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

Post-hospitalization management of high-risk coronary patients

The major cause of morbidity and mortality associated with coronary atherosclerosis is plaque rupture, which often results in one of the acute coronary syndromes: unstable angina, non-Q-wave myocardial infarction (MI), or Q-wave MI. Plaque rupture may be attributable to the thickness of the overlying fibrous cap; thinner plaques are more likely to rupture. It appears that the presence of inflammation is a significant contributor to rupture. Acute-phase treatments are highly efficacious, but secondary prevention, often overlooked, also is life-saving. Diet, exercise, and medications are the interventions available for secondary prevention. Four classes of medications--aspirin, beta blockers, angiotensin-converting enzyme (ACE) inhibitors, and 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins)--are also used in this setting with a high degree of success in reducing mortality and morbidity. Numerous studies have demonstrated a 30-50% reduction in mortality with aspirin. The reduction in mortality achieved with beta blockers in studies of patients after myocardial infarction are 15-50%. ACE inhibitors significantly reduce the risk of death from myocardial infarction in patients with coronary artery disease with or without myocardial infarction. Statins are beneficial even in patients whose cholesterol level is low to normal. Patients who were discharged on a statin showed a 50% reduction in mortality over those who did not receive statin therapy independent of lipid level. C-reactive protein, a marker of inflammation, is predictive of mortality, as are age and ejection fraction. Statins may be anti-inflammatory in addition to their lipid-lowering effect. Secondary-prevention strategies such as case management, electronic discharge prompting, better communication between referring physicians and cardiologists, and patient education may also have positive effects on after-discharge morbidity and mortality.

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.

Cardiovascular risk in diabetes: a brief review

Cardiovascular disease (CVD) is the major cause of the morbidity and mortality associated with diabetes in the US. A 2- to 3-fold incidence of CVD occurs in both type 1 and type 2 diabetic individuals over that in age- and gender-matched non-diabetic persons. Recent encouraging data demonstrating a decline in CVD mortality in the general US population do not reflect such a decline in the diabetic population, particularly in women. Increased risk for CVD is related to duration of diabetes and hyperglycemia, as well as hypertension, dyslipidemia, insulin resistance, gender, coagulation abnormalities, and other factors. Health care providers need to advocate for an uncompromising, multi-component attack on all modifiable risk factors for CVD, including glucose control, in the person with diabetes mellitus. This review focuses on known modifiable risk factors for CVD associated with diabetes, potential targets for primary and secondary prevention.

The past, present and future of hypertension management: a potential role for AT(1)-receptor antagonists

The benefits of effective antihypertensive treatment were established at least 40 years ago, but despite the availability of more reliable and better-tolerated antihypertensive drugs, the control of blood pressure remains poor in most patients. Long-term antihypertensive efficacy requires treatment that combines reliable 24-hour reduction of blood pressure with good tolerability to facilitate patient compliance. Treatment should also protect against target-organ damage. As the majority of negative cardiovascular effects of angiotensin II are mediated through the angiotensin II type 1 (AT(1)) receptor, specific blockade of this receptor is a rational approach for achieving these ideals. Several AT(1)-receptor blockers have been developed that combine antihypertensive efficacy and placebo-like tolerability - the latter being unique in the history of antihypertensive therapy. In experimental animals these drugs prevent or reverse target organ damage in the heart, the vasculature and the kidney. Ongoing large-scale outcome studies are now underway to establish the benefits of AT(1)-receptor blockade beyond blood pressure control.

Estimation of contribution of changes in coronary care to improving survival, event rates, and coronary heart disease mortality across the WHO MONICA Project populations

BACKGROUND

The revolution in coronary care in the mid-1980s to mid-1990s corresponded with monitoring of coronary heart disease (CHD) in 31 populations of the WHO MONICA Project. We studied the impact of this revolution on coronary endpoints.

METHODS

Case fatality, coronary-event rates, and CHD mortality were monitored in men and women aged 35-64 years in two separate 3-4-year periods. In each period, we recorded percentage use of eight treatments: coronary-artery reperfusion before, thrombolytics during, and beta-blockers, antiplatelet drugs, and angiotensin-converting-enzyme (ACE) inhibitors before and during non-fatal myocardial infarction. Values were averaged to produce treatment scores. We correlated changes across populations, and regressed changes in coronary endpoints on changes in treatment scores.

FINDINGS

Treatment changes correlated positively with each other but inversely with change in coronary endpoints. By regression, for the common average treatment change of 20, case fatality fell by 19% (95% CI 12-26) in men and 16% (5-27) in women; coronary-event rates fell by 25% (16-35) and 23% (7-39); and CHD mortality rates fell by 42% (31-53) and 34% (17-50). The regression model explained an estimated 61% and 41% of variance for men and women in trends for case fatality, 52% and 30% for coronary-event rates, and 72% and 56% for CHD mortality.

