection. In particular, we recommend routine echocardiography for HIV-infected patients, even those with no evidence of cardiovascular disease. We also review preventive and therapeutic cardiovascular interventions. For procedures that have not been studied in HIV-infected patients, we extrapolate from evidence-based guidelines for the general population.

ACE inhibitors and ARBs in chronic heart failure: the established, the expected, and the pragmatic

ACE inhibitors have been shown to reduce mortality, reduce hospitalization, reduce symptoms, and increase exercise capacity in patients with heart failure and a large heart (low ejection fraction). The evidence is overwhelming. There are some subgroups of patients, such as the very elderly and those with a normal ejection fraction, where uncertainty still exists. The combination of a diuretic and an ACE inhibitor is currently the proper treatment of congestive heart failure; a beta-blocker should be added in selected patients. The evidence for the efficacy of ARB is less persuasive and, for the present, this class of drug should be prescribed only when an ACE inhibitor cannot be tolerated. The results of the trials emphasize an emerging problem in medicine, namely how to evaluate a new treatment that may be as efficacious as current therapy but with fewer side-effects. Proving equivalence in efficacy will be difficult, requiring large studies comparing new drugs with the best current treatment. The most common etiology of heart failure is coronary heart disease. If further studies provide more support for the idea that ACE inhibitors prevent ischemic episodes and delay the onset of heart failure, then a new indication for ACE inhibitors will be the prevention of heart failure.

Antiplatelet effects of angiotensin-converting enzyme inhibitors compared with aspirin and clopidogrel: a pilot study with whole-blood aggregometry

BACKGROUND

Although specific antiplatelet drugs are well-established and effective in atherosclerosis prevention, recent clinical trials have also shown that use of angiotensin-converting enzyme (ACE) inhibitors results in a decrease in cardiovascular events. Therefore, in this study, we sought to assess the coagulative activity of patients with cardiovascular disease grouped for treatment with either ACE inhibitors, aspirin, clopidogrel/aspirin, or none of these medications.

METHODS

Blood samples from 303 patients with cardiovascular disease were analyzed with whole-blood aggregometry. Platelet aggregation was determined by the increase in impedance across paired electrodes in response to the aggregatory agents adenosine diphosphate (ADP) or collagen.

RESULTS

As the central finding, platelet aggregation was attenuated by ACE inhibitors and by aspirin or clopidogrel/aspirin, which was indicated by a lower impedance increase compared with no medication. With ACE inhibition, platelet aggregation decreased by 33% (P =.042) after ADP induction. No significant antithrombotic effect was seen with aspirin alone (17%, P = 1.0), whereas a decrease in ADP-induced platelet aggregation was extensive with clopidogrel/aspirin (85%, P =.001). After collagen induction, platelet aggregation was reduced by 16% (P =.028) in the presence of ACE inhibitor therapy, whereas inhibition with aspirin and clopidogrel/aspirin was 23% (P =.004) and 35% (P =.026), respectively, compared with participants who were not treated.

CONCLUSIONS

These ex vivo data on whole-blood aggregometry provide direct evidence that ACE inhibitors decrease platelet aggregation, whereas aspirin and clopidogrel are confirmed as established antithrombotics. Pleiotropic effects of ACE inhibition on platelet function may contribute to the clinical benefit observed with this drug class on major cardiovascular end points.

[Analysis of differences in flow-mediated dilation in relation to the treatment of coronary patients]

INTRODUCTION

Flow-mediated dilation (FMD) is thought to be related to the development of coronary disease. We were interested in knowing the degree of FMD in a large sample of coronary patients in relation to the therapy they were given in clinical practice.

PATIENTS AND METHOD

We studied 1,081 coronary patients (age 68 +/- 12 years, 73% male) in which FMD was evaluated in the brachial artery. The patients were classified into 5 treatment groups (416 who receive 2 or more treatments were excluded): group A: 81 controls treated with aspirin, group B: 198 treated with ACE inhibitors, group C: 106 with calcium antagonists, group D: 145 with beta-blockers, and group E: 135 with lipid lowering medication (93% statins).

RESULTS

ANOVA was used to analyze the differences between groups. With regard to the number of risk factors present in each group, the patients treated with ACE inhibitors (2.44 +/- 0.79 vs 2.14 +/- 0.89; p < 0.05) and statins (3.45 +/- 0.70 vs 2.14 +/- 0.89; p < 0.05) had more risk factors than GrA and higher levels of LDL-cholesterol (ACE inhibitors 145.0 +/- 33.5 vs 128.5 +/- 32.2 and statins 157.8 +/- 45.3 vs 128.5 +/- 32.2; p < 0.05). GrB had a higher glycemia than controls (123.4 +/- 32.2 vs 114.7 +/- 33.7; p < 0.05). The control group was younger than the therapeutic groups (p < 0.05). Compared with the control group, FMD was significantly higher only in the group treated with ACE inhibitors (3.42 +/- 6.01 vs 0.82 +/- 6.04; p < 0.05). Multivariate logistical regression showed that treatment with ACE inhibitors and statins (p < 0.05) were independent predictors of FMD > 4%.

CONCLUSION

Treatment with ACE inhibitors or statins was predictive of the normalization of FMD in coronary patients in clinical practice.

