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

Impairment of myocardial blood flow reserve in patients with asymptomatic left ventricular dysfunction: effects of ACE-inhibition with perindopril

Myocardial blood flow (MBF) reserve is impaired in patients with symptomatic chronic heart failure. Whether this is already present in asymptomatic left ventricular (LV) dysfunction, and whether it is affected by angiotensin converting enzyme (ACE) inhibition, is unknown. We examined MBF in 20 patients with asymptomatic LV dysfunction and compared them to healthy volunteers. MBF (reserve) was assessed with positron emission tomography (PET) and N-13 ammonia at rest, during dipyridamole stress test (DST) and during cold pressor test (CPT). Further, in the LV-dysfunction group, we studied the effects of 3 months treatment with ACE inhibition with a second PET study. Patients were randomized double-blind to perindopril 4 mg daily or placebo. MBF at rest was similar in controls and patients. DST-induced MBF reserve, however, was decreased in patients vs. controls (1.71+/-0.2 vs. 2.62+/-0.5, respectively p < 0.05). Also CPT-induced MBF was lower in patients (1.14+/-0.06 vs. 1.23+/-0.03, p < 0.05). After 3 months double-blind treatment, CPT-induced MBF decreased in the placebo group (from 1.12+/-0.02 to 0.93+/-0.06), but was preserved in the perindopril group (from 1.16+/-0.08 to 1.14+/-0.08 shifts from baseline: -0.19+/-0.05 vs. -0.02+/-0.07 respectively p = 0.07). This was compatible with a trend to a smaller increase in coronary vascular resistance during CPT (1.23+/-0.08 vs. 1.03+/-0.06, placebo vs. perindopril, p = 0.06). In patients with asymptomatic LV dysfunction, MBF, both after vasodilation and after CPT, is already impaired. ACE inhibition with perindopril during this short-term treatment had no significant effects.

Thromboembolism in heart failure, old ideas and new challenges

Until now, the administration of antithrombotic therapy in patients with congestive heart failure has not been well codified. The incidence of thromboembolic complication, such as stroke, peripheral or pulmonary embolism, is regarded as too low to justify the use of anticoagulation in non-selected patients. However, other thrombotic complications may occur especially in patients with ischemic heart failure and represent potential targets for antithrombotic therapy. The objective of this paper is to review the available evidence in the absence of the results of large ongoing trials.

Impact of postprandial hypertriglyceridemia on vascular responses in patients with coronary artery disease: effects of ACE inhibitors and fibrates

We analyzed vascular responses (endothelial function, oxidant stress) to postprandial hypertriglyceridemia (PHTG) in patients with coronary artery disease (CAD) to reveal potential therapeutical effects of angiotensin converting enzyme inhibition (ACE-I) and of lipid lowering (fibrate). The study population (n=39, mean age: 60 years) consisted of four groups, all of which had angiographically documented CAD. A high fat group (n=9) consumed a high fat meal, a low fat group (n=9) a low fat meal, and ACE-I (n=10) or fibrate (n=11) groups consumed a high fat meal plus lisinopril or fenofibrate. Serum triglycerides (TG) increased significantly 2 h after eating a test meal in all groups with the exception of the low fat group. In the high and low fat groups changes of serum TG were positively correlated (r=0.664, P<0.005) with changes of phorbol ester-activated leukocyte superoxide anion radical (O(2-.)) formation and were negatively correlated (r=-0.488, P<0.05) with flow-mediated brachial artery dilation (FMD). There was a negative correlation (r=-0.419, P=0.094) between FMD and changes of O(2-.) formation in the high and low fat groups. In the ACE-I and fibrate groups, O(2-.) formation decreased 2 h after eating a test meal (from 5.34+/-1.01 to 3.81+/-1.15 nmol/10(6)cells per min, P<0.01, and from 4.66+/-0.91 to 4.26+/-0.97 nmol/10(6)cells per min, P=0.374, respectively). However, endothelial function did not show any significant changes 2 h after eating a test meal in all groups. PHTG increases oxidant stress and further deteriorates endothelial function, even in patients with CAD. Both ACE-I and fibrates have an antioxidant effect but no acute beneficial effects in terms of endothelial function under conditions of PHTG in CAD patients.

Does aspirin attenuate the effect of angiotensin-converting enzyme inhibitors in hypertension or heart failure?

There is a wealth of data that suggests an important interaction between aspirin and angiotensin-converting enzyme inhibitors in patients with chronic stable cardiovascular disease. The interaction is less obvious in the postinfarction setting, possibly reflecting the fact that many patients stop their aspirin therapy within a few months of such an event. An interaction is biologically plausible, because there is considerable evidence that angiotensin-converting enzyme inhibitors exert important effects through increasing the production of vasodilator prostaglandins, whereas aspirin blocks their production through inhibition of cyclooxygenase, even at low doses. There is some evidence that low-dose aspirin may raise systolic and diastolic blood pressure. There is also considerable evidence that aspirin may entirely neutralize the clinical benefits of angiotensin-converting enzyme inhibitors in patients with heart failure. In addition, aspirin may have an adverse effect on outcome in patients with heart failure that is independent of any interaction with angiotensin-converting enzyme inhibitors, possibly by blocking endogenous vasodilator prostaglandin production and enhancing the vasoconstrictor potential of endothelin. The evidence is not sufficient to justify advising long-term aspirin therapy for patients with cardiovascular disease in general, and for those with heart failure in particular. Thus, the lack of evidence of benefit with aspirin in patients with heart failure and coronary disease, along with growing evidence that aspirin is directly harmful in patients with heart failure and that aspirin may negate the benefits of angiotensin-converting enzyme inhibitors suggest that, unless there is an opportunity to randomize the patient into a study of antithrombotic strategies, then aspirin should be withdrawn or possibly substituted with an anticoagulant or an antiplatelet agent that does not block cyclooxygenase. In contrast, there is fairly robust evidence for a benefit of both aspirin and angiotensin-converting enzyme inhibitors during the first 5 weeks after a myocardial infarction, with little evidence of an interaction. The combination of aspirin and angiotensin-converting enzyme inhibitors is warranted during this period, after which discontinuation or substitution of aspirin with another agent should be considered.

Effects of ramipril on coronary events in high-risk persons: results of the Heart Outcomes Prevention Evaluation Study

BACKGROUND

In trials of patients with left ventricular dysfunction or heart failure, ACE inhibitor use was unexpectedly associated with reduced myocardial infarction (MI). Using the Heart Outcomes Prevention Evaluation (HOPE) trial data, we tested prospectively whether ramipril, an ACE inhibitor, could reduce coronary events and revascularization procedures among patients with normal left ventricular function.

METHODS AND RESULTS

In the HOPE trial, 9297 high-risk men and women, >/=55 years of age with previous cardiovascular disease or diabetes plus 1 risk factor, were randomly assigned to ramipril (up to 10 mg/d), vitamin E (400 IU/d), their combination, or matching placebos. During the mean follow-up of 4.5 years, there were 482 (10.4%) patients with clinical MI and unexpected cardiovascular death in the ramipril group compared with 604 (12.9%) in the placebo group [relative risk reduction (RRR), 21% (95% CI) (11,30); P<0.0003]. Ramipril was associated with a trend toward less fatal MI and unexpected death [4.0% versus 4.7%; RRR, 16% (-3, 31)] and with a significant reduction in nonfatal MI [5.6% versus 7.2%; RRR, 23% (9,34)]. Risk reductions in MI were documented in participants taking or not taking beta-blockers, lipid lowering, and/or antiplatelet agents. Although ramipril had no impact on hospitalizations for unstable angina [11.9% versus 12.2%; RRR, 3% (-9,14)], it reduced the risk of worsening and new angina [27.2% versus 30.0%; RRR, 12% (5,18); P<0.0014] and coronary revascularizations [12.5% versus 14.8%; RRR, 18%; (8,26) P<0.0005].

