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

Treatment of obesity hypertension and diabetes syndrome

Obesity has been shown to be an independent risk factor for coronary heart disease. The insulin resistance associated with obesity contributes to the development of other cardiovascular risk factors, including dyslipidemia, hypertension, and type 2 diabetes. The coexistence of hypertension and diabetes increases the risk for macrovascular and microvascular complications, thus predisposing patients to cardiac death, congestive heart failure, coronary heart disease, cerebral and peripheral vascular diseases, nephropathy, and retinopathy. Body weight reduction increases insulin sensitivity and improves both blood glucose and blood pressure control. Metformin therapy also improves insulin sensitivity and has been associated with decreases in cardiovascular events in obese diabetic patients. Antihypertensive treatment in diabetics decreases cardiovascular mortality and slows the decline in glomerular function. However, pharmacological treatment should take into account the effects of the antihypertensive agents on insulin sensitivity and lipid profile. Diuretics and beta-blockers are reported to reduce insulin sensitivity and increase triglyceride levels, whereas calcium channel blockers are metabolically neutral and ACE inhibitors increase insulin sensitivity. For the high-risk hypertensive diabetic patients, ACE inhibition has proven to confer additional renal and vascular protection. Because hypertension and glycemic control are very important determinants of cardiovascular outcome in obese diabetic hypertensive patients, weight reduction, physical exercise, and a combination of antihypertensive and insulin sensitizers agents are strongly recommended to achieve target blood pressure and glucose levels.

The Heart Outcomes Prevention Evaluation study: angiotensin-converting enzyme inhibitors: are their benefits a class effect or do individual agents differ?

The Heart Outcomes Prevention Evaluation study was a landmark study employing the angiotensin-converting enzyme inhibitor ramipril in a patient population pre-destined for vascular events. This study found that a 10 mg dose of ramipril in comparison with placebo reduced the incidence of death, myocardial infarction, stroke, and death from cardiovascular causes by 22%. This improvement in outcome was viewed as a direct consequence of ramipril, although the fact that blood pressure was reduced with ramipril has cast some considerable doubt on this supposition. Whether the observed findings in this study are a 'class effect' for all angiotensin-converting enzyme inhibitors is unclear. To its credit, ramipril is the first angiotensin-converting enzyme inhibitor shown to prevent ischemic events in high-risk patients without discernible left ventricular dysfunction. Other similar trials are underway, which are studying similar populations to those included in this landmark study and should resolve the question of whether the cardioprotective effects of angiotensin-converting enzyme inhibitors are a 'class effect'.

Is there a place for combining angiotensin-converting enzyme inhibitors and angiotensin-receptor antagonists in the treatment of hypertension, renal disease or congestive heart failure?

Angiotensin-converting enzyme inhibitors and angiotensin II receptor subtype 1 antagonists have proven to be effective and well tolerated antihypertensive agents. They also exhibit unique cardioprotective and renoprotective properties in patients with comorbid conditions such as congestive heart failure and proteinuria or renal insufficiency. This benefit is observed most dramatically in diabetic persons. Although inconclusive, the results of a limited number of clinical trials support the notion that additive antihypertensive, cardioprotective, and renoprotective effects may be obtained with combined used of angiotensin-converting enzyme inhibitors and angiotensin II receptor subtype 1 antagonists in some patients. More studies are needed to confirm the findings of these preliminary studies, and to define more clearly those subsets of patients who might derive the greatest benefit from angiotensin-converting enzyme inhibitor-angiotensin II receptor subtype 1 antagonist combination therapy.

Advances in antihypertensive combination therapy: benefits of low-dose thiazide diuretics in conjunction with omapatrilat, a vasopeptidase inhibitor

The preferred initial agents for the treatment of high blood pressure are low-dose thiazide diuretics, beta blockers, calcium antagonists, and angiotensin-converting enzyme (ACE) inhibitors. In high-risk patients, including those with diabetes, renal insufficiency, left ventricular dysfunction, and atherosclerosis, ACE inhibitors may have specific benefit in reducing cardiovascular morbidity and mortality. Omapatrilat, the prototypical vasopeptidase inhibitor, inhibits not only ACE but also neutral endopeptidase. Like conventional ACE inhibitors, omapatrilat causes extracellular volume reduction and vasodilatation; moreover, it increases levels of atrial and brain natriuretic peptides and bradykinin. Effective blood pressure control, especially in the high-risk patient, usually necessitates combination therapy. A recent study randomized 274 subjects with mild to severe hypertension (stages 1-3 diastolic blood pressure elevation) and confirmed the benefits of omapatrilat combined with hydrochlorothiazide in patients not controlled on hydrochlorothiazide alone. The frequencies of adverse events, serious adverse events, and discontinuation attributed to adverse events were similar for omapatrilat and placebo. Furthermore, there were no clinically significant changes in serum creatinine, potassium, or other laboratory parameters. Adding omapatrilat to the background of hydrochlorothiazide treatment produced statistically significant additional reductions in trough diastolic and systolic blood pressures at weeks 4 and 8.

Congestive heart failure with preserved systolic function in a statewide sample of community hospitals

BACKGROUND

The importance of congestive heart failure (CHF) in patients with preserved left ventricular systolic function is increasingly recognized, but most studies have been conducted at a single, usually academic, medical center. The aim of this study was to determine the prognosis, readmission rate, and effect of ACE inhibitor therapy in a Medicare cohort with CHF and preserved systolic function.

