Role of RAAS Inhibition in the Prevention of Cardiovascular Disease

The pathogenesis of cardiovascular disease is a complex and dynamic process. The renin-angiotensin-aldosterone system (RAAS) is a potent and powerful mediator in the homeostasis of the cardiovascular and renal systems. RAAS blockade via angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) has been consistently proven to be an effective and safe strategy for the primary and secondary prevention of cardiovascular disease in patients across a wide spectrum of risk. Although the beneficial effects of RAAS blockade may be due to its effects on central and peripheral blood pressure, there are many additional mechanisms to consider that may contribute additional protection. While a combination of ACE inhibitors and ARBs has not yielded significantly positive results, the newer class of direct renin inhibitors (DRIs) may offer a novel and effective strategy for monotherapy as well as in combination.     

为什么血管紧张素转化酶抑制剂能降低高血压患者死亡率?

最新荟萃分析发现,肾素-血管紧张素(Ang)-醛固酮系统(RAAS)抑制剂能降低高血压患者死亡率,其治疗获益全部源于血管紧张素转化酶(ACE)抑制剂(ACEIs),而非血管紧张素受体拮抗剂(ARBs)。RAAS可以归纳为2条轴:ACE-AngⅡ(1-8)-AT1受体轴和ACE2-Ang(1-7)-Mas受体轴,ACEIs对RAAS的2条轴均发挥良好作用,而ARBs主要作用于前者。各个指南推荐高血压相关心血管疾病治疗优先选择ACEIs,对不能够耐受者选择ARBs。我们应当重视ACEIs在高血压、冠心病、心肌梗死和心力衰竭防治中的应用,目的是降低心血管疾病患病率和死亡率的风险。     

Prevention of macrovascular disease in type 2 diabetic patients: blockade of the renin-angiotensin-aldosterone system

Type 2 diabetes is reaching epidemic proportions throughout the world, which has major health implications as such patients have considerably increased risk of coronary heart disease (CHD). The renin-angiotensin-aldosterone system (RAAS) is involved in a wide range of adverse effects that contribute to the pathogenesis of CHD in diabetic patients, including vascular haemodynamic regulation, oxidative stress and hypertrophy of vascular cells. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) are widely used in clinical practice. In diabetic patients ACE inhibitors and ARBs both effectively lower blood pressure, particularly in combination with low-dose thiazide diuretics, and may be considered first line therapies in the treatment of diabetic hypertension. Additionally they have important renoprotective actions independent of their blood pressure-lowering action, which is of particular benefit in diabetic patients, who are at increased risk of developing nephropathy. ARBs are generally well tolerated, but ACE inhibitor therapy is associated with some side effects such as cough and both may result in hyperkalaemia. Blockade of the RAAS with these agents appears to play an important role not only in protecting from renal disease, but it may also help to reduce morbidity and mortality from certain vascular diseases in diabetic patients.     

Pleiotropic Effects of Inhibitors of the RAAS in the Diabetic Population: Above and Beyond Blood Pressure Lowering

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) are indispensable therapeutic agents for treating hypertension and proteinuria in patients with diabetes mellitus. Studies have shown that the renin-angiotensin-aldosterone system (RAAS) has effects on various organ systems, including the central nervous system, heart, and kidneys. Angiotensin II has major deleterious effects on vascular compliance, vascular relaxation, and plasma markers of inflammation, which are surrogate markers of cardiovascular disease. Evidence is established from major trials that ACE inhibitors and ARB therapy improve these surrogate markers and reduce cardiovascular disease, renal disease, and stroke. Accumulating evidence also supports the newer class of medication, the direct renin inhibitor aliskiren, as beneficial in hypertensive persons with diabetes mellitus. In this article, we review the mechanisms through which inhibitors of the RAAS benefit persons with hypertension and decrease the development of cardiovascular and renal disease above and beyond blood pressure lowering.     

Reducing cardiorenal risk through combination therapy with a direct renin inhibitor

Interruption of the renin-angiotensin-aldosterone system (RAAS) cascade with angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), or more recently direct renin inhibitors (DRIs) is a safe and effective antihypertensive strategy that is in routine clinical use. The clinical utility of these agents in cardiorenal end-organ protection is increasingly being recognized. Although both ACE inhibitors and ARBs demonstrate substantial benefit in patients with cardiovascular and/or renal disease, considerable evidence indicates that they only partially suppress the RAAS pathway due to feedback upregulation of plasma renin activity. With the goal of providing more comprehensive RAAS blockade, combination ACE inhibitor/ARB therapy has been evaluated. However, this approach has not shown the anticipated improvements in composite cardiovascular and renal outcomes and appears to be associated with significant toxicity. Due to a unique mechanism of action, the combination of a DRI with an ACE inhibitor or ARB may represent an effective end-organ-protective therapeutic strategy.     