CONCLUSIONS

In this high-risk cohort, ramipril reduced the risk of MI, worsening and new angina, and the occurrence of coronary revascularizations.

A remarkable medical story: benefits of angiotensin-converting enzyme inhibitors in cardiac patients

The development of angiotensin-converting enzyme inhibitors (ACE inhibitors) has been one of the most remarkable stories in the treatment of cardiovascular diseases. Angiotensin converting enzyme inhibitors have several acute and sustained hemodynamic effects that are beneficial in the presence of left ventricular (LV) dysfunction. They increase cardiac output and stroke volume and reduce systemic vascular resistance as well as pulmonary capillary wedge pressure. The hemodynamic benefits are associated with improvement in the signs and symptoms of congestive heart failure (CHF) as well as decreased mortality, regardless of the severity of CHF. In patients with asymptomatic LV dysfunction, therapy with ACE inhibitors prevented the development of CHF and reduced hospitalization and cardiovascular death. They also increase survival when administered early after an acute myocardial infarction (MI). Most recently, ACE inhibition was associated with improved clinical outcomes in a broad spectrum of high-risk patients with preserved LV function. The mechanism of ACE inhibitors benefits is multifactorial and includes prevention of progressive LV remodeling, prevention of sudden death and arrhythmogenicity and structural stability of the atherosclerotic process. Evidence suggests that ACE inhibitors are underutilized in patients with cardiovascular diseases. Efforts should be directed to prescribe ACE inhibitors to appropriate patients in target doses. It is reasonable to believe that ACE inhibitors have a class effect in the management of LV dysfunction with or without CHF and acute MI. Whether the same is true for ACE inhibitors in the prevention of ischemic events is not known yet.

Bradykinin stimulates the release of tissue plasminogen activator in human coronary circulation: effects of angiotensin-converting enzyme inhibitors

OBJECTIVES

The goal of this study was to determine: 1) whether bradykinin (BK) directly stimulates tissue plasminogen activator (tPA) secretion in human coronary circulation, and 2) whether angiotensin-converting enzyme (ACE) inhibition favorably alters the fibrinolytic balance regulated by BK.

BACKGROUND

Bradykinin is a potent stimulator of tPA secretion in endothelial cells; however, the effect of BK on tPA release in the human coronary circulation has not been studied.

METHODS

Fifty-six patients with atypical chest pain were randomly assigned to two groups: 25 patients were treated with the ACE inhibitor enalapril (ACE inhibitor group), and 31 were not treated with ACE inhibitors (non-ACE inhibitor group). Graded doses of BK (0.2, 0.6, 2.0 microg/min), acetylcholine (ACh) (30 microg/min) and papaverine (PA) (12 mg) were administered into the left coronary artery. Coronary blood flow (CBF) was evaluated by Doppler flow velocity measurement. Blood samples were taken from the aorta (Ao) and the coronary sinus (CS).

RESULTS

Bradykinin induced similar increases in CBF in both groups. The net tPA release induced by BK was dose-dependently increased in both groups, and the extent of that increase in the ACE inhibitor group was greater than that in the non-ACE inhibitor group. Bradykinin did not alter plasminogen activator inhibitor-1 (PAI-1) levels in the Ao or CS in either group. Neither ACh nor PA altered tPA levels or PAI-1 levels in either group.

CONCLUSIONS

Intracoronary infusion of BK stimulates tPA release without causing any change in PAI-1 levels in the human coronary circulation. In addition, this effect of BK is augmented by an ACE inhibitor.

Chronic blockade of angiotensin II action prevents glomerulosclerosis, but induces graft vasculopathy in experimental kidney transplantation

Long-term renin-angiotensin system blockade is beneficial in a variety of renal diseases. This study examines the long-term (34 weeks) effects of the angiotensin-converting enzyme inhibitor lisinopril and the angiotensin II receptor type I blocker L158,809 in the Fisher to Lewis rat model of chronic renal transplant failure. Treatment in allografted rats with lisinopril or L158,809 was initiated 10 days after transplantation, or at the time when proteinuria exceeded 50 mg/24 h. Untreated allografts and syngrafts served as controls. In contrast to syngrafts, untreated allografts developed proteinuria, hypercholesterolaemia, interstitial damage, and glomerulosclerosis. Lisinopril or L158,809 treatment in allografts starting at day 10 after transplantation completely prevented this, with the exception of interstitial damage, but this treatment also caused a reduction in blood pressure and renal function. Moreover, the intimal surface area of the renal arteries was dramatically increased in allografts treated with either lisinopril or L158,809 compared with untreated allografted rats. Treatment once proteinuria had developed was less effective in preventing glomerulosclerosis, but also caused less intimal expansion. Thus, chronic renin-angiotensin system blockade preserves glomerular morphology in the absence of proteinuria, but enhances intimal hyperplasia and reduces renal function in experimental transplantation. In view of these results, it should be questioned whether such treatment benefits renal transplant patients in the long term.

The Quinapril Ischemic Event Trial (QUIET): evaluation of chronic ace inhibitor therapy in patients with ischemic heart disease and preserved left ventricular function

Angiotensin-converting enzyme inhibitors improve endothelial function, inhibit experimental atherogenesis, and decrease ischemic events. The Quinapril Ischemic Event Trial was designed to test the hypothesis that quinapril 20 mg/day would reduce ischemic events (the occurrence of cardiac death, resuscitated cardiac arrest, nonfatal myocardial infarction, coronary artery bypass grafting, coronary angioplasty, or hospitalization for angina pectoris) and the angiographic progression of coronary artery disease in patients without systolic left ventricular dysfunction. A total of 1,750 patients were randomized to quinapril 20 mg/day or placebo and followed a mean of 27 +/- 0.3 months. The 38% incidence of ischemic events was similar for both groups (RR 1.04; 95% confidence interval 0.89 to 1.22; p = 0.6). There was also no significant difference in the incidence of patients having angiographic progression of coronary disease (p = 0.71). The rate of development of new coronary lesions was also similar in both groups (p = 0.35). However, there was a difference in the incidence of angioplasty for new (previously unintervened) vessels (p = 0.018). Quinapril was well tolerated in patients after angioplasty with normal left ventricular function. Quinapril 20 mg did not significantly affect the overall frequency of clinical outcomes or the progression of coronary atherosclerosis. However, the absence of the demonstrable effect of quinapril may be due to several limitations in study design.