METHODS AND RESULTS

We examined a statewide, random sample of 1,720 California Medicare patients hospitalized with an ICD-9 diagnosis of CHF confirmed by a decreased left ventricular ejection fraction (EF) or chest radiograph from July 1993 to June 1994 and January 1996 to June 1996. Among the 782 patients with confirmed CHF and an in-hospital left ventricular EF measurement, 45% had reduced systolic function (ReSF) (EF < 40%) and 55% had preserved systolic function (PrSF) (EF > 40%). The PrSF group had a lower 1-year mortality rate but similar hospital readmission rates for both CHF and all causes. In patients with ReSF, ACE inhibitor treatment was associated with a lower mortality rate (P =.04) and a trend toward a lower CHF readmission rate (P =.13). In contrast, ACE inhibition therapy was associated with neither a lower rate of mortality nor CHF readmission in PrSF patients (P =.61 and.12, respectively). In multivariate analyses treatment with ACE inhibitors in PrSF patients was not associated with either a reduction in mortality (hazard ratio, 1.15; 95% CI, 0.79-1.67) or CHF readmission (hazard ratio, 1.21; 95% CI, 0.92-1.58).

CONCLUSIONS

CHF with PrSF seems to be associated with high mortality and morbidity rates, but ACE inhibitors may not produce comparable benefit in this group as in patients with ReSF.

Blood pressure control and benefits of antihypertensive therapy: does it make a difference which agents we use?

This article debates the important question of whether blood pressure lowering alone is responsible for the benefits accrued from antihypertensive therapy as demonstrated in many multicenter randomized clinical trials with different antihypertensive agents or whether there is evidence that some agents have special properties that result in benefits that go beyond those resulting from lowering blood pressure. Over the past >/=30 years, it has been demonstrated beyond any doubt that lowering blood pressure in severe forms of hypertension, and more recently in systolic and even mild hypertension, will result in reduced incidence of stroke and slower progression of heart and renal failure. These effects have been easier to demonstrate in sicker patients, because enough end points may be counted in the 3 to 5 years that these clinical trials last. However, risk attributable to high blood pressure comes, to a greater degree, from the much larger group of hypertensive individuals who have less severe forms of hypertension. Blood pressure lowering offers less protection from coronary heart disease, which is highly prevalent in hypertensive patients, than from stroke. With the introduction of agents such as renin-angiotensin system inhibitors or calcium channel blockers, it has been demonstrated that hypertensive vascular remodeling and endothelial dysfunction may be corrected. It has therefore been suggested that benefits beyond blood pressure lowering may be achieved with the use of specific drugs to lower blood pressure. Although some evidence suggests that this may be the case, it is difficult to extrapolate from mechanistic studies to prevention of hard end points in outcome trials and vice versa. The question remains for the time being largely unanswered.

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.

Blood pressure and inflammation in apparently healthy men

Inflammation plays an important role in the development of atherosclerosis, but the specific stimuli governing cytokine release in atherogenesis are unknown. We examined the hypothesis that hypertension may increase the risk of atherosclerosis via proinflammatory effects. In a cross-sectional study involving 508 apparently healthy men, we studied the association between blood pressure and baseline plasma concentrations of 2 inflammatory markers, intercellular adhesion molecule-1 (sICAM-1) and interleukin-6 (IL-6). Increase in systolic blood pressure (SBP) (P=0.003), pulse pressure (PP) (P=0.019), and mean arterial pressure (P=0.014) was significantly associated with levels of sICAM-1. All of these measures of blood pressure, as well as diastolic blood pressure (DBP), were significantly associated with levels of IL-6 (all, P</=0.001). In multiple linear regression models controlled for age and other cardiac risk factors, SBP (7.6 ng/mL per 10 mm Hg, P=0.016) and PP (8.13 ng/mL per 10 mm Hg, P=0.038) were significantly associated with sICAM-1 levels, whereas SBP (0.11 pg/mL per 10 mm Hg, P<0.001), DBP (0.11 pg/mL per 10 mm Hg, P=0.008), PP (0.10 pg/mL per 10 mm Hg, P=0.009), and mean arterial pressure (0.15 pg/mL per 10 mm Hg, P<0.001) had similar strong relationships with log-transformed IL-6 levels. Therefore, in apparently healthy men, we observed significant graded relationships between blood pressure and levels of sICAM-1 as well as IL-6. These data suggest that increased blood pressure may be a stimulus for inflammation and that this is a possible mechanism underlying the well-established role of hypertension as a risk factor for atherosclerotic disease.

Angiotensin-converting enzyme inhibition is associated with reduced troponin release in non-ST-elevation acute coronary syndromes

OBJECTIVES

This study was done to determine the effects of angiotensin-converting enzyme (ACE) inhibition and other clinical factors on troponin release in non-ST-elevation acute coronary syndrome (ACS).

BACKGROUND

Troponin is now widely used as a marker of risk in ACS, but determinants of its release have not been defined.

METHODS

This was a prospective cohort study of 301 consecutive patients admitted with non-ST-elevation ACS. Baseline clinical data were recorded, ACE gene polymorphism was determined and serial blood samples were obtained for troponin-I assay.