Angiotensin II receptor blockers in heart failure

Heart failure remains a significant cause of morbidity and mortality, despite major advances in therapy. Angiotensin II, the principal mediator of the renin-angiotensin system, exerts both short-term (e.g., hemodynamic, renal) and long-term (e.g., inflammation, cardiac remodeling) effects in the pathophysiology of cardiovascular disease. The effects of angiotensin II appear to be more completely inhibited by angiotensin II receptor blockers (ARBs), which act at the subtype 1 receptor level, than by angiotensin-converting enzyme (ACE) inhibitors because pathways other than that of ACE contribute to the generation of angiotensin II. Evidence demonstrates that ARBs, when added to conventional treatment for patients with heart failure, are associated with a reduction in morbidity and mortality as well as an improvement in quality of life. Clinical trials of ARB therapy indicate that these agents are generally well tolerated, both alone and in combination with other neurohormonal inhibitors. The current role of ARBs in heart failure is as an alternative for patients who cannot tolerate therapy with an ACE inhibitor. A number of ongoing clinical studies are likely to further define or expand the role of ARBs in the treatment of cardiovascular disease.

Ongoing trials involving angiotensin-converting enzyme inhibitors

Angiotensin-converting enzyme inhibitors (ACEIs) are an important class of drugs in cardiovascular disease. As their name suggests, they act by blocking angiotensin converting enzyme, thereby limiting the production of angiotensin II, the most active component of the renin-angiotensin- aldosterone system. This system plays an important role in maintenance of blood pressure and electrolyte and fluid balance. Therefore, by blocking this system, the ACEIs have wide ranging effects. Recent trials have reaffirmed their place in the management of hypertension, congestive cardiac failure, in the prevention of renal complications in diabetes and the prevention of strokes in 'at risk' patients. There are still many ongoing trials using the ACEIs. These trials are mainly aimed at comparing their efficacy with 'older' drugs (such as betablockers) and 'newer' drugs such as the angiotensin receptor blockers and calcium antagonists in different indications, such as heart failure and diabetic nephropathy. The impact of these drugs on the prevention of macro- and micro vascular complications in diabetes is also being investigated. The results of all these trials, when available, are expected to reaffirm the important role of this class of drugs in our modern day medical armamentarium. In this review, the ongoing clinical trials involving ACEIs, the rationale behind these trials and what impact they hope to have on our current understanding of the role of this important class of drug in medical practice, will be discussed.

Abdominal aortic calcific deposits are associated with increased risk for congestive heart failure: the Framingham Heart Study

OBJECTIVES

We sought to determine the association of aortic atherosclerosis, detected by calcific deposits in the abdominal aorta seen on lateral lumbar radiographs, with risk for congestive heart failure (CHF).

BACKGROUND

Although the association between atherosclerotic coronary heart disease (CHD) and CHF has been extensively studied, there are limited prospective data regarding the association of extracoronary atherosclerosis with CHF.

METHODS

Lateral lumbar radiographs were obtained in 2467 Framingham Heart Study participants (1030 males and 1437 females) free of CHF in 1968. An abdominal aortic calcium (AAC) score was calculated for each subject based on the extent of calcium in the abdominal aorta. Proportional hazards models were used to test for associations between AAC score and CHF risk.

RESULTS

There were 141 cases of CHF in men and 169 cases in women. In men, the multivariable-adjusted risk for CHF was increased for the second (hazards ratio [HR] 1.5, 95% CI 0.9-2.5) and third (HR 2.2, 95% CI 1.3-3.7) tertiles compared with the lowest tertile. Similarly, in women, the multivariable-adjusted risk for CHF was increased for the second (HR 1.8, 95% CI 1.1-2.9) and third (HR 3.2, 95% CI 2.0-5.1) tertiles compared with the lowest tertile. After further adjustment for CHD occurring prior to the onset of CHF, risk remained significantly increased for both men and women.

CONCLUSIONS

Atherosclerosis of the abdominal aorta is an important risk factor for CHF, independent of CHD and other risk factors. Noninvasive detection and quantification of atherosclerosis may be useful in identifying high-risk individuals likely to benefit from strategies aimed at preventing CHF. The possibility of a link between AAC and vascular compliance deserves further study.

Gene polymorphism and coronary risk factors in Indian population

Asian Indians who have settled overseas and those in urban India have increased risk of coronary events. Reasons for this increased risk are thought to be genetic but are yet unclear. Advances in molecular cardiology have revealed a number of single nucleotide polymorphisms associated with atherosclerosis. In this review, gene polymorphisms that have been associated with coronary diseases among Indians are discussed. Topics include the genes involved in hyperlipidemia, hypertension, and homocysteine. Mutations in the low-density lipoprotein receptor (LDLR) gene resulting in familial hypercholesterolemia have strong association with premature atherosclerosis. Common polymorphism of the apolipoproteins (apo) B-100 and E genes have been associated with variation in lipid and lipoprotein levels. Recently identified polymorphisms in the apoC3 (T-455C, C-482T), and cholesteryl ester transfer protein (CETP) (B1/B2 allele) genes are associated with increased triglycerides and reduced high-density lipoprotein (HDL)-levels, a feature now also common among Asian Indians. Angiotensin-converting enzyme-deletion (DD) polymorphism has been shown to influence beta-blocker therapy in heart failure. Mutations in methylenetetrahydrofolate reductase (C667T), cystathionine beta-synthase (T833C), and methionine synthase (A2756G) genes cause hyperhomocysteinemia, an independent risk factor for atherothrombosis. As the genetics of atherosclerosis continues to evolve, these factors along with the newer emerging factors may become a part of the routine assessment, aiding prediction of future coronary events.

Prevention of heart failure

BACKGROUND

The number of people in the United States with heart failure (HF) is expected to rise dramatically as the population ages unless efforts to prevent HF improve.