Angiotensin II and atherosclerosis

Numerous clinical and laboratory data are now available supporting the hypothesis that the renin-angiotensin system is mechanistically relevant in the pathogenesis of atherosclerosis. The traditional role of the renin-angiotensin system in the context of blood pressure regulation has been modified to incorporate the concept that angiotensin II (Ang II) is a potent proinflammatory agent. In vascular cells, Ang II is a potent stimulus for the generation of reactive oxygen species. As a result, Ang II upregulates the expression of many redox-sensitive cytokines, chemokines, and growth factors that have been implicated in the pathogenesis of atherosclerosis. Extensive data now confirm that inhibition of the renin-angiotensin system inhibits atherosclerosis in animal models as well as in humans. These studies provide mechanistic insights into the precise role of Ang II in atherosclerosis and suggest that pharmacologic interventions involving the renin-angiotensin system may be of fundamental importance in the treatment and prevention of atherosclerosis.

Angiotensin, fibrinolysis, and vascular homeostasis

There is strong evidence that imbalance of the fibrinolytic system is involved in the pathogenesis of ischemic cardiovascular events. A reduction in fibrinolytic function may also mediate part of the adverse response of the vasculature to conditions of low nitric oxide production. Because reduced nitric oxide activity predisposes to the development of atherosclerosis, imbalance of the fibrinolytic system is heavily implicated in the development of cardiovascular pathology. The renin-angiotensin system exerts substantial control over the fibrinolytic system, and pharmacologic interventions that reduce the activity of angiotensin II also have favorable effects on fibrinolytic balance and on the incidence of adverse cardiovascular events. This review summarizes the evidence for a link between activation of the renin-angiotensin system, fibrinolytic imbalance, and cardiovascular pathology.

Anti-ischemic effects of angiotensin-converting enzyme inhibitors: a future therapeutic perspective

The renin-angiotensin system and angiotensin-converting enzyme (ACE) are increasingly being implicated in the pathogenesis of coronary artery disease and its sequelae and the potential of ACE inhibitors to protect the heart is a topic that has emerged recently as a matter for scientific discussion. Experimental and clinical studies have shown the beneficial effects of ACE inhibitors on the metabolism, function and structure of healthy and damaged hearts and these data support the concept of both primary and secondary cardioprotection with this class of drugs. Animal studies have demonstrated the potential beneficial effects of ACE inhibition at a variety of sites, including improvement of endothelial function, inhibition of platelet aggregation, prevention of atherosclerotic lesions and inhibition of myointimal proliferation, extending the concept to a more general definition of cardiovascular protection with ACE inhibitors involving both the heart and the vessels. ACE inhibitors prevent stimulation of smooth muscle cell angiotensin-II (A-II) receptors, thereby blocking both contractile and proliferative actions of A-II. In addition, ACE inhibition of kininase inhibits the breakdown of bradykinin, a direct stimulant of nitric oxide release from the intact endothelial cell. Thus, at the cellular level ACE inhibition shifts the balance of ongoing mechanisms in favour of those promoting vasodilatory, anti-aggregatory, antithrombotic and antiproliferative effects. Although these data have not all been validated in human studies, the reduction of ischemic events in studies of ACE inhibition in left ventricular dysfunction (LVD) and, more recently, also in patients without LVD, cannot be explained solely by improved hemodynamics, and it is possible that actions on the endothelium, the atherosclerotic process and platelets are at least in part responsible. So, the available data underlie the potential benefits of ACE inhibition in the field of ischemic heart disease and atherosclerosis; the results of ongoing studies in humans looking more directly at the influence of ACE inhibitors in this setting are awaited with interest.

Anti-ischemic potential of drugs related to the renin-angiotensin system

Actions mediated by the renin-angiotensin system may be inhibited at various levels: renin itself may be inhibited, angiotensin-I (A-1) conversion to angiotensin-II (A-II), or binding of A-II at the A-II type 1 (A-II1) receptor. The angiotensin-converting enzyme (ACE) inhibitors and the A-II1 receptor antagonists are now clinically established. Because ACE is a relatively unspecific peptidase which catalyses the breakdown of A-I, bradykinin and neuropeptides like substance P and neurotensin, the effects of ACE inhibitors go far beyond the prevention of A-II production. On the other hand, in certain tissues like vascular and cardiac tissue, A-II is produced by other enzymes, for instance chymase, and ACE inhibitors do not consistently prevent A-II production. The action of A-II1 receptor antagonists may also not be confined to prevention of binding of A-II at the A-II1 receptor, as by rebound more A-II may bind at the A-II type 2 (A-II2) receptor and thus mediate until now not well defined effects. Thus, anti-ischemic actions of these drugs may be related to multiple mechanisms. Inhibition of A-II effects at the A-II1 receptor may prevent systemic and coronary vasoconstriction and growth effects of A-II on various cell types. In addition, A-II may potentiate, by pre- and postsynaptic mechanisms, activation of the sympathetic nervous system. Prevention of breakdown of bradykinin, substance P and neurotensin may result in direct vasodilation or release of nitrous oxide from the endothelium. Thus, growth-inhibiting effects may also be mediated. All these mechanisms seem to direct to a reduction of cardiac load by vasodilation and to a limitation of cardiovascular cell growth. While the systemic circulating renin-angiotensin system is probably responsible for control of cardiac load, local systems seem to control cell growth. Systemic effects seem to depend on activation of the renin-angiotensin system which has been shown in various ischemic syndromes. Activation of various components of the renin-angiotensin system has been demonstrated in myocardial ischemia, acute myocardial infarction and coronary occlusion and reperfusion models as well as in chronic left ventricular dysfunction post-myocardial infarction. While animal models of stress-induced myocardial ischemia have revealed predominantly positive results, clinical studies, which mostly were small and not well controlled, were equivocal. Large clinical trials with ACE inhibitors in acute myocardial infarction showed small benefits over placebo. Hypotension seems to be a critical side-effect in this situation. Experimental models show protective effects of both ACE inhibitors and A-II1 receptor antagonists in the situation of ischemia and reperfusion. New data on large clinical trials in patients at risk of cardiovascular events but normal left ventricular function demonstrate clear benefits of an ACE inhibitor. Large clinical trials in patients with chronic left ventricular dysfunction post-myocardial infarction show reduction of ischemic events.

Beyond remodeling: a new paradigm for angiotensin-converting enzyme inhibitors following myocardial infarction

Angiotensin converting enzyme (ACE) inhibitors, originally designed to treat hypertension, were quickly demonstrated to confer hemodynamic and survival benefit to patients with congestive heart failure. Extending this paradigm to patients with left ventricular dysfunction (LVD) post-myocardial infarction (MI), ACE inhibitors were shown to attenuate ventricular remodeling and reduce mortality. An unexpected finding that ACE inhibitors could reduce the incidence of myocardial infarction, prompted enormous interest in their anti-ischemic potential. Indeed, a significant body of experimental literature supports the concept that ACE inhibitors have direct anti-atherosclerotic and anti-ischemic effect. Recent clinical trials have shown that ACE inhibitors confer significant protection from ischemic events.