Efficacy of Angiotensin Receptor Blockers in Cardiovascular Disease

The cardiovascular continuum describes the progression of pathophysiologic events from cardiovascular risk factors to symptomatic cardiovascular disease (CVD) and life-threatening events. Pharmacologic intervention early in the continuum may prevent or slow CVD development and improve quality of life. The renin–angiotensin–aldosterone system (RAAS) is central to the pathophysiology of CVD at many stages of the continuum. Numerous clinical trials of angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) have shown that RAAS blockade provides benefits to patients across the continuum. ARBs are as effective as ACE inhibitors in the treatment of hypertension; however tolerability and adherence to therapy appear to be improved with ARBs. Large clinical trials have shown that ARBs may provide therapeutic benefits beyond blood pressure control in patients with diabetes, heart failure or at risk of heart failure following a myocardial infarction. In addition, ARBs have been shown to provide protective effects in patients with impaired renal function or left ventricular hypertrophy. Additional clinical trials are ongoing to further characterize the role of ARBs in CVD management.     

Angiotensin-converting enzyme inhibitors reduce mortality in hypertension: a meta-analysis of randomized clinical trials of renin-angiotensin-aldosterone system inhibitors involving 158 998 patients

Aims Renin-angiotensin-aldosterone system (RAAS) inhibitors are well established for the reduction in cardiovascular morbidity, but their impact on all-cause mortality in hypertensive patients is uncertain. Our objective was to analyse the effects of RAAS inhibitors as a class of drugs, as well as of angiotensin-converting enzyme (ACE) inhibitors and AT1 receptor blockers (ARBs) separately, on all-cause mortality. Methods and results We performed a pooled analysis of 20 cardiovascular morbidity-mortality trials. In each trial at least two-thirds of the patients had to be diagnosed with hypertension, according to the trial-specific definition, and randomized to treatment with an RAAS inhibitor or control treatment. The cohort included 158 998 patients (71 401 RAAS inhibitor; 87 597 control). The incidence of all-cause death was 20.9 and 23.3 per 1000 patient-years in patients randomized to RAAS inhibition and controls, respectively. Overall, RAAS inhibition was associated with a 5% reduction in all-cause mortality (HR: 0.95, 95% CI: 0.91-1.00, P= 0.032), and a 7% reduction in cardiovascular mortality (HR: 0.93, 95% CI: 0.88-0.99, P= 0.018). The observed treatment effect resulted entirely from the class of ACE inhibitors, which were associated with a significant 10% reduction in all-cause mortality (HR: 0.90, 95% CI: 0.84-0.97, P= 0.004), whereas no mortality reduction could be demonstrated with ARB treatment (HR: 0.99, 95% CI: 0.94-1.04, P= 0.683). This difference in treatment effect between ACE inhibitors and ARBs on all-cause mortality was statistically significant (P-value for heterogeneity 0.036). Conclusion In patients with hypertension, treatment with an ACE inhibitor results in a significant further reduction in all-cause mortality. Because of the high prevalence of hypertension, the widespread use of ACE inhibitors may result in an important gain in lives saved.     

Renin-angiotensin-aldosterone blockade for cardiovascular disease prevention

The renin-angiotensin-aldosterone system (RAAS) plays a significant role in pathophysiology of multiple disease states. RAAS blockade is beneficial in patients with hypertension, acute myocardial infarction, chronic heart failure, stroke, and diabetic renal disease. RAAS blockade with the combination angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) has demonstrated conflicting results in recent clinical trials. This article reviews the latest evidence of isolated ACEI or ARB use, their combination, and the role of aldosterone blockers and direct renin inhibitors in patients at risk, and makes recommendations for their use in the prevention of morbidity and mortality in cardiovascular disease.     

The clinical use of angiotensin-converting enzyme inhibitors

Through an integrative understanding of cardiovascular pathophysiologic characteristics at the multiorgan level, significant achievements in cardiovascular therapeutics have been achieved and enabled the rationale design and development of drugs such as the angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). In this article, we present a detailed review of the physiologic features of the renin-angiotensin-aldosterone system (RAAS), ACE inhibitors and ARB clinical pharmacologic characteristics, and specific diseases in which they are considered to be the standard of the care as supported by important clinical trial data. It is envisioned that an updated and detailed understanding of ACE inhibitors and ARBs will facilitate their successful use in the treatment of heart failure, myocardial infarction, hypertension, renal failure, and diabetic nephropathy.     