RESULTS

Significant troponin-I release (>0.1 microg/l) was detected in 93 (31%) patients. Pretreatment with ACE inhibitors, recorded in 53 patients (17.6%), independently reduced the odds of troponin-I release (odds ratio 0.25; 95% confidence intervals 0.10 to 0.64) and was associated with lower maximum troponin-I concentrations (median [interquartile range]) compared with patients not pretreated with ACE inhibitors (0.44 microg/l [0.19 to 2.65 microg/l] vs. 4.18 microg/l [0.91 to 12.41 microg/l], p = 0.01). Pretreatment with aspirin, recorded in 173 patients (57.5%), did not significantly reduce the odds of troponin-I release after adjustment but was associated with lower maximum troponin-I concentrations compared with patients not pretreated with aspirin (2.31 microg/l [0.72 to 8.02 microg/l] vs. 5.85 microg/l [1.19 to 12.79 microg/l], p = 0.05). The ACE genotyping (n = 268) showed 81 patients (30%) DD homozygous and 77 (29%) II homozygous. There was no association between ACE genotype and troponin release.

CONCLUSIONS

We conclude that ACE inhibition reduces troponin release in non-ST-elevation ACS. This is likely to be mediated by the beneficial effects of treatment on vascular reactivity and the coagulation system.

Arterial wave reflections and survival in end-stage renal failure

The increased effect of arterial wave reflections on central arteries like the common carotid artery seen in end-stage renal failure (ESRF) patients favors myocardial hypertrophy and oxygen consumption and alters coronary blood flow distribution. Nevertheless, the impact of wave reflection on the outcome and end points such as mortality remains to be demonstrated. One hundred eighty ESRF patients (age, 54+/-16 years) were monitored for 52+/-36 months (mean+/-SD). Seventy deaths, including 40 cardiovascular (CV) and 30 non-CV events, occurred. At entry, patients, in addition to standard clinical and biochemical analyses, underwent aortic pulse wave velocity measurement and determination of arterial wave reflexion by applanation tonometry on the common carotid artery that was expressed as augmentation index. Cox analyses demonstrated that predictors of all-cause and CV mortality were age, aortic pulse wave velocity, low diastolic blood pressure, preexisting CV disease, and increased augmentation index, whereas the prescription of an ACE inhibitor had a favorable effect on survival. After adjustment for all confounding factors, the risk ratio for each 10% increase in augmentation index was 1.51 (95% confidence interval, 1.23 to 1.86; P<0.0001) for all-cause mortality and 1.48 (95% confidence interval, 1.16 to 1.90; P<0.0001) for CV mortality. These results provide the first direct evidence that in ESRF patients increased effect of arterial wave reflections is an independent predictor of all-cause and CV mortality.

Pharmacotherapy in congestive heart failure. Prematurely terminated clinical trials and their application to cardiovascular medicine

Controlled clinical trials in cardiovascular disease remain the cornerstone of field-specific therapeutic advances. Since the introduction of the concept of controlled clinical trials, there has been considerable fine-tuning of the design, conduct, and analysis of such studies. A growing awareness of ethical issues emerging from such trials has led to increased public and investigator scrutiny and the routine requirement for both interim data analysis and full conflict-of-interest disclosure. A benefit of such interim analyses is that either an entire clinical trial or a specific treatment limb can be stopped if the observed findings warrant early termination. For example, highly positive findings, as were noted in the HOPE Study (Heart Outcomes Prevention Evaluation), led to its closure after 4.5 years of treatment, which was 1 year earlier than anticipated. Also, the doxazosin treatment limb of ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial) and the amlodipine treatment limb of AASK (African American Study of Kidney Disease and Hypertension) were stopped early, because of negative findings in one of their treatment limbs. Finally, economic considerations can enter into the decision to close a study early, as was the case in the CONVINCE (Controlled-Onset Verapamil Investigation of Cardiovascular Endpoints) trial. Most such decisions rely heavily on information obtained from independent data and safety monitoring boards. Such boards ensure patient safety by providing an unbiased, ongoing review of data, which would otherwise be unavailable until a study's completion. Early termination of a clinical trial can have important clinical and economic implications and, in particular, can substantially redirect the pattern of clinical practice. (c)2001 CHF, Inc.

Mediators of chronic heart failure: how drugs work

OBJECTIVE

To critically review the pathophysiology of chronic heart failure at the neurohormonal level, and discuss the effect of present and future therapeutic options on these neurohormones.

DATA SOURCES

A MEDLINE search (1986-November 2000) was used to identify important primary literature and reviews. Additional references were obtained from these articles.

DATA SYNTHESIS

Chronic heart failure is a common, progressive disorder with high morbidity and mortality. Progression is due in large part to several redundant neurohormonal responses. The neurohormones include angiotensin II, norepinephrine, aldosterone, endothelin-1, arginine vasopressin, and tumor necrosis factor. These responses are initially adaptive, but become maladaptive in the long term, impairing the function of the heart, vasculature, and kidneys. Counter-regulatory hormones, such as bradykinin and natriuretic peptides, are insufficient to offset the adverse effects of the other neurohormones. Most drugs used to treat chronic heart failure, such as angiotensin-converting enzyme inhibitors, beta-adrenergic antagonists, and spironolactone, achieve their benefits through altering the neurohormonal pathways. New agents that affect more or different neurohormones may soon be available.

CONCLUSIONS

Multiple agents are required for treatment of chronic heart failure, as no single agent can counteract all of the various adverse pathways. The appropriate prescription and use of such inherently complex regimens require significant physician and patient education.