Effects of quinapril on clinical outcome after coronary artery bypass grafting (The QUO VADIS Study). QUinapril on Vascular Ace and Determinants of Ischemia

The QUO VADIS study was designed to explore whether 1 year of angiotensin-converting enzyme inhibition with quinapril (40 mg/day) would decrease ischemia in patients who underwent coronary artery bypass grafting (CABG). Patients (n = 149) scheduled for CABG were randomized 4 weeks before surgery. Study medication was used from randomization up to 1 year after CABG. Exercise testing was performed at randomization; the exercise test was repeated 1 year after CABG and patients underwent 48-hour Holter monitoring. Clinical ischemic events were recorded and defined as death, revascularization, myocardial infarction, recurrence of angina pectoris, ischemic stroke, or transient ischemic attack. Baseline characteristics were similar between groups. Total exercise time increased overall by 75 +/- 76 seconds 1 year after CABG (placebo +79 +/- 75 seconds, quinapril +72 +/- 79 seconds, p = 0.6). All patients had ischemic ST-segment changes at randomization; 33% of patients had ischemic ST-segment changes 1 year after CABG (placebo 29%, quinapril 37%, p = 0.4). On Holter monitoring, the number of patients experiencing > or = 1 episodes of ischemia was equal in both groups. Treatment with quinapril significantly reduced clinical ischemic events after CABG: 15% in patients on placebo versus 4% of patients on quinapril (hazard ratio 0.23, 95% confidence interval 0.06 to 0.87, p = 0.02). Long-term quinapril treatment significantly reduced clinical ischemic events within 1 year after CABG, although ischemia at exercise testing and Holter monitoring was unchanged.

What is the optimal medical management of ischemic heart failure?

Ischemic heart disease is an important and common contributor to the development of heart failure. Theoretically, all patients with heart failure may benefit from treatment designed to retard progressive ventricular dysfunction and arrhythmias. Patients with ischemic heart disease may also theoretically benefit from the relief of ischemia, the prevention of coronary occlusion, and revascularization. However, there is little evidence to show that the presence or absence of coronary disease modifies the benefits of effective treatments such as angiotensin-converting enzyme inhibitors and beta-blockers. Moreover, there is no evidence that treatment directed specifically at myocardial ischemia or coronary disease alters outcome in patients with heart failure. Treatments aimed at relieving painless myocardial ischemia have not been shown to alter prognosis. Lipid-lowering therapy is theoretically attractive for patients with heart failure and coronary disease; however, theoretical concerns also exist about the safety of such agents, and patients with heart failure have been excluded from large outcome studies very effectively. Some agents, such as aspirin, designed to reduce the risk of coronary occlusion seem ineffective or harmful in patients with heart failure, although warfarin may be safe and possibly effective. There is no evidence yet that revascularization improves prognosis in patients with heart failure, even in patients who are shown to have extensive myocardial hibernation. On current evidence, revascularization should be reserved for the relief of angina. Large-scale, randomized controlled trials are currently underway that are investigating the role of specific treatments targeted at coronary syndromes. The Carvedilol Hibernation Reversible Ischemia Trial: Marker of Success study is investigating the effects of carvedilol in a large cohort of patients with and without hibernating myocardium. The Warfarin and Antiplatelet Therapy in Chronic Heart Failure study is comparing the efficacy of aspirin, clopidogrel, and warfarin. The Heart Revascularization Trial-United Kingdom study is assessing the effect of revascularization on mortality in patients with heart failure and myocardial hibernation. Smaller scale studies are assessing the safety and efficacy of statin therapy in patients with heart failure. Only once the outcomes to these and other planned trials are known can the medical community know how best to treat their patients.

Unstable angina pectoris and non-Q-wave myocardial infarction

Unstable angina pectoris and non-Q-wave myocardial infarction are clinical syndromes that share many pathophysiologic and clinical features. In the spectrum of coronary artery disease, these syndromes lie between chronic stable angina and Q-wave myocardial infarction. Although both conditions are associated with significant morbidity and mortality, patients presenting with these syndromes can be further risk stratified into higher and lower risk based on a number of readily available clinical features and biochemical parameters. Such risk stratification can allow for more tailored treatment and better resource allocation. Although routine early coronary angiography and revascularization has not been shown to be superior to conservative management, certain high-risk patients may benefit from a more aggressive strategy. Medical therapy with the use of antiplatelet, anticoagulant, and antiischemic agents remains the cornerstone of emergent treatment for patients presenting with these syndromes. The recent demonstration of a reduction in both morbidity and mortality with the glycoprotein IIb/IIIa antagonists has further expanded the armamentarium of available agents. Following initial stabilization, risk stratification with stress testing can help identify patients with a large residual ischemic burden who may benefit from coronary angiography with revascularization if feasible.

Prevention of atherosclerosis by specific AT1-receptor blockade with candesartan cilexetil

Several studies indicate that blockade of the renin-angiotensin-aldosterone system (RAAS) can prevent atherosclerosis and vascular events, but the precise mechanisms involved are still unclear. In this study, we investigated the effect of the AT 1-receptor blocker, candesartan, in the prevention of atherosclerosis in Watanabe heritable hyperlipidaemic (WHHL) rabbits and also the effect of AT1-receptor blockade in the uptake of oxidised LDL by macrophage cell cultures. In the first set of experiments, 12 WHHL rabbits were randomly assigned to three groups: placebo, atenolol 5 mg/kg daily or candesartan 2 mg/kg daily for six months. Compared with controls and atenolol-treated rabbits, candesartan treatment resulted in a significant 50-60% reduction of atherosclerotic plaque formation and a 66% reduction in cholesterol accumulation in the thoracic aorta. Studies in macrophage cultures indicated that candesartan prevented uptake of oxidised LDL-(oxLDL)-cholesterol by cultured macrophages. Candesartan inhibited the uptake of oxLDL in a dose-dependent manner, reaching a maximum inhibition of 70% at concentrations of 5.6 µg/ml. Further studies in other animal models and well-designed trials in humans are warranted to further explore the role of AT1-receptor blockade in the prevention of atherosclerosis.

Effects of early use of atenolol or captopril on infarct size and ventricular volume: A double-blind comparison in patients with anterior acute myocardial infarction

BACKGROUND

beta-Blockers and ACE inhibitors reduce early mortality when either one is started in the first hours after myocardial infarction (MI). Considering the close correlation between morphological changes and prognosis, we aimed to investigate whether the benefit of both beta-blockers and ACE inhibitors might reside in a similar protective effect on infarct size or ventricular volume.

METHODS AND RESULTS

In a randomized, double-blind comparison between early treatment with captopril or atenolol in 121 patients with acute anterior MI, both drugs showed a similar reduction in mean blood pressure. However, only the atenolol-treated patients showed a significant early reduction in heart rate. Infarct size, obtained from the perfusion defect in resting single photon emission imaging, was higher in captopril-treated patients than in atenolol-treated patients: 29.8+/-12% versus 20.8+/-12% (P:<0.01) by polar map and 28.3+/-13% versus 20.0+/-13% (P:<0.01) by tomography. Changes from baseline to 1 week and to 3 months in ventricular end-diastolic volume, assessed by echocardiography, were as follows: 58+/-14 versus 64+/-19 (P<0.05) and 65+/-21 mL/m(2) (P<0.05), respectively, with captopril, and 58+/-18 versus 64+/-18 (P<0.05) and 69+/-30 mL/m(2) (P<0.05), respectively, with atenolol. Neither group showed significant changes in end-systolic volume. Among patients with perfusion defect >18% (n=51), those treated with atenolol showed a significant increase of end-systolic and end-diastolic ventricular volumes, whereas captopril-treated patients did not.

CONCLUSIONS

Although early treatment with atenolol or captopril results in similar overall short- and medium-term preservation of ventricular function and volumes, in patients with larger infarctions, a beta-blocker alone does not adequately protect myocardium from ventricular dilatation.