The role of ACE inhibitors and angiotensin receptor blockers in the treatment of hypertension and cardiovascular disease

Pharmacologic attenuation of the renin-angiotensin-aldosterone system (RAAS) either through angiotensin-converting enzyme (ACE) inhibition or angiotensin II receptor blockade now occupies a central role in the management of hypertension, diabetes, heart failure, and cardiovascular and renal disease. Although our understanding and use of these agents has expanded significantly over the past decade, the relative and differential benefits of ACE inhibitors and angiotensin receptor blockers (ARBs) are still not entirely clear. The data continue to support the first-line use of ACE inhibitors for all indications. Results for combination ACE inhibitor and ARB therapy in clinical outcome trials have been disappointing and do not support its use. New strategies for RAAS modulation bring hope for further progress in the treatment of hypertensive and cardiovascular disease.     

The renin-angiotensin-aldosterone system: approaches to guide angiotensin-converting enzyme inhibition in patients with coronary artery disease

Drugs that modulate the renin-angiotensin-aldosterone system (RAAS) play an important role in modern cardiovascular prevention strategies. Inhibitors of the RAAS, in particular angiotensin-converting enzyme (ACE) inhibitors, have been proven to be beneficial in specific patient groups, including patients with hypertension, heart failure, diabetes mellitus and stable coronary artery disease. Although clinical trials demonstrated a rather consistent beneficial effect of ACE inhibitors across groups of patients based on clinical characteristics, the variability in treatment response on the individual patient level is extensive. Recent publications suggest that genetic polymorphisms in the RAAS are related to cardiovascular risk. Genetic variability also seems associated with the response to ACE inhibitor therapy, and can probably be used to tailor treatment. This review discusses several approaches to guide ACE inhibitor therapy in patients with coronary artery disease. In addition, the potential impact of pharmacogenetics regarding this particular topic is highlighted.     

Anti-diabetic effect of blockade of the renin-angiotensin system

Diabetes, which is frequently associated with hypertension, accelerates the development of hypertension-induced cardiovascular disease. Thus, the prevention of diabetes is important in the management of hypertension. Recent clinical megastudies have suggested that the blockade of the renin-angiotensin system (RAS) by angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) inhibits new onset of diabetes. Thus, the agents to inhibit the RAS should be beneficial for glucose metabolism. However, the cardiovascular protective effects of ACE inhibitors and ARBs are not always superior to other classes of drugs. Further long-term clinical trials are necessary to clarify the anti-diabetic effect of the RAS-inhibiting agents.     

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.     

Why blockade of the renin-angiotensin system reduces the incidence of new-onset diabetes

Recent trials have suggested that inhibitors of the renin-angiotensin system (RAS), such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs), may reduce the incidence of new-onset diabetes in patients with or without hypertension and at high risk of developing diabetes. In this review, we critically evaluate the evidence from recent clinical trials for such a potential preventive effect of ACE inhibitors and ARBs, including a meta-analysis of these recent trials. The reduced incidence of diabetes in patients at high risk of developing diabetes by ACE inhibitors or ARBs has been explained by haemodynamic effects, such as improved delivery of insulin and glucose to the peripheral skeletal muscle, and non-haemodynamic effects, including direct effects on glucose transport and insulin signalling pathways, all of which decrease insulin resistance. There is now evidence that the pancreas may contain an in situ active RAS, which appears to be upregulated in an animal model of type 2 diabetes. Thus, ACE inhibitors and ARBs may act by attenuating the deleterious effect of angiotensin II on vasoconstriction, fibrosis, inflammation, apoptosis and beta-cell death in the pancreas, thereby protecting a critical beta-cell mass essential for insulin production. New evidence is presented that ACE inhibitors and ARBs may delay or prevent the development of insulin resistance and diabetes, for which novel mechanisms are suggested. The actions of agents that interrupt the RAS on insulin resistance, obesity and diabetes warrant further investigation in other animal models. Prospective clinical studies with the primary endpoint of the prevention of diabetes are now indicated to (i) further explore whether the inhibitors of the RAS are superior compared to other antihypertensive agents such as calcium channel blockers (CCBs) and (ii) to evaluate the potential beneficial effects of combination antihypertensive regimens on the development of diabetes.     