METHODS AND RESULTS

PubMed/MEDLINE searches were conducted to identify treatment trials of hypertension, hypercholesterolemia, asymptomatic left ventricular systolic dysfunction, and diabetes that reported HF incidence. Treatment of hypertension reduces the incidence of HF by approximately 50%, even among very elderly patients. Diuretics, beta-blockers, and angiotensin-converting enzyme (ACE) inhibitors appear more effective than calcium channel blockers and doxazosin. Hydroxy methylglutaryl coenzyme A (HMG CoA) reductase inhibitors reduce the incidence of HF by approximately 20% among patients with hypercholesterolemia and coronary artery disease. ACE inhibitors reduce HF incidence by 37% among patients with reduced systolic function and by 23% among patients with coronary artery disease and normal systolic function. Observational studies have shown lower HF incidence among people with diabetes with better glycemic control. Unfortunately, all of these effective therapies appear to be underused, and control of hypertension is particularly poor.

CONCLUSIONS

If clinical practice can live up to the potential shown from clinical trials, the suffering and economic toll imposed by HF can be dramatically reduced. Improved control of hypertension, primary prevention of myocardial infarction, and more widespread use of secondary prevention measures are essential.

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in atherosclerosis

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) effectively interfere with the renin-angiotensin system and exert various beneficial actions on cardiac and vascular structure and function, beyond their blood pressure-lowering effects. Randomized, controlled clinical trials have shown that ACE inhibitors improve endothelial function, cardiac and vascular remodeling, retard the anatomic progression of atherosclerosis, and reduce the risk of myocardial infarction, stroke, and cardiovascular death. Therefore, these agents are recommended in the treatment of a wide range of patients at risk for adverse cardiovascular outcomes, including those with coronary disease, prior stroke, peripheral arterial disease, high-risk diabetes, hypertension, and heart failure. ARBs are effective blood pressure- lowering and renoprotective agents and can be used in heart failure in patients who do not tolerate ACE inhibitors. The role of ARBs in the prevention of atherosclerosis and its sequelae is currently under investigation. The use of combined ACE inhibitor plus ARB therapy offers theoretical advantages over the use of each of these agents alone and is also under investigation in large, randomized clinical trials.

Ramipril: a review of its use in the prevention of cardiovascular outcomes

Ramipril, an angiotensin-converting enzyme (ACE) inhibitor, is a prodrug which is rapidly hydrolysed after absorption to the active metabolite ramiprilat. Earlier trials have shown that ACE inhibitors, when given to patients with low ejection fractions, have reduced the relative risk of myocardial infarction (MI) and other ischaemic events by 14 to 23%. Subsequently, the double-blind, randomised, placebo-controlled, multicentre Heart Outcomes Prevention Evaluation (HOPE) study has shown that, in patients who are not known to have low ejection fraction or heart failure but are at increased risk for developing cardiovascular events, ramipril reduced the incidence of stroke, MI and death due to cardiovascular disease. Results from the HOPE study, in which 9297 patients were randomised to receive either ramipril 10 mg/day or placebo for a mean of 4.5 years, indicate that ramipril reduced the relative risk of the composite outcome of MI, stroke and cardiovascular death by 22%. The incidence of the composite outcome was significantly lower in the ramipril group than in the placebo group (14.0 vs 17.8%). Patients who received ramipril, compared with placebo recipients, had a significantly decreased incidence of stroke, MI or death due to cardiovascular disease (3.4 vs 4.9%, 9.9 vs 12.3% and 6.1 vs 8.1%, respectively). The relative risk of death from any cause was reduced among patients who received ramipril. In addition, treatment with ramipril reduced as the incidence of revascularisation procedures, and, among patients with diabetes mellitus, ramipril reduced the incidence of complications related to diabetes mellitus, including the development of overt nephropathy. Moreover, in patients without a previous diagnosis of diabetes mellitus, ramipril, compared with placebo, significantly reduced the development of diabetes mellitus. Furthermore, compared with patients receiving placebo, patients receiving ramipril had a reduced rate of progression of carotid artery wall thickness.

CONCLUSION

Ramipril 10 mg/day can significantly reduce the incidence of MI, stroke or death from cardiovascular causes in patients aged > or =55 years who are at increased risk for the development of ischaemic cardiovascular events due to a history of stroke, coronary artery disease (with controlled blood pressure), diabetes mellitus plus at least one other risk factor or peripheral vascular disease but no heart failure or low ejection fraction. Therefore, in addition to dietary and lifestyle modifications, ramipril should be an integral part of secondary prevention therapy in patients at increased risk for the development of cardiovascular events.

Vascular inflammation and the renin-angiotensin system

It is now well established that vascular inflammation is an independent risk factor for the development of atherosclerosis. In otherwise healthy patients, chronic elevations of circulating interleukin-6 or its biomarkers are predictors for increased risk in the development and progression of ischemic heart disease. Although multifactorial in etiology, vascular inflammation produces atherosclerosis by the continuous recruitment of circulating monocytes into the vessel wall and by contributing to an oxidant-rich inflammatory milieu that induces phenotypic changes in resident (noninflammatory) cells. In addition, the renin-angiotensin system (RAS) has important modulatory activities in the atherogenic process. Recent work has shown that angiotensin II (Ang II) has significant proinflammatory actions in the vascular wall, inducing the production of reactive oxygen species, inflammatory cytokines, and adhesion molecules. These latter effects on gene expression are mediated, at least in part, through the cytoplasmic nuclear factor-kappaB transcription factor. Through these actions, Ang II augments vascular inflammation, induces endothelial dysfunction, and, in so doing, enhances the atherogenic process. Our recent studies have defined a molecular mechanism for a biological positive-feedback loop that explains how vascular inflammation can be self-sustaining through upregulation of the vessel wall Ang II tone. Ang II produced locally by the inflamed vessel induces the synthesis and secretion of interleukin-6, a cytokine that induces synthesis of angiotensinogen in the liver through a janus kinase (JAK)/signal transducer and activator of transcription (STAT)-3 pathway. Enhanced angiotensinogen production, in turn, supplies more substrate to the activated vascular RAS, where locally produced Ang II synergizes with oxidized lipid to perpetuate atherosclerotic vascular inflammation. These observations suggest that one mechanism by which RAS antagonists prevent atherosclerosis is by reducing vascular inflammation. Moreover, antagonizing the vascular nuclear factor-kappaB and/or hepatic JAK/STAT pathways may modulate the atherosclerotic process.