Therapeutic potential of angiotensin II receptor antagonists

The circulating renin-angiotensin system plays an important role in cardiovascular homeostasis. More importantly, the local tissue renin angiotensin plays a pivotal role in cell growth and remodelling of cardiomyocytes and on the peripheral arterial vasculature. In addition, the renin angiotensin system is related to apoptosis, control of baroreflex and autonomic responses, vascular remodelling and regulation of coagulation, inflammation and oxidation. The cardioprotective and vascular protective effects of the angiotensin receptive blockade appears to be related to selective blockade of the angiotensin II (A-II) Type I (AT(1)) receptors. However, there is now growing evidence showing that some of the effects of AT-II receptor blockers (ARBs) are related to the activation of the kinin pathways. This paper will review some of the recent mechanisms related to the cardiovascular effects of angiotensin and more specifically of ARBs. This paper will present the novel data on the role of ARB in the development of atherosclerosis, vascular remodelling, coagulation balance and autonomic regulation. Finally, the role of ARBs, used alone or in combination with ACE inhibitor in patients with heart failure, will be discussed.

Effects of antihypertensive drugs on vascular remodeling: do they predict outcome in response to antihypertensive therapy?

Remodeling of large and small arteries in hypertension contributes to elevation of blood pressure, and may participate in the complications of hypertension. Large arteries exhibit increased lumen size, thickened media with increased collagen deposition, and decreased compliance, which contributes to raised systolic blood pressure and pulse pressure. In small (resistance) arteries smooth muscle cells are restructured around a smaller lumen, without true hypertrophy, particularly in milder forms of hypertension, whereas in severe forms and in secondary hypertension hypertrophic remodeling has been reported. Endothelial dysfunction occurs in many patients, with prevalence similar to that of left ventricular hypertrophy. Treatment with angiotensin-converting enzyme inhibitors, angiotensin receptor subtype 1 antagonists and long-acting calcium channel blockers has corrected changes in large and small arteries in hypertensive patients. Treatment with beta-blockers did not modify either structure or function of small arteries. Improved outcomes were reported in clinical trials with drugs that exert vascular protective effects, such as angiotensin-converting enzyme inhibitors and angiotensin receptor subtype 1 antagonists, as well as with those that do not appear to improve vascular structure or function. Recent trials suggest that these different drugs may provide similar benefits essentially through blood pressure lowering, although some minor differences between drugs have been noted. For example, the alpha-blocker doxasozin has been associated with worse outcomes (heart failure) than have diuretics. That hard end-point clinical trials have not demonstrated any advantages of agents with vasculoprotective properties may relate in part to the relatively short duration of some of these multicenter trials (3-5 years). Another contributing factor may be the low number of events with each drug class in the longer trials. Thus, current evidence does not support the rational expectation that vasculoprotective antihypertensive agents will be associated with better outcomes in hypertensive patients, possibly because of limitations of these trials.

Cardioprotective effects of ramipril and losartan in right ventricular pressure overload in the rabbit: importance of kinins and influence on angiotensin II type 1 receptor signaling pathway

BACKGROUND

The role of kinins in the cardioprotective effects of ACE inhibitors remains controversial.

METHODS AND RESULTS

Right ventricular pressure overload in rabbits was produced by pulmonary artery banding for 21 days. Rabbits were untreated, or they received the ACE inhibitor ramipril with or without bradykinin B(1) and B(2) receptor blockers or the angiotensin (Ang) II type I (AT(1)) receptor blocker losartan. Pulmonary artery banding caused right ventricular hypertrophy, depressed papillary muscle contractility, and loss of Ang II contractile effects because of a signaling defect downstream of AT(1) receptors. Paradoxically, AT(1) receptor density and G protein alpha subunits alphaq and alphai1/2 increased. Inotropic responsiveness to the alpha-receptor agonist phenylephrine was normal. Ramipril preserved cardiac contractility, but this effect was attenuated by simultaneous use of kinin receptor blockers. Ramipril also maintained responsiveness to Ang II and prevented AT(1) receptor and G protein upregulation. The simultaneous use of a kinin receptor blocker attenuated but did not prevent upregulation in the AT(1) receptor and G protein. Losartan had no effect on baseline contractility, but it maintained cardiac inotropic responsiveness to Ang II, prevented upregulation of AT(1) receptors, but did not modify G protein upregulation.

CONCLUSIONS

Pressure overload of the right ventricle decreases contractility, uncouples AT(1) receptors to downstream signaling pathways, and changes the expression of components of the AT(1) receptor signaling pathway. Ramipril attenuates these effects via kinins. Interventions that prevent local increases in Ang II or block AT(1) receptors also prevent decreased responsiveness of the AT(1) receptor in this model.

Effects of clopidogrel in addition to aspirin in patients with acute coronary syndromes without ST-segment elevation

BACKGROUND

Despite current treatments, patients who have acute coronary syndromes without ST-segment elevation have high rates of major vascular events. We evaluated the efficacy and safety of the antiplatelet agent clopidogrel when given with aspirin in such patients.

METHODS

We randomly assigned 12,562 patients who had presented within 24 hours after the onset of symptoms to receive clopidogrel (300 mg immediately, followed by 75 mg once daily) (6259 patients) or placebo (6303 patients) in addition to aspirin for 3 to 12 months.