Reduction of exercise-induced myocardial ischemia during add-on treatment with the angiotensin-converting enzyme inhibitor enalapril in patients with normal left ventricular function and optimal beta blockade

OBJECTIVES

We sought to study the effect of angiotensin-converting enzyme inhibition on exercise-induced myocardial ischemia.

BACKGROUND

Although angiotensin-converting enzyme inhibitors have been shown to reduce ischemic events after myocardial infarction, few data are available regarding their direct anti-ischemic effects in patients with coronary artery disease.

METHODS

We studied 43 patients (average age 63 +/- 8 years) with exercise-induced myocardial ischemia (> or =0.1 mV ST depression, despite optimal beta blockade) and normal left ventricular function (ejection fraction >0.50). In a double-blind, placebo-controlled parallel design, patients were treated with angiotensin-converting enzyme inhibitor (enalapril 10 mg twice daily) or placebo. Assessments were made after three weeks (short-term) and 12 weeks (long-term).

RESULTS

At baseline, the groups were well matched for all clinical characteristics. After three weeks, there was a slight but not significant increase in time to 0.1 mV ST depression in both groups (p = NS); rate pressure product (RPP = heart rate x systolic blood pressure) was also unaffected. After 12 weeks, however, time to 0.1 mV ST depression further increased in the enalapril group (5.6 +/- 1.9 min) but was unchanged in the placebo group (4.4 +/- 1.3 min; p < 0.05 between groups). In contrast, RPP was not affected. Concentrations of both atrial and brain natriuretic peptides at peak exercise tended to be lower by enalapril, if compared to placebo (p = NS).

CONCLUSIONS

Angiotensin-converting enzyme inhibition may reduce exercise-induced myocardial ischemia in patients with normal left ventricular function. Further studies are needed to elucidate the mechanisms involved.

The endothelium: a gynecological and obstetric point of view

The endothelium, long considered merely an inert, semipermeable membrane between blood and the vessel wall, is now viewed as an important, large and highly active endocrine organ which is responsible for a number of vital physiological functions. In this editorial we will discuss the important role of the endothelium and endothelial (dys)function in health and disease, with particular focus on postmenopausal cardiovascular disease and preeclampsia.

Interaction between Aspirin and ACE Inhibitors in Patients with Heart Failure

Both aspirin (acetylsalicylic acid) and ACE inhibitors are often used concomitantly, especially in patients with both heart failure and ischaemic heart disease, which is the most common underlying cause of heart failure. The safety of the association has been questioned because both drugs affect a related prostaglandin-mediated pathway. Thanks to their vasodilating properties, prostaglandins play an important role in heart failure where peripheral vasoconstriction occurs. Some of the beneficial effects of ACE inhibitors might be related to reduced degradation of bradykinin that enhances the synthesis of prostaglandins, while aspirin, through inhibiting the enzyme cyclo-oxygenase, inhibits the production of prostaglandins. To date no prospective study has been conducted to investigate the effect of long term aspirin treatment in the postinfarction period allowing the possible impact of the interaction between aspirin and ACE inhibitors upon survival to be confirmed or negated. However, the practitioner needs to know how to optimise the treatment of his or her patients. In order to stimulate arguments for and against the use of aspirin in patients with heart failure receiving ACE inhibitors, we searched MEDLINE from 1960 to 2000 using the key words heart failure, aspirin, and ACE inhibitors for English language articles and conducted a review of the available data. We report on the potential mechanisms of the interaction and the results of experimental studies on haemodynamic parameters. Results of retrospective clinical studies, subgroup analysis that were undertaken to evaluate the overall action upon haemodynamic parameters and survival of the association are summarised. Conflicting conclusions have been reported in the literature. Many explanations can be advanced to try to understand these conflicting conclusions: differences in study design (results of retrospective trials have to be interpreted with caution); differences in the choice of the evaluation parameter (problem of the clinical relevance of haemodynamic parameters); differences in the characteristics of the patient (different underlying cardiopathy, e.g. heart failure, hypertension or ischaemic cardiopathy); and differences in the type and the dosage of each treatment (especially ACE inhibitors and aspirin since an interaction might occur more often with dosage of aspirin greater than 250mg).

What is the optimal medical management of ischaemic heart failure?

Ischaemic heart disease is probably the most important cause of heart failure. All patients with heart failure may benefit from treatment designed to retard progressive ventricular dysfunction and arrhythmias. Patients with heart failure due to ischaemic heart disease may also, theoretically, benefit from treatments designed to relieve ischaemia and prevent coronary occlusion and from revascularisation. However, there is little evidence to show that effective treatments, such as angiotensin converting enzyme (ACE) inhibitors and beta-blockers, exert different effects in patients with heart failure with or without coronary disease. Moreover, there is no evidence that treatment directed specifically at myocardial ischaemia, whether or not symptomatic, or coronary disease alters outcome in patients with heart failure. Some agents, such as aspirin, designed to reduce the risk of coronary occlusion appear ineffective or harmful in patients with heart failure. There is no evidence, yet, that revascularisation improves prognosis in patients with heart failure, even in patients who are demonstrated to have extensive myocardial hibernation. On current evidence, revascularisation should be reserved for the relief of angina. Large-scale, randomised controlled trials are currently underway investigating the role of specific treatments targeted at coronary syndromes in patients who have heart failure. The CHRISTMAS study is investigating the effects of carvedilol in a large cohort of patients with and without hibernating myocardium. The WATCH study is comparing the efficacy of aspirin, clopidogrel and warfarin. The HEART-UK study is assessing the effect of revascularisation on mortality in patients with heart failure and myocardial hibernation. Smaller scale studies are currently assessing the safety and efficacy of statin therapy in patients with heart failure. Only when the results of these and other studies are known will it be possible to come to firm conclusions about whether patients with heart failure and coronary disease should be treated differently from other patients with heart failure due to left ventricular systolic dysfunction.

No effects on myocardial ischaemia in patients with stable ischaemic heart disease after treatment with ramipril for 6 months

OBJECTIVE: To assess the effects of a 6-month angiotensin-converting enzyme (ACE) inhibitor intervention on myocardial ischaemia. METHOD: We randomized 389 patients with stable coronary artery disease to double-blind treatment with ramipril 5 mg/day (n = 133), ramipril 1.25 mg/day (n = 133), or placebo (n = 123). Forty-eight-hour ambulatory electrocardiography was performed at baseline, and after 1 and 6 months. RESULTS: Relevant baseline variables were similar in all groups. Changes over 6 months in duration of >/= 1 mm ST-segment depression (STD), total ischaemic burden and maximum STD did not differ significantly between the treatment groups. There was no difference in the frequency of adverse events between the groups. CONCLUSION: ACE inhibitor treatment has little impact on incidence and severity of myocardial ischaemia in patients with stable ischaemic heart disease.