Antidiabetic mechanisms of angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists: beyond the renin-angiotensin system

Several lines of evidence suggest that angiotensin-converting enzyme (ACE) inhibitors and some angiotensin II receptor blockers (ARBs) may improve insulin sensitivity and decrease the risk for type 2 diabetes. It is widely assumed that the potential antidiabetic properties of these agents are largely mediated by their ability to interfere with the adverse metabolic effects of angiotensin II. However, recent studies suggest that ACE inhibitors might improve glucose metabolism primarily through effects on kinin-nitric oxide pathways. In addition, one ARB in particular, telmisartan, has been found to effectively activate the peroxisome proliferator activated receptor gamma (PPARgamma), a well-known target for insulin-sensitizing, antidiabetic drugs. Thus, the beneficial metabolic effects of some ACE inhibitors and ARBs may go well beyond their effects on the renin-angiotensin system. Moreover, the identification of telmisartan as a unique angiotensin II receptor antagonist with selective PPARgamma modulating ability suggests new opportunities for developing third-generation ARBs and PPARgamma activators, with enhanced potential for treating hypertension, diabetes and the metabolic syndrome.     

Endothelial Damage and Regeneration: The Role of the Renin-Angiotensin-Aldosterone System

The renin-angiotensin-aldosterone system (RAAS) is part of the blood pressure regulating system. Its main effector peptide is angiotensin II (Ang II). Although it may induce hypertension, the proinflammatory, profibrotic, and prothrombotic effects are mainly mediated by effects of Ang II on the cellular and molecular level that are independent of blood pressure. Therefore, pharmacotherapeutic intervention within the RAAS is an important treatment modality for patients suffering from cardiovascular diseases, even those who are not hypertensive. In addition to the blood pressure lowering and vasculoprotective (pleiotropic) effects of angiotensin II type 1 (AT₁) receptor blockers (ARBs), and angiotensin-converting enzyme (ACE) inhibitors, regenerative progenitor cell therapy emerges as an auxiliary therapy to improve regeneration of the vascular endothelium. This review focuses on the growing knowledge about regenerating vascular cells, their response to RAAS effectors, and RAAS-modulating pharmacotherapy in the context of endothelial cell damage and regeneration.     

Suppression of the renin-angiotensin-aldosterone system in chronic heart failure: choice of agents and clinical impact

Chronic heart failure (CHF) has taken on epidemic proportions in the United States, with approximately 550,000 new cases annually. With the evolution of pharmacotherapy targeting neurohormonal pathways over the past 2 decades, the annual mortality in subjects with New York Heart Association (NYHA) class IV has dramatically improved from 52% in the seminal CONSENSUS trial to less than 20% in more recent trials in CHF. Suppression of the renin-angiotensin system (RAS) with various angiotensin-converting enzyme (ACE) inhibitors has been proven to save lives in several large-scale trials of CHF, and all of them can be used at doses tested in clinical trials without clear preference of one over another. Angiotensin receptor blockers (ARBs) can be used in place of ACE inhibitors in the case of ACE inhibitor intolerance with comparable results. However, some inconsistencies exist between trials with ARBs, and it is uncertain if the ARBs tested in clinical trials provide comparable clinical benefit whether used in place of or in combination with ACE inhibitors. Once ACE inhibition has been started, beta blockade should follow for all subjects with symptomatic CHF. Triple neurohormonal blockade can then be accomplished with the addition of an aldosterone receptor or ARB. Regardless of the exact agent used or sequence of initiation, the critical importance of careful monitoring of neurohormonal blockade cannot be overstated. Renal failure and hyperkalemia are the most important complications of suppression of the renin-angiotensin-aldosterone system (RAAS), and an increase in hospital admissions and death from hyperkalemia after publication of the RALES trial illustrates the danger of "casual" use of neurohormonal blockers. In light of the tremendous benefits of neurohormonal blockade, the only conclusion from these data is to initiate RAAS-blocking agents following the safety precautions tested in the respective clinical trials.     