RESULTS

The first primary outcome--a composite of death from cardiovascular causes, nonfatal myocardial infarction, or stroke--occurred in 9.3 percent of the patients in the clopidogrel group and 11.4 percent of the patients in the placebo group (relative risk with clopidogrel as compared with placebo, 0.80; 95 percent confidence interval, 0.72 to 0.90; P<0.001). The second primary outcome--the first primary outcome or refractory ischemia--occurred in 16.5 percent of the patients in the clopidogrel group and 18.8 percent of the patients in the placebo group (relative risk, 0.86; 95 percent confidence interval, 0.79 to 0.94; P<0.001). The percentages of patients with in-hospital refractory or severe ischemia, heart failure, and revascularization procedures were also significantly lower with clopidogrel. There were significantly more patients with major bleeding in the clopidogrel group than in the placebo group (3.7 percent vs. 2.7 percent; relative risk, 1.38; P=0.001), but there were not significantly more patients with episodes of life-threatening bleeding (2.2 percent [corrected] vs. 1.8 percent; P=0.13) or hemorrhagic strokes (0.1 percent vs. 0.1 percent).

CONCLUSIONS

The antiplatelet agent clopidogrel has beneficial effects in patients with acute coronary syndromes without ST-segment elevation. However, the risk of major bleeding is increased among patients treated with clopidogrel.

Lessons learned from prematurely terminated clinical trials

Controlled clinical trials in cardiovascular disease are the cornerstone for therapeutic advances in this field of medicine. Since the introduction of the concept of controlled clinical trials, there has been substantial progress in the design, conduct, and analysis of such studies. A growing awareness of ethical issues emerging from such trials has led to increased public and investigator scrutiny, and the routine requirement for interim data analysis. A benefit of such interim analysis is that either an entire clinical trial or a specific treatment limb can be stopped if the observed findings warrant premature termination. For example, highly positive findings, as were noted in the Heart Outcomes Prevention Evaluation (HOPE) study, led to its closure about 1 year early after 4.5 years of treatment. Alternatively, the doxazosin treatment limb of the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) and the amlodipine treatment limb of the African-American Study of Kidney Disease and Hypertension (AASK) were stopped early because of negative findings. Finally, economic considerations can enter into the decision to close a study early as was the case in the Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) trial. Most such decisions rely heavily on information obtained from independent data and safety monitoring boards. Such boards ensure patient safety by providing an unbiased ongoing review of data, which would otherwise be unavailable until a study's completion. Early termination of a clinical trial can have important clinical implications and, in particular, can redirect patterns of clinical practice.

Efficacy and safety of a therapeutic interchange from high-dose calcium channel blockers to a fixed-dose combination of amlodipine/benazepril in patients with moderate-to-severe hypertension

BACKGROUND

Recent hypertension trials have demonstrated the importance of achieving goal blood pressures to reduce the risk of target organ damage. In patients with moderate to severe hypertension, the use of high-dose monotherapy and/or combinations of drugs are necessary to achieve these goals. Fixed-dose combination products may be useful in these patients by reducing the number of daily doses required to control blood pressure.

OBJECTIVE

The objective of the present study was to evaluate the efficacy and safety of a therapeutic interchange between high-dose calcium channel blocker therapy and a fixed-dose combination of amlodipine/ benazepril (Lotrel; Novartis Pharmaceuticals, USA) in patients with moderate to severe hypertension.

METHODS

A total of 75 patients were switched from amlodipine (n = 25), felodipine (n = 25), and nifedipine-GITS (n = 25) to amlodipine/benazepril. Twenty-eight of the 75 patients (37%) were taking either a beta-blocker or a diuretic in addition to the high-dose calcium channel blocker prior to the switch. Blood pressure control, side effects and the cost of the therapeutic interchange were evaluated in the year following the therapeutic interchange.

RESULTS

Sixty-six of the 75 (88%) patients were successfully switched with maintenance of blood pressure control and without the development of new dose-limiting side effects. Reasons for treatment failure after the therapeutic interchange included loss of blood pressure control in five patients and the development of new dose-limiting side effects in four patients. These side effects included cough in three patients and rash in one patient. After accounting for differences in drug acquisition cost and costs related to the switch (clinic and emergency room and laboratory tests), a cost savings of $16030 for all 75 patients was realised in the first year. The per patient-per year cost savings was $214.

CONCLUSIONS

Our data indicate that a therapeutic interchange from selected high-dose calcium channel blockers to a fixed-dose combination of amlodipine/ benazepril can be successfully accomplished in the majority of patients.

Protection against ischemia: a physiological function of the renin-angiotensin system

The renin-angiotensin system (RAS) is involved in a complex mechanism that serves to preserve the blood supply to organs so that they can maintain cellular function. Angiotensin II exerts this effect, independently of the blood pressure generated, through two time-related events: a fast opening of the reserve collateral circulation and a much slower response of new vessel formation or angiogenesis. This effect is observed in rats with ligation of the abdominal aorta and in gerbils with abrupt or progressive unilateral carotid artery ligation. Inhibition of the angiotensin-converting enzyme (ACE) or the angiotensin II receptor represses this effect, and it appears that it is mediated through a non-AT1 receptor site of angiotensin II. Many tumors, both benign and malignant, express renin and angiotensin. It seems that the stimulating action of angiotensin II on angiogenesis could also be involved in preserving the blood supply to tumor cells. Administration of converting enzyme inhibitors increases survival and decreases tumor size in tumor-bearing rats. These observations support the hypothesis that the RAS, directly or indirectly, is involved in situations in which the restoration of blood supply is critical for the viability of cells and that it is present not only in normal but also in pathological conditions such as tumors. In view of the ubiquitous presence of renins and angiotensins, it is also likely to be involved in other conditions, such as inflammation, arthritis, diabetic retinopathy, and retrolental fibroplasia, among others in which angiogenesis is prominent. In addition, angiotensin II could be involved, through the counterbalance of the AT1 and AT2 receptors, in the rarefaction of blood vessels as an etiologic component of essential hypertension.