Genetic background in patients with acute myocardial infarction

The renin-angiotensin system is believed to play important roles in the development of acute myocardial infarction, and gene polymorphisms may also be involved. To investigate the genetic background in patients with acute myocardial infarction, we performed a case control study in a Japanese population. The study included 150 patients with acute myocardial infarction and 150 healthy, age- and sex-matched controls. We examined polymorphisms of angiotensin II type 1 receptor (1 166 A / C), type 2 receptor (3123 C / A), and bradykinin B2 receptor (-58 T / C) in these subjects. The allelic frequencies of angiotensin II type I receptor C and angiotensin II type 2 receptor A were significantly higher in the acute myocardial infarction subjects than in the control subjects, and this tendency was more significant in the younger patients. The combined ratios of angiotensin II type 1 receptor C and type 2 receptor A alleles in patients under 64 years old were significantly higher than in their older counterparts. However the total numbers of conventional coronary risk factors (hypertension, hypercholesterolemia, diabetes mellitus, and smoking) in individual subjects were not significantly different between younger and older patients. These polymorphisms were found to be involved in the development of acute myocardial infarction, particularly in the younger patients, and it was concluded that the incidence of acute myocardial infarction might be reduced by management from the genotypes.

Antiatherosclerotic effects of ACE inhibitors: where are we now?

ACE inhibitors have been used extensively in the management of patients with hypertension and heart failure. Over the past decade, a large body of evidence has emerged indicating that ACE inhibition also favorably affects the vasculature, and that these effects are associated with improved patient outcomes. Such evidence is provided by several sources: (i) experimental studies, which demonstrate that in addition to blood pressure lowering, ACE inhibitors improve endothelial function and have a host of other beneficial effects on the arterial wall; (ii) epidemiologic studies, which link the renin-angiotensin-aldosterone system to increased risk for myocardial infarction, and (iii) clinical trials, which demonstrate that treatment with these agents reduces the risk for acute ischemic events, improves the function of the arterial endothelium and can retard the progression of the anatomic extent of atherosclerosis.

How long should angiotensin-converting enzyme inhibitors be given to patients following myocardial infarction: implications of the HOPE trial

Long-term treatment with angiotensin-converting enzyme inhibitors reduces post-infarction morbidity and mortality in patients with left ventricular (LV) systolic dysfunction or symptomatic heart failure. Until recently, the effect of such treatment in patients with preserved LV function has not been known. The results from the Heart Outcome Prevention Evaluation trial have indicated that long-term treatment with ramipril leads to a significant reduction in cardiovascular events in patients with atherosclerotic disease, including those with prior myocardial infarction and preserved LV function. These results suggest that long-term angiotensin-converting enzyme inhibition should also be considered in post-infarction patients with normal cardiac function.

Long-term effects of cholesterol lowering and angiotensin-converting enzyme inhibition on coronary atherosclerosis: The Simvastatin/Enalapril Coronary Atherosclerosis Trial (SCAT)

BACKGROUND

This long-term, multicenter, randomized, double-blind, placebo-controlled, 2 x 2 factorial, angiographic trial evaluated the effects of cholesterol lowering and angiotensin-converting enzyme inhibition on coronary atherosclerosis in normocholesterolemic patients.

METHODS AND RESULTS

There were a total of 460 patients: 230 received simvastatin and 230, a simvastatin placebo, and 229 received enalapril and 231, an enalapril placebo (some subjects received both drugs and some received a double placebo). Mean baseline measurements were as follows: cholesterol level, 5.20 mmol/L; triglyceride level, 1.82 mmol/L; HDL, 0.99 mmol/L; and LDL, 3.36 mmol/L. Average follow-up was 47.8 months. Changes in quantitative coronary angiographic measures between simvastatin and placebo, respectively, were as follows: mean diameters, -0.07 versus -0.14 mm (P:=0.004); minimum diameters, -0.09 versus -0.16 mm (P:=0. 0001); and percent diameter stenosis, 1.67% versus 3.83% (P:=0.0003). These benefits were not observed in patients on enalapril when compared with placebo. No additional benefits were seen in the group receiving both drugs. Simvastatin patients had less need for percutaneous transluminal coronary angioplasty (8 versus 21 events; P:=0.020), and fewer enalapril patients experienced the combined end point of death/myocardial infarction/stroke (16 versus 30; P:=0.043) than their respective placebo patients.

CONCLUSIONS

This trial extends the observation of the beneficial angiographic effects of lipid-lowering therapy to normocholesterolemic patients. The implications of the neutral angiographic effects of angiotensin-converting enzyme inhibition are uncertain, but they deserve further investigation in light of the positive clinical benefits suggested here and seen elsewhere.

Lack of association between the angiotensin-converting enzyme insertion/deletion polymorphism and plasminogen activator inhibitor-1 antigen levels in the National Heart, Lung, and Blood Institute Family Heart Study

Experimental and clinical research supports a direct link between activation of the renin-angiotensin system and production of plasminogen activator inhibitor-1 (PAI-1), the primary physiologic inhibitor of tissue plasminogen activator. Several studies have reported higher PAI-1 levels in individuals carrying the deletion (D) allele of the angiotensin-converting enzyme (ACE) gene. We investigated the association between ACE genotypes and plasma PAI-1 levels in a family study of 577 women and 428 men from four US communities. Participants were between 25 and 84 years of age without evidence of coronary heart disease (CHD). Mean geometric plasma PAI-1 levels adjusted for ethnicity were 17.4, 17.9, and 18.1 ng/ml in participants with the DD, insertion-deletion (ID), and II genotypes, respectively (P = 0.89 for difference). We found no associations between ACE I/D genotypes and plasma PAI-1 antigen concentrations in a subset of participants without major CHD risk factors (hypertension, hypercholesterolemia, overweight, smoking, diabetes) or in a small sample of African-Americans. Our findings suggest that the ACE insertion/deletion polymorphism has relatively little, if any, influence on circulating PAI-1 levels in the population at large.

Effects of angiotensin-converting enzyme inhibitor during warm blood cardioplegia

BACKGROUND

Effects of captopril, an angiotensin-converting enzyme inhibitor, during warm blood cardioplegia were assessed in the blood-perfused, isolated rat heart.

METHODS

The isolated hearts were arrested for 60 minutes with warm blood cardioplegia given at 20-minute intervals and were reperfused for 60 minutes. The control group (n = 10) received standard cardioplegia and the captopril group (n = 10) received cardioplegia supplemented with captopril (2 mmol/L). Cardiac function, myocardial metabolism, and cardiac release of circulating adhesion molecules were assessed before and after cardioplegic arrest.

RESULTS

Left ventricular end-diastolic pressure and -dp/dt were significantly (p<0.05) lower and coronary blood flow was significantly (p<0.05) greater in the captopril group than the control group during reperfusion. The captopril group resulted in significantly (p<0.05) less cardiac release of lactate, thiobarbituric acid reactive substances during reperfusion. Cardiac release of intercellular adhesion molecule-1 was significantly (p<0.05) less in the captopril group at 60 minutes of reperfusion.

CONCLUSIONS

The results suggest that supplementation of captopril during warm blood cardioplegia provides superior myocardial protection by suppressing lipid peroxidation and leukocyte-endothelial cell interaction during reperfusion.