Comparison of coronary artery bypass grafting versus medical therapy on long-term outcome in patients with ischemic cardiomyopathy (a 25-year experience from the Duke Cardiovascular Disease Databank)

In this observational treatment comparison in a single center over 25 years, we sought to assess long-term outcomes of coronary artery bypass surgery (CABG) or medical therapy in patients with heart failure, coronary artery disease, and left ventricular systolic dysfunction. The benefit of CABG compared with medical therapy alone in these patients is a source of continuing clinical debate. This analysis considered all patients with New York Heart Association class II or greater symptoms, 1 or more epicardial coronary vessels with a > or = 75% stenosis, and a left ventricular ejection fraction <40% who underwent an initial cardiac catheterization at Duke University Medical Center from 1969 to 1994. Patients were classified into the medical therapy group (n = 1,052) or CABG group (n = 339) depending on which therapy they received within 30 days of catheterization. Cardiovascular event and mortality follow-up commenced on the day of CABG, or at catheterization plus 8 days (the mean time to CABG) for the medical therapy arm. A Cox proportional-hazards model was employed to adjust for differences in baseline characteristics. In the first 30 days from baseline, there was an interaction between treatment strategy and number of diseased vessels. Unadjusted, event-free, and adjusted survival strongly favored CABG over medical therapy after 30 days to >10 years regardless of the extent of coronary disease (p <0.001). Thus, regardless of the severity of coronary disease, heart failure symptoms, or ventricular dysfunction, CABG provides extended event-free and survival advantage over medical therapy alone in patients with an ischemic cardiomyopathy.

Dissecting the role of chymase in angiotensin II formation and heart and blood vessel diseases

Inhibition of angiotensin II action or its formation by angiotensin-converting enzyme has been highly successful in the treatment of cardiovascular diseases. Since the identification of chymase as a major angiotensin II-forming enzyme in the human heart and its vessels more than a decade ago, numerous studies have sought to understand the importance of this enzyme in tissue angiotensin II formation and in the pathogenesis of hypertension, congestive heart failure, and vascular disease. Recent studies show that chymase and angiotensin-converting enzyme regulate angiotensin II production in distinct tissue compartments and that, in the pathogenesis of cardiovascular diseases, chymase-dependent effects extend beyond its ability to regulate tissue angiotensin II levels.

Cholesterol-induced upregulation of angiotensin II and its effects on monocyte-endothelial interaction and superoxide production

Atherogenesis involves an early endothelial dysfunction hallmarked by elevated free radical production and increased adhesiveness for monocytes. It was hypothesized that activation of the tissue renin angiotensin system may contribute to the endothelial alteration. To test this hypothesis, thoracic aortae were isolated from normocholesterolemic (NC; n = 6) and hypercholesterolemic (HC; n = 6; diet: 0.5% cholesterol; 6 weeks) New Zealand white rabbits, and incubated for 2 h with the angiotensin II (Ang II) receptor antagonist Sar-1,Ile-8-Ang II, the antioxidant pyrolidine dithiocarbamate (PDTC) and the protein kinase C (PKC) antagonist staurosporin. Superoxide production from aortic segments was measured by lucigenin-enhanced chemiluminescence. In comparison to the normocholesterolemic state, hypercholesterolemia led to a significant increase in superoxide production (221 +/- 44%, p < 0.02); this was reduced by ex vivo treatment of the vessel segment with Ang II-antagonist (to 130 +/- 29%; p < 0.04 vs HC), or PKC-antagonist (to 86 +/- 26%; p < 0.001 vs HC), or PDTC (to 103 +/- 27%; p < 0.02 vs HC). Monocyte-endothelial interaction was assessed by functional binding assay. When compared to normocholesterolemic rabbits, hypercholesterolemia led to a twofold increase in monocyte binding (74 +/- 13 vs 37 +/- 4 monocytoid cells per high power field (m/hpf); p < 0.03). The Ang II-antagonist and the PKC-antagonist led to a normalization of monocyte-endothelial binding (Ang II-antagonist: 37 +/- 9 m/hpf; PKC-antagonist: 41 +/- 17 m/hpf; p < 0.05). In conclusion, these results indicate that hypercholesterolemia activates the tissue renin angiotensin system, which results in an increased endothelial production of superoxide and monocyte adhesiveness. Ang II-antagonist inhibits free radical production and monocyte adhesion through a mechanism which may include PKC.

Angiotensin-converting enzyme inhibitors improve coronary flow reserve in dilated cardiomyopathy by a bradykinin-mediated, nitric oxide-dependent mechanism

BACKGROUND

ACE inhibitors have been used extensively in heart failure, where they induce systemic vasodilatation. ACE inhibitors have also been shown to reduce ischemic events after myocardial infarction, although their mechanisms of action on the coronary circulation are less well understood. The purpose of the present study was to determine the effects and the mechanism of action of the ACE inhibitor enalaprilat and the AT1 antagonist losartan on regional myocardial perfusion and coronary flow and vasodilator reserve in conscious dogs with pacing-induced dilated cardiomyopathy (DCM).