Cross sectional study estimating prevalence of heart failure and left ventricular systolic dysfunction in community patients at risk

OBJECTIVE

To examine a general practice population to measure the prevalence of signs and symptoms of heart failure (SSHF) and left ventricular systolic dysfunction (LVSD).

DESIGN

Cross sectional screening study in three general practices followed by echocardiography.

SETTING AND PATIENTS

All patients ⩾ 50 years in two general practices and ⩾ 40 years in one general practice were screened by case record reviews and questionnaires (n = 2158), to identify subjects with some evidence of heart disease. Among these, subjects were sought who had SSHF (n = 115). Of 357 subjects with evidence of heart disease, 252 were eligible for examination, and 126 underwent further cardiological assessment, including 43 with SSHF.

MAIN OUTCOME MEASURES

Prevalence of SSHF as defined by a modified Boston index, LVSD defined as an indirectly measured left ventricular ejection fraction ⩽ 0.45, and numbers of subjects needing an echocardiogram to detect one case with LVSD.

RESULTS

SSHF afflicted 0.5% of quadragenarians and rose to 11.7% of octogenarians. Two thirds were handled in primary care only. At ⩾ 50 years of age 6.4% had SSHF, 2.9% had LVSD, and 1.9% (95% confidence interval 1.3% to 2.5%) had both. To detect one case with LVSD in primary care, 14 patients with evidence of heart disease without SSHF and 5.5 patients with SSHF had to be examined.

CONCLUSION

SSHF is extremely prevalent in the community, especially in primary care, but more than two thirds do not have LVSD. The number of subjects with some evidence of heart disease needing an echocardiogram to detect one case of LVSD is 14.

Medical therapy or coronary artery bypass graft surgery for chronic stable angina: an update using decision analysis

PURPOSE

Randomized trials comparing medical and surgical therapies for the treatment of chronic stable angina were completed in the early 1980s. Therapies developed since then have decreased mortality and myocardial infarction rates from coronary artery disease. Using decision analysis and incorporating current recommendations for treatment, we simulated a trial comparing coronary artery bypass graft surgery and medical therapy.

METHODS

A Markov decision analysis model was constructed to compare the 5-year and 10-year outcomes of a simulated trial of medical therapy versus bypass surgery for stable chronic angina. Baseline data were obtained from a meta-analysis of trials comparing the two treatments. Data on risk reduction from contemporary therapies were obtained from randomized trials and meta-analyses.

RESULTS

All subgroups experienced modest gains in survival with current therapies. At 5 years, the survival rate was 90% in the medical group (an absolute gain of 6%) and 94% in the surgical group (an absolute gain of 4%). Similar results were obtained for patients with triple-vessel disease. Among patients with a low ejection fraction, the 5-year survival rate was 85% for medical patients and 92% for surgical patients. Sensitivity analyses did not substantially affect the conclusions.

CONCLUSION

Advances in the treatment of chronic stable angina have improved the outcome both for patients treated initially with surgery and for those treated initially with medical therapy. The improvements were of similar magnitude in both groups, so the fundamental conclusions of the bypass trials are unchanged.

Endothelial function and coronary artery disease

The endothelium produces a number of vasodilator and vasoconstrictor substances that not only regulate vasomotor tone, but also the recruitment and activity of inflammatory cells and the propensity towards thrombosis. Endothelial vasomotor function is a convenient way to assess these other functions, and is related to the long-term risk of cardiovascular disease. Lipids (particularly low density lipoprotein cholesterol) and oxidant stress play a major role in impairing these functions, by reducing the bioavailability of nitric oxide and activating pro-inflammatory signalling pathways such as nuclear factor kappa B. Biomechanical forces on the endothelium, including low shear stress from disturbed blood flow, also activate the endothelium increasing vasomotor dysfunction and promoting inflammation by upregulating pro-atherogenic genes. In contrast, normal laminar shear stress promotes the expression of genes that may protect against atherosclerosis. The sub-cellular structure of endothelial cells includes caveolae that play an integral part in regulating the activity of endothelial nitric oxide synthase. Low density lipoprotein cholesterol and oxidant stress impair caveolae structure and function and adversely affect endothelial function. Lipid-independent pathways of endothelial cell activation are increasingly recognized, and may provide new therapeutic targets. Endothelial vasoconstrictors, such as endothelin, antagonize endothelium-derived vasodilators and contribute to endothelial dysfunction. Some but not all studies have linked certain genetic polymorphisms of the nitric oxide synthase enzyme to vascular disease and impaired endothelial function. Such genetic heterogeneity may nonetheless offer new insights into the variability of endothelial function.