The non-insulin-dependent diabetes, hypertension, microalbuminuria or proteinuria, cardiovascular events, and ramipril (DIABHYCAR) study: design, organization, and patient recruitment. DIABHYCAR Study Group

The non-insulin-dependent DIABetes, HYpertension, microalbuminuria or proteinuria, CARdiovascular events, and Ramipril (DIABHYCAR) study is a randomized, prospective, double-blind, placebo-controlled, multicenter international trial of the ACE inhibitor ramipril (1.25 mg/day) in patients with type II diabetes and micro- or macroalbuminuria. The main outcome of the study is the time to first occurrence of either death from a cardiovascular origin, including sudden death, nonfatal myocardial infarction, stroke, or congestive heart failure, or requirement of hemodialysis or renal transplantation. The study was launched in France in early 1995 with the participation of general practitioners only, but had to be extended to 15 other countries in 1997 due to difficulties in recruitment. Since 2.5 years after the beginning of the trial the observed event rate was much less than anticipated, it was decided to increase recruitment and follow-up duration and to include congestive heart failure in the definition of the main outcome to keep the study power at a satisfactory level. Recruitment ended on April 1, 1998 with 4937 randomized patients. Following the early discontinuation for efficacy of another study of ramipril in high cardiovascular risk patients, the Heart Outcomes Prevention Evaluation study (HOPE), the second interim analysis of DIABHYCAR was performed early (when 406 instead of 500 patients presented a main outcome) and the Data Safety and Monitoring Board recommended that the study continue. Follow-up is planned to end on March 31, 2001.

Effects of acute and chronic angiotensin receptor blockade on myocardial vascular blood volume and perfusion in a pig model of coronary microembolization

Based on the reduction of ischemic cardiac events in clinical trials and experimental observations, inhibition of the effects of angiotensin II on coronary microcirculatory function may afford myocardial protection after injury. The immediate effects of intracoronary AT1 receptor blockade with irbesartan were examined in a pig model in the healthy myocardium and in acute ischemia induced by injection of 30-microm microspheres into the left anterior descending coronary artery (LAD). Electron-beam computed tomography was performed for in-vivo quantitative measurements of regional intramyocardial vascular blood volume (V(B)) and perfusion (F(M)), as well as left ventricular ejection fraction (LVEF) and muscle mass. Ratios of V(B) and F(M) in the anterior (LAD-supplied)/ inferior (control) myocardium were generated. At baseline, 0.2 mg/kg irbesartan injected into the LAD increased V(B) and F(M) ratios significantly by 27 +/- 8% and 51 +/- 13%, respectively. After anterior coronary microembolization, V(B) and F(M) ratios were 0.60 +/- 0.05 and 0.51 +/- 0.05, respectively, and were significantly increased by irbesartan (by 24 +/- 10% and by 36 +/- 11%, respectively). After 4 weeks of treatment with oral irbesartan (n = 7) or placebo (n = 7), an improved LVEF (56 +/- 4% v 44 +/- 4%, P = .046) was observed in irbesartan-treated animals, but no difference in LV end-diastolic volumes or muscle mass. Resting V(B) (0.95 +/- 0.06 v 0.76 +/- 0.06; P = .047) and F(M) (0.84 +/- 0.05 v 0.64 +/- 0.04; P = .016) ratios were significantly greater in irbesartan-treated animals. Using adenosine, there was a trend for higher V(B) and F(M) ratios in irbesartan- v placebo-treated animals. Therefore, in a pig model of acute myocardial ischemia, AT1 receptor blockade by irbesartan induced microvascular vasodilation and, ostensibly, conveyed myocardial protection. Long-term treatment with irbesartan resulted in moderate enhancements of resting V(B) and F(M) compared with placebo, suggesting a role for coronary microcirculatory effects of chronic AT1 receptor blockade in preserving LVEF.

Percutaneous coronary intervention versus medical therapy for coronary heart disease

Medical therapy reduces myocardial infarction and death in patients with stable coronary heart disease (CHD). In contrast, there is little evidence available to evaluate the impact of percutaneous coronary intervention (PCI) on hard endpoints in such patients. Four randomized, controlled trials have compared PCI with medical therapy. These studies have demonstrated that PCI results in an improvement in angina and exercise tolerance compared with medical therapy, but they also suggest that medical therapy may be preferable to PCI with respect to the risk of cardiac events. Interpretation of these studies has been limited by small sample size, exclusion of high-risk subjects, no or reduced use of stents, lack of a cost- effectiveness evaluation, and absence of risk factor intervention (except for Atorvastatin versus Revascularization Treatment, which used aggressive low-density lipoprotein lowering with atorvastatin in the medical group only). The Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) trial will permit better definition of the role of PCI in the treatment of stable or recently stabilized patients with CHD.

Acute and chronic angiotensin-1 receptor antagonism reverses endothelial dysfunction in atherosclerosis

BACKGROUND

The renin-angiotensin system may contribute to atherogenesis through the promotion of endothelial dysfunction. The present study was performed to determine whether angiotensin-1 (AT(1)) receptor inhibition improves endothelial dysfunction.

METHODS AND RESULTS

In the femoral circulation of 19 patients with atherosclerosis and of 9 control subjects, we studied microvascular responses to reactive hyperemia, angiotensin II, acetylcholine, and sodium nitroprusside before and after the administration of intra-arterial losartan (10 mg). Femoral artery flow velocity was measured with a Doppler flow wire, and the femoral vascular resistance index (FVRI) was calculated as mean arterial pressure divided by flow velocity. Losartan induced a minor (5.9+/-2%, P=0. 02) reduction in FVRI and inhibited angiotensin II-mediated vasoconstriction in both patient groups (P<0.01). After the administration of losartan, acetylcholine-mediated vasodilation was augmented in patients (44+/-5% to 58+/-4% reduction in FVRI with infusion at a rate of 150 microgram/min, P<0.001) but not control subjects. Vasodilation during reactive hyperemia was also greater after AT(1) receptor inhibition (P=0.03) in patients, but the response to sodium nitroprusside remained unchanged. In a separate group of 31 patients with atherosclerosis, we investigated the effect of 8 weeks of oral losartan therapy on brachial artery flow-mediated vasodilation with the use of high-resolution ultrasound. Oral losartan therapy improved flow-mediated brachial artery dilation (1.4+/-0.9% to 3.2+/-0.8%, P=0.03) but had no effect on the nitroglycerin response. Serum nitrogen oxide levels increased from 21.6+/-1.7 to 26.7+/-2.4 micromol/L (P=0.008).

CONCLUSIONS

The results of the present study indicate that inhibition of the AT(1) receptor in patients with atherosclerosis reverses endothelial dysfunction by improving NO availability and therefore may have long-term therapeutic benefits.

The role of plaque rupture and thrombosis in coronary artery disease

Atherosclerosis and its thrombotic complications are the major cause of morbidity and mortality in the industrialized world. The progression of atherosclerotic plaques in the coronary circulation is dependent on several risk factors. It is now clear that plaque composition is a major determinant of the risk of subsequent plaque rupture and superimposed thrombosis. The vulnerability of plaques to rupture is further determined by extrinsic triggering factors. Following rupture, the fatty core of the plaque and its high content of tissue factor provide a powerful substrate for the activation of the coagulation cascade. Plaque rupture can be clinically silent or cause symptoms of ischaemia depending on thrombus burden and the degree of vessel occlusion. In addition, plaque rupture and subsequent healing is recognized to be a major cause of further rapid plaque progression. This review looks at the mechanisms underlying the development and progression of atherosclerotic plaques, factors leading to plaque rupture and subsequent thrombosis and their clinical consequences. Finally, we speculate on targets for future research.