METHODS AND RESULTS

Twenty-seven conscious, chronically instrumented dogs were studied during advanced stages of dilated cardiomyopathy, which was induced by rapid pacing. Enalaprilat (1.25 mg IV) improved transmural distribution (endocardial/epicardial ratio) at rest (baseline, 0.91+/-0.11; enalaprilat, 1.02+/-0.07 mL/min per g; P<0.05) and during atrial pacing (baseline, 0.82+/-0.11; enalaprilat, 0.98+/-0.07; P<0.05). Enalaprilat also restored subendocardial coronary flow reserve (CFR) (baseline CFR, 1.89+/-0.11; enalaprilat CFR, 2.74+/-0.33; P<0.05) in DCM. These effects were abolished by pretreatment with the NO synthase inhibitor nitro-L-arginine. The effects were recapitulated by the bradykinin(2) receptor agonist cereport but not by the AT1 antagonist losartan.

CONCLUSIONS

The ACE inhibitor enalaprilat improves transmural myocardial perfusion at rest and after chronotropic stress and restores impaired subendocardial coronary flow and vasodilator reserve in DCM. The effects of enalaprilat were bradykinin mediated and NO dependent and were not recapitulated by losartan. These data suggest beneficial effects of ACE inhibitors on the coronary circulation in DCM that are not shared by AT1 receptor antagonists.

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.

Statins and chronic heart failure: do we need a large-scale outcome trial?

Hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) are of proven clinical benefit in coronary heart disease, at least in those patients who do not have overt chronic heart failure (CHF). However, as there have been no prospective clinical trials of statins in CHF patients, the question arises as to whether the benefits observed in the absence of CHF can be necessarily inferred in those patients in whom CHF is established. In this review, the evidence base stating support of the use of statins in CHF is presented, as well as theoretical considerations as to why these agents may not necessarily be of benefit in this setting. The beneficial potential of statins clearly relates to their plaque stabilization properties and associated improvements in endothelial function, which together should reduce the risk of further infarction and, perhaps, the ischemic burden on the failing ventricle. Furthermore, these agents may have beneficial effects independent of lipid lowering. These include actions on neoangiogenesis, downregulation of AT(1) receptors, inhibition of proinflammatory cytokine activity and favorable modulation of the autonomic nervous system. The potential adverse effects of statins in CHF include reduction in levels of coenzyme Q10 (which may further exacerbate oxidative stress in CHF) and loss of the protection that lipoproteins may provide through binding and detoxifying endotoxins entering the circulation via the gut. In support of these possibilities are epidemiologic data linking a lower serum cholesterol with a poorer prognosis in CHF. These uncertainties indicate the need for a definitive outcome trial to assess the efficacy and safety of statins in CHF, despite their current widespread, non-evidence based use in this population.

Angiotensin II as a cardiovascular risk factor

A renin-angiotensin level that is inappropriately high for the systemic blood pressure and the state of sodium balance is now recognized to be one of the modifiable cardiovascular risk factors. Angiotensin acts both as a circulating hormone and as a locally acting paracrine/autocrine/intracrine factor. The adverse effects of angiotensin on the heart include the mechanical results of elevated resistance to the pumping function of the myocardium, as well as the effects of neurohumoral abnormalities on various cardiac structures. In addition, cardiac damage follows acute ischaemic injury or chronic energy starvation due to coronary artery disease, attributable to either mechanical obstruction (atherosclerotic and/or thrombotic) or functional stenosis (vasospasm). Activation of the renin-angiotensin system has several haemodynamic and humoral consequences, all of which may damage the myocardium. These include acute myocardial ischaemia, left-ventricular hypertrophy, arrhythmias, alterations in the coagulation-fibrinolysis equilibrium, increased oxidative stress, and pro-inflammatory activity. A brief review of some of the mechanisms by which activation of the renin-angiotensin system can inflict damage on the heart is presented.

Pretreatment with angiotensin-converting enzyme inhibitors attenuates ischemia-reperfusion injury

BACKGROUND

The Heart Outcomes Prevention Evaluation (HOPE) trial demonstrated that ischemic events are decreased in patients receiving angiotensin-converting enzyme (ACE) inhibitors. This study sought to determine whether pretreatment with ACE inhibitors would attentuate ischemic injury during surgical revascularization of ischemic myocardium.

METHODS

In a porcine model, the second and third diagonal vessels were occluded for 90 minutes, followed by 45 minutes of cardioplegic arrest, and 180 minutes of reperfusion. Ten pigs received quinapril (20 mg p.o. q.d.) for 7 days prior to surgery; 10 others received no-ACE inhibitors.

RESULTS

Quinapril-treated animals required less cardioversions for ventricular arrhythmias (1.58 +/- 0.40 vs 2.77 +/- 0.22; p < 0.05), had higher wall motion scores assessed by two-dimensional echocardiography (4 = normal to -1 = dyskinesia; 2.11 +/- 0.10 vs 1.50 +/- 0.07; p < 0.05), more complete coronary artery endothelial relaxation to bradykinin (45% +/- 3% vs 7% +/- 4%; p < 0.005), and lower infarct size (24.0% +/- 3.0% vs 40.0% +/- 1.7%; p < 0.0001).

CONCLUSIONS

ACE inhibition prior to coronary revascularization enhances myocardial protection by decreasing ventricular irritability, improving regional wall motion, lowering infarct size, and preserving endothelial function.