The antiatherogenic effects of antihypertensive treatment: trials completed and ongoing

B-mode ultrasonography provides a reliable means of measuring carotid artery wall intima-media thickness. Because carotid intima-media thickness is correlated with blood pressure and is predictive of future cardiovascular events, it can be used as an endpoint in intervention trials. Inclusion of carotid bifurcation in the measurements appears necessary for inferences about atherosclerosis. Several intervention studies using antihypertensive agents have been completed and others are ongoing. Placebo-controlled studies have shown beneficial effects of calcium antagonists and beta-blockers, and contradictory responses with angiotensin converting enzyme inhibitors, but none of these studies have been performed in hypertensive patients. In hypertensive patients, three studies comparing different antihypertensive agents have been completed, with some evidence favoring calcium antagonists over diuretics. Two studies are ongoing, and should be completed and published soon.

Dermal neurovascular dysfunction in type 2 diabetes

OBJECTIVE

To review evidence for a relationship between dermal neurovascular dysfunction and other components of the metabolic syndrome of type 2 diabetes.

RESEARCH DESIGN AND METHODS

We review and present data supporting concepts relating dermal neurovascular function to prediabetes and the metabolic syndrome. Skin blood flow can be easily measured by laser Doppler techniques.

RESULTS

Heat and gravity have been shown to have specific neural, nitrergic, and independent mediators to regulate skin blood flow. We describe data showing that this new tool identifies dermal neurovascular dysfunction in the majority of type 2 diabetic patients. The defect in skin vasodilation is detectable before the development of diabetes and is partially correctable with insulin sensitizers. This defect is associated with C-fiber dysfunction (i.e., the dermal neurovascular unit) and coexists with variables of the insulin resistance syndrome. The defect most likely results from an imbalance among the endogenous vasodilator compound nitric oxide, the vasodilator neuropeptides substance P and calcitonin gene-related peptide, and the vasoconstrictors angiotensin II and endothelin. Hypertension per se increases skin vasodilation and does not impair the responses to gravity, which is opposite to that of diabetes, suggesting that the effects of diabetes override and counteract those of hypertension.

CONCLUSIONS

These observations suggest that dermal neurovascular function is largely regulated by peripheral C-fiber neurons and that dysregulation may be a component of the metabolic syndrome associated with type 2 diabetes.

Cross sectional study estimating prevalence of heart failure and left ventricular systolic dysfunction in community patients at risk

OBJECTIVE

To examine a general practice population to measure the prevalence of signs and symptoms of heart failure (SSHF) and left ventricular systolic dysfunction (LVSD).

DESIGN

Cross sectional screening study in three general practices followed by echocardiography.

SETTING AND PATIENTS

All patients >/= 50 years in two general practices and >/= 40 years in one general practice were screened by case record reviews and questionnaires (n = 2158), to identify subjects with some evidence of heart disease. Among these, subjects were sought who had SSHF (n = 115). Of 357 subjects with evidence of heart disease, 252 were eligible for examination, and 126 underwent further cardiological assessment, including 43 with SSHF.

MAIN OUTCOME MEASURES

Prevalence of SSHF as defined by a modified Boston index, LVSD defined as an indirectly measured left ventricular ejection fraction </= 0.45, and numbers of subjects needing an echocardiogram to detect one case with LVSD.

RESULTS

SSHF afflicted 0.5% of quadragenarians and rose to 11.7% of octogenarians. Two thirds were handled in primary care only. At >/= 50 years of age 6.4% had SSHF, 2.9% had LVSD, and 1.9% (95% confidence interval 1.3% to 2.5%) had both. To detect one case with LVSD in primary care, 14 patients with evidence of heart disease without SSHF and 5.5 patients with SSHF had to be examined.

CONCLUSION

SSHF is extremely prevalent in the community, especially in primary care, but more than two thirds do not have LVSD. The number of subjects with some evidence of heart disease needing an echocardiogram to detect one case of LVSD is 14.

Prospectively designed overviews of recent trials comparing antihypertensive regimens based on different drug classes

Randomized trials have provided clear evidence of the beneficial effects of many different blood pressure-lowering regimens compared with placebo. The comparative effects of antihypertensive regimens based on different drug classes are less well established. The Blood Pressure Lowering Treatment Trialists' Collaboration conducted a series of prospectively designed overviews of randomized trials that compared the effects of different drug classes on major cause-specific outcomes. These overviews found no differences between the effects of regimens based on angiotensin converting enzyme inhibitors and those based on diuretics or b-blockers. There was limited evidence of small differences between regimens based on calcium antagonists and those based on diuretics or beta-blockers. The overviews of regimens based on calcium antagonists compared with those based on angiotensin converting enzyme inhibitors recorded too few events to provide reliable findings. Over the next few years, the findings of ongoing trials and future cycles of overview analyses conducted by the Collaboration should substantially add to these data.

Metabolic and hemodynamic response of adipose tissue to angiotensin II

OBJECTIVE

Recent studies have revealed the presence of a local renin-angiotensin system in adipose tissue. To examine the possible role of this system in adipose tissue, we performed microdialysis studies on the effect of angiotensin II (Ang II) on blood flow and metabolism in abdominal subcutaneous adipose tissue (aSAT) and femoral subcutaneous adipose tissue (fSAT) in young healthy men.