The Angiotensin-converting Enzyme Inhibition Post Revascularization Study (APRES)

OBJECTIVE

This study was performed to assess the effect of treatment with ramipril on the incidence of cardiac events after invasive revascularization in patients with asymptomatic moderate left ventricular dysfunction.

BACKGROUND

In patients with angina pectoris and left ventricular dysfunction, both invasive revascularization and treatment with angiotensin-converting enzyme inhibitors reduce cardiac mortality and morbidity. Whether there is a benefit from combining the two treatment strategies has never been evaluated prospectively.

METHODS

After invasive revascularization, 159 patients with preoperative chronic stable angina pectoris, left ventricular ejection fraction between 0.30 and 0.50 and no clinical heart failure were randomly assigned to receive double-blind treatment with either ramipril or placebo and subsequently followed for a median of 33 months.

RESULTS

Ramipril reduced the incidence of the triple-composite end point of cardiac death, acute myocardial infarction or clinical heart failure (risk reduction 58%; 95% confidence interval 7% to 80%, p = 0.031). The incidence of the quadruple-composite end point of cardiac death, acute myocardial infarction, clinical heart failure or recurrent angina pectoris was not altered with ramipril. These findings were consistent across subgroups with respect to left ventricular ejection fraction below or above 0.40, and whether coronary artery bypass grafting or percutaneous transluminal coronary angioplasty was performed.

CONCLUSIONS

In patients with angina pectoris and asymptomatic moderate left ventricular dysfunction, long-term treatment with ramipril after invasive revascularization significantly reduced the incidence of the composite end point of cardiac death, acute myocardial infarction or clinical heart failure, indicating that the beneficial effects of angiotensin-converting enzyme inhibitor treatment may be extended to include treatment of this patient group.

The HOPE Study (Heart Outcomes Prevention Evaluation)

The Heart Outcomes Prevention Evaluation (HOPE) study was designed to test the hypotheses that two preventive intervention strategies, namely angiotensin-converting enzyme (ACE) inhibition or vitamin E, would improve morbidity and mortality in patients at high risk of cardiovascular events compared with placebo. This review addresses the ACE inhibitor (ACE-I) (ramipril) arm of the study, both on the trial population as a whole, and on the large diabetic subgroup. Patients were included in the study who were considered to be at high risk of future fatal or non-fatal cardiovascular events, by virtue of their age (>55 years), existing or previous cardiovascular disease, or diabetes. Diabetics had at least one other risk factor, either known vascular disease or other factors such as cigarette smoking, high cholesterol or hypertension. Ramipril or placebo was added to concomitant medication, which included, in a substantial proportion of patients, antihypertensive drugs (excluding ACE-I), lipid-lowering agents or aspirin. As a result, despite a history of hypertension in nearly 50% of patients, blood pressure (BP) at baseline was normal and the reduction in BP attributable to ramipril modest (a fall of 3-4 mmHg systolic BP and 1-2 mmHg diastolic). The trial was stopped early on the advice of the Data Monitoring Committee because of convincing evidence of the benefit of ramipril treatment on the combined primary endpoint of cardiovascular death, non-fatal myocardial infarct (MI) and non-fatal stroke (14% vs. 17.8% on ramipril and placebo, respectively; relative risk reduction 22%, p<0.001). This comprised a risk reduction of 32% for stroke, 20% for MI, 26% for cardiovascular death and 16% for all-cause mortality, as well as a reduction in the risk of several other endpoints including heart failure and revascularisation procedures. The results among the 3577 diabetic subjects were even more striking, with a reduction of 25% in the combined primary endpoint. This reduction in the combined endpoint and in particular the reduction in MI far exceeded that which would be expected from the modest fall in BP. Furthermore, a multiple regression analysis of the diabetic subgroup showed similar relative risk reductions even after allowing for the effects of the fall in BP. Possible explanations for the non BP-mediated benefits of ramipril include reduction of angiotensin II-induced intimal and vascular smooth muscle proliferation and possible plaque stabilisation. The HOPE study results show that it is both safe and beneficial to lower BP that is already within the 'normal' range, particularly in patients with known vascular risk factors. This should greatly extend the use of ACE-I to a wider group of patients - not only those with left ventricular dysfunction, hypertension or diabetic microalbuminuria, but to the sort of high-risk patients who are currently given prophylactic treatment with aspirin.

Angiotensin-converting enzyme inhibitors downregulate tissue factor synthesis in monocytes

Angiotensin-converting enzyme (ACE) inhibitors reduce the risk of recurrent myocardial infarction in patients with left ventricular dysfunction. Tissue factor (TF), the initiator of blood coagulation, plays a pivotal role in arterial thrombosis that occurs after atherosclerotic plaque fissuring. Because monocytes synthesize TF and contain several components of the renin-angiotensin system, we investigated the possibility that ACE inhibitors could modulate monocyte TF expression. Mononuclear leukocytes from healthy volunteers were incubated with endotoxin in the presence or absence of different ACE inhibitors. Captopril reduced TF expression in endotoxin-stimulated mononuclear leukocytes, as measured by a 1-stage clotting assay and ELISA analysis, by approximately 60%. The effect was dose-dependent and was attributable to ACE inhibition, given that other ACE inhibitors, such as idrapril or fosinopril, and losartan, an antagonist of the angiotensin II AT(1) receptor, caused a comparable reduction in TF activity. Reverse transcriptase-polymerase chain reaction indicated that endotoxin-mediated increased levels of TF mRNA were inhibited by ACE inhibitors. Moreover, endotoxin-induced nuclear factor-kappaB translocation to the promoter region of the gene encoding for TF was markedly inhibited by captopril. The finding that ACE inhibitors and angiotensin II AT(1) antagonists can potentially modulate TF expression by mononuclear cells has important biological and therapeutic implications for the evolution of thrombi. Our results suggest that the anti-ischemic effect of these drugs might be explained, at least in part, by their ability to reduce TF expression in monocytes.

Current concepts in secondary prevention after acute myocardial infarction

Acute myocardial infarction (MI) is the leading cause of death around the globe. Advances in the field of cardiology have identified several effective treatments that have lead to decrease in mortality from this cause over the past 3 decades. The purpose of this article is to review the existing literature in regards to secondary prevention after acute MI. A search of MEDLINE through August of 1999 was carried out to identify any available publications on secondary prevention after MI. Evidence on the use of both pharmacological and nonpharmacological interventions that was shown to be effective in improving morbidity and mortality was sought. Recommendations for the treatment of patients with acute MI are made based on existing evidence. Betablockers, aspirin and lipid-lowering agents for patients with low density lipoprotein-cholesterol > 130 mg% should be used for all patients following a MI. Angiotensin converting enzyme inhibitors are indicated for patients with congestive heart failure and/or reduced left ventricular ejection fraction and are likely protective in most patients. Calcium channel blockers (Verapamil and Diltiazem) are indicated as second-line therapy for patients who have contraindications or are intolerant to betablockers. The routine prophylactic use of antiarrhythmic drugs to suppress ventricular ectopic beats should be avoided. Recommendations regarding diet, smoking cessation and achievement of ideal body weight should be an integral part of patient management. Referral for outpatient rehabilitation should also be strongly encouraged. Finally, adequate control of blood pressure and diabetes cannot be overemphasized. Adherence to these goals in patients with acute MI will lead to better long-term outcomes and reduction in cardiac death, recurrent MI, stroke, and need for coronary revascularization.