Effects of eprosartan versus hydrochlorothiazide on markers of vascular oxidation and inflammation and blood pressure (renin-angiotensin system antagonists, oxidation, and inflammation)

Antagonists of the renin-angiotensin system, such as angiotensin type 1 (AT(1)) receptor inhibitors and angiotensin-converting enzyme inhibitors, are becoming increasingly popular agents in treating patients with systemic hypertension and minimizing organ damage. In the present study, we compared the effects of eprosartan, an AT(1) receptor inhibitor, with the diuretic hydrochlorothiazide in a group of newly diagnosed hypertensive patients with multiple risk factors for atherosclerosis. The subjects were monitored and tested at 0 and 4 weeks to determine their individual effects on vascular and inflammatory markers. Although blood pressure reduction was comparable between the 2 agents, there were notable differences in their effects on markers of inflammation and oxidation. We observed a 28% reduction in neutrophil superoxide anion generating capacity, a 34% reduction in soluble monocyte chemotactic protein-1, and a 35% reduction in soluble vascular cell adhesion molecule with eprosartan therapy (all p <0.05 from the start of therapy). In addition, eprosartan showed further benefit in its ability to increase low-density lipoprotein oxidation lag time, suggesting an increased resistance to oxidation and/or modification of low-density lipoprotein. Although hydrochlorothiazide was effective in blood pressure reduction, there were no significant changes in any of the above parameters after 4 weeks of treatment. These findings suggest that eprosartan, an AT(1) receptor inhibitor, effectively reduces systemic blood pressure and, compared with hydrochlorothiazide, suggests additional benefits in the vasculature by inhibiting mechanisms of inflammation and oxidation.

The renin-angiotensin system in mitral regurgitation: a typical example of tissue activation

Mitral regurgitation (MR) creates a unique hemodynamic stress by inducing a low pressure form of volume overload due to ejection into the left atrium, without the pressure component that accompanies aortic regurgitation. Chronic therapy with vasodilators has been shown to reduce left ventricular wall stress, and thereby delay or obviate the need for valve replacement in aortic regurgitation; however, no data are currently available in patients with chronic MR using standard vasodilators or agents that block renin-angiotensin system (RAS) components. Studies in a clinically relevant dog model of experimentally induced MR demonstrate upregulation of the cardiac RAS. However, RAS blockade fails to improve left ventricular remodeling and function, whereas beta-adrenergic blockade results in restoration of left ventricular chamber and myocyte function.

Perindopril alters vascular angiotensin-converting enzyme, AT(1) receptor, and nitric oxide synthase expression in patients with coronary heart disease

Angiotensin-converting enzyme inhibitors (ACEi) reduce cardiovascular morbidity and mortality by improving coronary perfusion, reducing ventricular hypertrophy and remodeling, and preventing progression of coronary atherosclerosis. However, the cellular mechanisms underlying the beneficial effects of ACEi are not fully understood. We studied the in vivo effects of ACE inhibition with perindopril on cellular expression of ACE, AT(1) receptors and 2 nitric oxide synthase (NOS) isoforms, endothelial (eNOS) and inducible NOS (iNOS), in human blood vessels using quantitative in vitro autoradiography and immunocytochemistry. Seven patients with ischemic heart disease were treated with perindopril (4 mg/d) for up to 5 weeks before elective coronary bypass surgery, whereas controls did not receive the ACEi (n=7). Perindopril decreased plasma ACE by 70% and the plasma angiotensin II to angiotensin I ratio by 57% and reduced vascular ACE to approximately 65% of control levels in both endothelium and adventitia. By contrast, AT(1) receptor binding in vascular smooth muscle cells was increased by 80% in patients treated with perindopril as confirmed by immunocytochemistry. eNOS was expressed primarily in endothelial cells, whereas little iNOS expression occurred in vascular smooth muscle cells of untreated patients. Both eNOS and iNOS expression seemed to increase during perindopril treatment. These results suggest that suppression of angiotensin II formation in the vascular wall and increased expression of eNOS and iNOS during ACE inhibition may be beneficial in reversing endothelial dysfunction in patients with cardiovascular disease. Because vascular AT(1) receptor expression is increased during chronic ACE inhibition, more clinical studies are required to determine whether it is necessary to combine ACE inhibitors and AT(1) receptor antagonists in clinical management of heart failure, coronary heart disease, and hypertension

Spironolactone abolishes the relationship between aldosterone and plasminogen activator inhibitor-1 in humans

Recent studies have defined a link between the renin-angiotensin-aldosterone system and fibrinolysis. The present study tests the hypothesis that endogenous aldosterone regulates plasminogen activator inhibitor-1 (PAI-1) production in humans. Hemodynamic parameters, PAI-1 and tissue-type plasminogen activator (t-PA) antigen, potassium, PRA, angiotensin II, and aldosterone were measured in nine male hypertensive subjects after a 3-wk washout, after 2 wk of hydrochlorothiazide (HCTZ; 25 mg plus 20 mmol KCl/d), and after 2 wk of spironolactone (100 mg/d plus KCl placebo). Spironolactone (P = 0.04), but not HCTZ (P = 0.57 vs. baseline; P = 0.1 vs. spironolactone), significantly lowered systolic blood pressure. Angiotensin II increased from baseline during both HCTZ (P = 0.02) and spironolactone (P = 0.02 vs. baseline; P = 0.19 vs. HCTZ) treatments. Although both HCTZ (P = 0.004) and spironolactone (P < 0.001 vs. baseline) increased aldosterone, the effect was greater with spironolactone (P < 0.001 vs. HCTZ). HCTZ increased PAI-1 antigen (P = 0.02), but did not alter t-PA antigen. In contrast, there was no effect of spironolactone on PAI-1 antigen (P = 0.28), whereas t-PA antigen was increased (P = 0.01). There was a significant correlation between PAI-1 antigen and serum aldosterone during both baseline and HCTZ study days (r(2) = 0.57; P = 0.0003); however, treatment with spironolactone abolished this correlation (r(2) = 0.13; P = 0.33). This study provides evidence that endogenous aldosterone influences PAI-1 production in humans.