The renin angiotensin system as a therapeutic target to prevent diabetes and its complications

The role of the RAAS in development and maintenance of blood pressure is well established.In addition, the deleterious effects of angiotensin II on the heart, vasculature, and kidneys have been clearly defined. There seems to be a close relationship between endothelial dysfunction, insulin resistance (a precursor to diabetes and coronary artery disease) and angiotensin II. The signaling pathways for insulin in the vascular wall interacts with the angiotensin signaling, giving rise to potential mechanisms for development of diabetes and resulting harmful effects. A large number of clinical trials using ACE inhibitors or ARBs have shown significant reduction in secondary endpoints in the development of new onset of diabetes. Ongoing prospective studies involving ARBs (eg, the Nateglinide and Valsartan Impaired Glucose Tolerance Outcomes Research trial) and ACE inhibitors (eg, the Diabetes Re-duction Assessment with Ramipril and Rosiglita-zone Medication trial) are testing the ability of certain agents to prevent type 2 diabetes. In the meantime, it is important to recognize insulin resistance and metabolic syndrome as entities that increase the risk for cardiovascular disease. In addition to lifestyle modifications, managing endothelial dysfunction and protecting the vasculature will help prevent diabetes and cardiovascular disease.     

Treating patients for cardiovascular protection: combination therapy to achieve complete renin-angiotensin system blockade

Inhibition of the renin-angiotensin system (RAS) with angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) is a proven antihypertensive strategy. Understanding of the pathophysiologic effects of chronic RAS activation and clinical data indicate that RAS inhibition may exert beneficial effects in addition to blood pressure reduction. Studies indicate that monotherapy with ACE inhibitors and ARBs slows progression of diabetic and non-diabetic renal disease. Vascular protective effects of RAS inhibition have also been demonstrated in patients at high risk for cardiovascular events in the absence of significant blood pressure elevation or left ventricular dysfunction. Combining the complementary effects of ACE inhibitors and ARBs to achieve more complete RAS blockade is a promising approach to further reducing cardiovascular risk. This review will present the rationale for dual RAS inhibition, clinical data relating to its efficacy, and ongoing studies designed to evaluate its utility in patients at high risk for cardiovascular events.     

Sind alle Antihypertensiva nephroprotektiv?

Blood pressure, together with proteinuria, represents one of the most important factors in the progression of chronic renal failure (CRF). Antihypertensive therapy is beneficial to slow down the progression of a variety of chronic renal diseases, no matter what the cause. Intraglomerular hypertension, increased glomerular permeability and proteinuria should be identified, since they can be treated to prevent or minimize further glomerular injury.But not all antihypertensive drugs are equally effective to prevent the progression of CRF. Recent large trials indicate that blood pressure lowering obtained by intervention in the renin-angiotensin-aldosterone system (RAAS) has an additive renoprotective effect in diabetic and nondiabetic renal diseases. In nondiabetic patients, the AIPRI and REIN studies support that angiotensin-converting enzyme (ACE) inhibitors have a long-term renoprotective effect. The benefits of ACE inhibitors can be demonstrated even in patients who are not hypertensive. Angiotensin II receptor antagonists are shown to be renoprotective in type 2 diabetics (RENAAL and IDNT). However, whether these renoprotective effects are due to blood pressure reduction or due to the specific pharmacologic RAAS blockade is still a matter of debate. This discussion is still open, because the reduction in blood pressure levels was lower in patients treated with a drug that interferes with the RAAS compared with other antihypertensive regimens. It is concluded that both ACE inhibitors and AT II receptor antagonists are lowering the intraglomerular pressure independent of any change in systemic blood pressure by dilatation of the efferent arteriole of the glomerulus. These additional nonpressure-related effects may protect renal function by their antiproteinuric effect. In addition, beneficial effect of ACE inhibitors are related to reduction of AT II, which has potent proinflammatory effects independent of its hemodynamic influences.Other drugs, such as diuretics, beta blockers, and hydralazine, do not induce efferent dilatation and, therefore, may be less likely to reverse intraglomerular hypertension. For example, hydralazine and nifedipine appear to produce prominent afferent or preglomerular arteriolar dilatation. This will allow more of the systemic pressure to be transmitted to the glomerulus. Therefore, short-acting dihydropyridine calcium channel blockers (CCB) are not recommended. By comparison, long-acting dihydropyridines such as diltiazem and verapamil are less potent vasodilators and may primarily decrease the resistance of the efferent arteriole, similar to the ACE inhibitors. They may have an antiproteinuric activity. Yet, there is lack of large prospective randomized trials.A beta blocker as antihypertensive agent is indicated as second- or third-line drug especially in patients with additional cardiovascular disease. Other antihypertensive drugs can be added as necessary to achieve the treatment goals for arterial hypertension. The use of a diuretic will often be helpful in patients who already have renal insufficiency, since fluid overload is an important cause of hypertension and may also enhance the effectiveness of drugs that interfere with the RAAS. alpha(1)-receptor or sympathetic blockers are further possible drugs for combination antihypertensive therapy.