RESEARCH METHODS AND PROCEDURES

Using the microdialysis technique, two different protocols were run perfusion with Ringer's solution + 50 mM ethanol with the subsequent addition of 125, 250, and 500 microg/liter Ang II (n = 8) and Ringers's solution + 50 mM ethanol with the subsequent addition of isoproterenol (1 microM) alone and in combination with 500 microg/liter Ang II (n = 6). Dialysate concentrations of ethanol, glycerol, glucose, and lactate were measured for estimating blood flow (ethanol dilution technique), lipolysis, and glycolysis, respectively.

RESULTS

Perfusion with Ang II resulted in a dose-dependent decrease in blood flow (fSAT > aSAT), lipolysis (fSAT > aSAT), and glucose uptake (fSAT = aSAT). Isoproterenol increased blood flow and lipolysis at both sites and those effects could be returned to baseline values by the addition of Ang II in aSAT but not fSAT.

DISCUSSION

In conclusion, our data indicate that in addition to its well-known vasoconstricting effect, Ang II inhibits lipolysis in adipose tissue, whereby femoral fat depots seem to be more sensitive to this effect than abdominal depots.

Risk stratification in non-ST segment elevation acute coronary syndromes with special focus on recent guidelines

Patients with unstable angina or non-ST segment elevation (non-Q-wave) myocardial infarction are a heterogeneous group with respect to their risk of developing clinically significant adverse events such as subsequent myocardial infarction and death. Recent guidelines promote risk stratification of these patients, targeting high-risk patients for maximal antithrombotic and antiischemic therapy and low-risk patients for early discharge. We reviewed current and future modalities for risk stratification of patients and the predictive value of these methods in context with available pharmacologic agents. Unfortunately, most of the data identifying a particular pharmacologic regimen as beneficial in high-risk patients are retrospectively derived from large trials. Until prospective studies that use markers to guide therapy are available, clinicians should be familiar with the use of these risk markers and their application to the role of a given management strategy, including pharmacologic therapy.

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.

Trends in acute coronary heart disease mortality, morbidity, and medical care from 1985 through 1997: the Minnesota heart survey

BACKGROUND

Coronary heart disease (CHD) mortality continued to decline from 1985 to 1997.

METHODS AND RESULTS

We tabulated CHD deaths (ICD-9 codes 410 through 414) in the Minneapolis/St Paul, Minnesota, area. For 1985, 1990, and 1995, trained nurses abstracted the hospital records of patients 30 to 74 years old with a discharge diagnosis of acute CHD (ICD-9 codes 410 or 411). Acute myocardial infarction (AMI) events were validated and followed for 3-year all-cause mortality. Between 1985 and 1997, age-adjusted CHD mortality rates in Minneapolis/St Paul fell 47% and 51% in men and women, respectively; the comparable declines in US whites were 34% and 29%. In-hospital mortality declined faster than out-of-hospital mortality. The rate of AMI (ICD-9 code 410) hospital discharges declined almost 20% between 1985 and 1995, whereas the discharge rate for unstable angina (ICD-9 code 411) increased substantially. The incidence of hospitalized definite AMI declined approximately 10%, whereas recurrence rates fell 20% to 30%. Three-year case fatality rates after hospitalized AMI decreased consistently by 31% and 41% in men and women, respectively. In-hospital administration of thrombolytic therapy, emergency angioplasty, ACE inhibitors, beta-blockers, heparin, and aspirin increased greatly.

CONCLUSIONS

Declining out-of-hospital death rates, declining incidence and recurrence of AMI in the population, and marked improvements in the survival of AMI patients all contributed to the 1985 to 1997 decline of CHD mortality in the Minneapolis/St Paul metropolitan area. The effects of early and late medical care seem to have had the greatest contribution to rates during this time period.

Medical management of peripheral arterial disease

Peripheral arterial disease affects approximately 8-10 million people in the United States. Approximately one-third to one-half of these individuals are symptomatic. The risk factors that contribute to peripheral arterial disease are similar to those associated with other forms of atherosclerosis, including diabetes mellitus, cigarette smoking, hypercholesterolemia, high blood pressure, and hyperhomocysteinemia. Of these, diabetes and cigarette smoking pose the greatest risk for developing peripheral arterial disease. The prognosis of patients with these risk factors is limited because of their greater risks for myocardial infarction, stroke, and cardiovascular death. Cardiovascular mortality correlates inversely with the ankle/brachial index, and the risk of death is greatest in those with the most severe peripheral arterial disease. Treatment regimens to reduce cardiovascular morbidity and mortality in patients with peripheral arterial disease should include risk factor modification and antiplatelet therapy. The cardinal symptoms of peripheral arterial disease include intermittent claudication and rest pain, with the latter being indicative of critical limb ischemia. Therapeutic strategies that focus on improving the patient's quality of life, reducing the severity of claudication, and improving limb viability include supervised exercise training, pharmacotherapy, and revascularization. Two drugs-pentoxifylline and cilostazol-currently are approved by the Food and Drug Administration for the treatment of patients with claudication. Meta-analyses have suggested that, compared with placebo, pentoxifylline improves maximal walking distance by approximately 20-25%. Cilostazol is a phosphodiesterase type 3 inhibitor. In clinical trials, cilostazol has consistently improved maximal walking distance as compared with placebo, with the range of improvement being approximately 40-60%. Drugs that are currently under investigation include propionyl-L-carnitine, vasodilator prostaglandins, L-arginine, and the angiogenic factors, vascular endothelial growth factor and basic fibroblast growth factors.