Potential indications for angiotensin-converting enzyme inhibitors in atherosclerotic vascular disease

Angiotensin-converting enzyme (ACE) inhibitors are well established as first-line therapy for patients with left ventricular dysfunction, diabetic patients with hypertension or renal disease, and patients recovering from myocardial infarction. Angiotensin II and bradykinin regulate cellular proliferation, inflammation, and endothelial function, thus playing an important role in the pathogenesis of atherosclerosis. A large body of experimental evidence reporting that ACE inhibitors limit these effects has formed the rationale for major clinical trials of these drugs in the management of atherosclerotic vascular disease. The first trial to be completed demonstrated that ACE inhibition improves the prognosis of patients who have, or are at risk of, atherosclerotic vascular disease, independent of its effects on left ventricular function and hypertension. Expanding the indications for ACE inhibitors is now evidence driven, although the choice of agent for these new indications remains to be determined by further research.

Acute ischemic syndromes. Adjunctive therapy

The acute coronary syndromes (ACS) represent a heterogeneous group of patients along a continuum of risk from unstable angina to non-ST-segment elevation myocardial infarction. ACS is a term that has been used to describe the constellation of clinical symptoms that represent acute myocardial ischemia. This article reviews the adjunctive medications that are used during emergency cardiovasculare care for the early management of patients experiencing the ACS. The adjunctive therapies are divided into early immediate treatment and then subsequent management in the acute care setting.

Vasopeptidase inhibition: effective blood pressure control for vascular protection

Angiotensin converting enzyme (ACE) inhibition is a well-established principle in the treatment of hypertension, and numerous large scale clinical studies have clearly demonstrated the beneficial effects of inhibiting the renin-angiotensin-aldosterone system (RAS) in hypertension. The clinical success of ACE inhibitors encouraged attempts to inhibit other key enzymes in the regulation of vascular tone, such as the neutral endopeptidase (NEP). Similar to ACE, NEP is an endothelial cell surface metalloproteinase, which is involved in the degradation of several regulatory peptides including the natriuretic peptides, and augments vasodilatation and natriuresis through increased levels of atrial natriuretic peptide. By inhibiting the RAS and potentiating the natriuretic peptide system at the same time, combined NEP/ACE inhibitors, the so-called "vasopeptidase inhibitors," reduce vasoconstriction and enhance vasodilatation, and in turn decrease peripheral vascular resistance and blood pressure. Within the vessel wall this may lead to a reduction of vasoconstrictor and proliferative mediators such as angiotensin II and endothelin-1, and may increase local levels of bradykinin as well as natriuretic peptides. Based on these considerations, numerous preclinical studies with vasopeptidase inhibitors have been performed and reveal promising results in experimental hypertension. Correspondingly, large-scale clinical studies in patients with hypertension are on the way, to transfer the principle of vasopeptidase inhibition from bench to bedside.

Congestive heart failure: what should be the initial therapy and why?

Left ventricular systolic dysfunction is associated with neurohormonal activation which contributes to progressive ventricular remodeling and worsening clinical heart failure. Renin-angiotensin-aldosterone and sympathetic nervous systems are activated, not only in patients with clinically overt heart failure, but also in patients with asymptomatic or minimally symptomatic left ventricular systolic dysfunction. Activation of the angiotensin and adrenergic systems produces deleterious effects on systemic and coronary hemodynamics, promotes myocyte hypertrophy and fibroblast growth, and myocyte necrosis and apoptosis. Thus, therapy of heart failure should consist of pharmacologic agents not only to relieve symptoms but also to prevent and attenuate ventricular remodeling and progressive heart failure, thereby improving prognosis. In patients who are symptomatic, ACE inhibitors along with digitalis and diuretics as initial therapy (triple therapy) have the greater potential to improve exercise tolerance and decrease the incidence of treatment failure compared with diuretics alone or a combination of diuretics and digitalis. Diuretics alone should not be considered for long-term therapy as plasma renin activity, angiotensin II, aldosterone, norepinephrine and vasopressin levels may increase. ACE inhibitors decrease mortality in patients with heart failure resulting from left ventricular systolic dysfunction. The results of presently available studies indicate that angiotensin II receptor blockers (ARBs) do not provide any advantage over ACE inhibitors regarding survival benefit but may be better tolerated. Long-term adrenergic inhibition with the use of ss-adrenoceptor antagonists added to ACE inhibitors is associated with attenuation of ventricular remodeling, improvement in ventricular function and clinical class and survival of patients with symptomatic systolic left ventricular failure. Thus, initial pharmacotherapy for systolic heart failure should consist of: maximal tolerated dosages of ACE inhibitors;ARBs if ACE inhibitors are not tolerated because of intractable cough or angioedema;adequate dosages of hydralazine and isosorbide dinitrate if ACE inhibitors or ARBs are not tolerated; relatively low dosages of digoxin (serum concentrations of < or = 1.0 ng/dl) if not contraindicated; and diuretics to relieve congestive symptoms. Addition of spironolactone to ACE inhibitors can result in a significant reduction in the risk of sudden death in patients with symptomatic severe heart failure. Myocardial infarction resulting from ischemic heart disease is the most common cause of systolic left ventricular failure and the therapeutic modalities with potential to reduce the risks of myocardial infraction, such as risk factor modification, adequate control of diabetes and hypertension, antiplatelet agents and lipid-lowering agents, should also be included in the initial therapy.

Is aspirin "the weakest link" in cardiovascular prophylaxis? The surprising lack of evidence supporting the use of aspirin for cardiovascular disease

It is currently fashionable to prescribe aspirin, long-term to people with or at high risk of vascular events due to atherosclerosis. There is a moderately conclusive evidence for a short-term benefit after an acute vascular event. However, there is remarkably little evidence that long-term aspirin is effective for the prevention of vascular events and managing side effects may be expensive. Reductions in nonfatal vascular events may reflect an ability of aspirin to alter cosmetically the presentation of disease without exerting real benefit. Cardiovascular medicine appears prone to fads and fashions that are poorly substantiated by evidence. The current fashion for prescribing aspirin is reminiscent of the now discredited practice of widespread prescription of class I anti-arrhythmic drugs for ventricular ectopics. We should learn from experience.

The relevance of tissue angiotensin-converting enzyme: manifestations in mechanistic and endpoint data

Angiotensin-converting enzyme (ACE) is primarily localized (>90%) in various tissues and organs, most notably on the endothelium but also within parenchyma and inflammatory cells. Tissue ACE is now recognized as a key factor in cardiovascular and renal diseases. Endothelial dysfunction, in response to a number of risk factors or injury such as hypertension, diabetes mellitus, hypercholesteremia, and cigarette smoking, disrupts the balance of vasodilation and vasoconstriction, vascular smooth muscle cell growth, the inflammatory and oxidative state of the vessel wall, and is associated with activation of tissue ACE. Pathologic activation of local ACE can have deleterious effects on the heart, vasculature, and the kidneys. The imbalance resulting from increased local formation of angiotensin II and increased bradykinin degradation favors cardiovascular disease. Indeed, ACE inhibitors effectively reduce high blood pressure and exert cardio- and renoprotective actions. Recent evidence suggests that a principal target of ACE inhibitor action is at the tissue sites. Pharmacokinetic properties of various ACE inhibitors indicate that there are differences in their binding characteristics for tissue ACE. Clinical studies comparing the effects of antihypertensives (especially ACE inhibitors) on endothelial function suggest differences. More comparative experimental and clinical studies should address the significance of these drug differences and their impact on clinical events.

Cardiovascular monitoring and therapy for HIV-infected patients

Cardiovascular complications are important contributors to morbidity and mortality in HIV-infected patients. These complications can usually be detected at subclinical levels with monitoring, which can help guide targeted interventions. This article reviews available data on types and frequency of cardiovascular manifestations in HIV+ patients and proposes monitoring strategies aimed at early subclinical detection. In particular, we recommend routine echocardiography for HIV+ patients, even those with no evidence of cardiovascular disease. We also review preventive and therapeutic cardiovascular interventions. For procedures that have not been studied in HIV+ patients, we extrapolate from evidence-based guidelines for the general population.

Physiological and pathophysiological functions of the AT(2) subtype receptor of angiotensin II: from large arteries to the microcirculation

Angiotensin II exerts a potent role in the control of hemodynamic and renal homeostasis. Angiotensin II is also a local and biologically active mediator involved in both endothelial and smooth muscle cell function acting on 2 receptor subtypes: type 1 (AT(1)R) and type 2 (AT(2)R). Whereas the key role of AT(2)R in the development of the embryo has been extensively studied, the role of AT(2)R in the adult remains more questionable, especially in humans. In vitro studies in cultured cells and in isolated segments of aorta have shown that AT(2)R stimulation could lead to the production of vasoactive substances, among which NO is certainly the most cited, suggesting that acute AT(2)R stimulation will produce vasodilation. However, in different organs or in small arteries isolated from different type of tissues, other vasoactive substances may also mediate AT(2)R-dependent dilation. Sometimes, such as in large renal arteries, AT(2)R stimulation may lead to vasoconstriction, although it is not always seen. In isolated arteries submitted to physiological conditions of pressure and flow, AT(2)R stimulation may also have a role in shear stress-induced dilation through a endothelial production of NO. Thus, when acutely stimulated, the most probable response expected from AT(2)R stimulation will be a vasodilation. Therefore, in the perspective of a chronic AT(1)R blockade in patients, overstimulation of AT(2)R might be beneficial, given their potential vasodilator effect. Concerning the possible role of AT(2)R in cardiovascular remodeling, the situation is more controversial. In vitro AT(2)R stimulation clearly inhibits cardiac and vascular smooth muscle growth and proliferation, stimulates apoptosis, and promotes extra cellular matrix synthesis. In vivo, the situation might be less beneficial if not deleterious; indeed, if chronic AT(2)R overstimulation would lead to cardiovascular hypertrophy and fibrosis, then the long-term consequences of chronic AT(1)R blockade, and thus AT(2)R overstimulation, require more in-depth analysis.

Contemporary management of chronic stable angina

Chronic stable angina is a common condition with a prognosis that is less benign than is generally appreciated. The optimal treatment strategy of this disorder is unclear, and few anti-ischaemic agents have been rigorously tested in prospectively randomised mortality studies. The evidence base for the anti-ischaemic therapy of chronic angina draws upon data 'borrowed' from studies in acute coronary syndromes, and from studies in chronic angina using surrogate endpoints such as ambulatory silent ischaemia. Such evidence leads us to believe that anti-ischaemic therapy with beta-blockers offers a mortality benefit in chronic angina. In contrast, the mortality benefit of lipid lowering therapy and antiplatelet agents is well proven. Angioplasty offers no mortality benefit in the treatment of chronic angina, although it is more effective than medical therapy alone for the relief of symptoms. In a few patients with high order proximal coronary disease, coronary bypass surgery offers a distinct mortality advantage compared with medical treatment alone. Most patients, however, do not warrant such an approach, and only require surgery for when they remain symptomatic despite adequate medical therapy. Alternative strategies such as cardiac transplantation, transmyocardial laser revascularisation and spinal cord stimulation are now accepted in a subgroup of patients for the treatment of chronic angina refractory to standard therapy.