INTERPRETATION

Changes in coronary care and secondary prevention were strongly linked with declining coronary endpoints. Scores and benefits followed a geographical east-to-west gradient. The apparent effects of the treatment might be exaggerated by other changes in economically successful populations, so their specificity needs further assessment.

Vitamin E supplementation and cardiovascular events in high-risk patients

BACKGROUND

Observational and experimental studies suggest that the amount of vitamin E ingested in food and in supplements is associated with a lower risk of coronary heart disease and atherosclerosis.

METHODS

We enrolled a total of 2545 women and 6996 men 55 years of age or older who were at high risk for cardiovascular events because they had cardiovascular disease or diabetes in addition to one other risk factor. These patients were randomly assigned according to a two-by-two factorial design to receive either 400 IU of vitamin E daily from natural sources or matching placebo and either an angiotensin-converting-enzyme inhibitor (ramipril) or matching placebo for a mean of 4.5 years (the results of the comparison of ramipril and placebo are reported in a companion article). The primary outcome was a composite of myocardial infarction, stroke, and death from cardiovascular causes. The secondary outcomes included unstable angina, congestive heart failure, revascularization or amputation, death from any cause, complications of diabetes, and cancer.

RESULTS

A total of 772 of the 4761 patients assigned to vitamin E (16.2 percent) and 739 of the 4780 assigned to placebo (15.5 percent) had a primary outcome event (relative risk, 1.05; 95 percent confidence interval, 0.95 to 1.16; P=0.33). There were no significant differences in the numbers of deaths from cardiovascular causes (342 of those assigned to vitamin E vs. 328 of those assigned to placebo; relative risk, 1.05; 95 percent confidence interval, 0.90 to 1.22), myocardial infarction (532 vs. 524; relative risk, 1.02; 95 percent confidence interval, 0.90 to 1.15), or stroke (209 vs. 180; relative risk, 1.17; 95 percent confidence interval, 0.95 to 1.42). There were also no significant differences in the incidence of secondary cardiovascular outcomes or in death from any cause. There were no significant adverse effects of vitamin E.

CONCLUSIONS

In patients at high risk for cardiovascular events, treatment with vitamin E for a mean of 4.5 years had no apparent effect on cardiovascular outcomes.

Debate: Does it matter how you lower blood pressure?

Whether it matters how pressure is lowered has been debated since antihypertensive drugs proved to prevent cardiovascular events. However, in clinical trials, while the stroke benefit predicted by a given difference in blood pressure was achieved, the results for myocardial infarction were roughly half that expected. This suggested that adverse drug effects of diuretics and beta-blockers might have detracted from their hypotensive effects. Trials with newer antihypertensive classes have revealed superior effects on outcomes associated with converting enzyme inhibitor use, and that alpha-blockers are less cardioprotective than diuretics. These studies establish that simple blood pressure reduction is an inadequate guide to therapy. The challenge now will be to determine the optimal therapy for each hypertensive patient.

Interventions for deliberately altering blood pressure in acute stroke

BACKGROUND

It is unclear whether hypertension should be treated after acute stroke, and some have hypothesised that blood pressure should be increased to improve cerebral perfusion.

OBJECTIVES

The objective of this review was to assess the effect of lowering or elevating blood pressure in people with acute stroke, and the effect of different vasoactive drugs on blood pressure in acute stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group trials register, the Ottawa Stroke Trials Registry (1994), Medline (from 1965), Embase (from 1981), ISI, and existing review articles. We contacted researchers in the field and pharmaceutical companies.

SELECTION CRITERIA

Randomised trials of interventions that aimed to alter blood pressure in patients within two weeks of acute ischaemic or haemorrhagic stroke.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied the inclusion criteria and assessed trial quality. Two reviewers extracted the data.

MAIN RESULTS

Three trials involving 133 people were included. The trials tested the following vasodilators: nimodipine (66 people), nicardipine (five people), captopril (three people) and clonidine (two people). Oral calcium channel blockers (nimodipine, nicardipine) reduced systolic blood pressure (weighted mean difference 10.9mmHg, 95% confidence interval 2.0 to 19.7), diastolic blood pressure (weighted mean difference 9.5mmHg, 95% confidence interval 4.0 to 15.1) and heart rate (weighted mean difference 4.7 beats per minute, 95% confidence interval 0.2 to 9.2) at 48 hours. The greatest fall in blood pressure over the first 24 hours was shown in patients given the highest dose of nimodipine. The relationship between change in blood pressure and clinical outcome was not clear. There was not enough information to assess the effect of drugs other than calcium channel blockers. No studies of interventions to raise blood pressure were found.

REVIEWER'S CONCLUSIONS

There is not enough evidence to evaluate the effect of altering blood pressure after acute stroke. Although oral calcium channel blockers appear to reduce blood pressure following acute stroke, the balance of benefit and risk remains unclear.

Implications of recent hypertension trials for the generalist physician: whom do we treat, and how?

The publication of the results of the Swedish Trial in Old Patients with Hypertension-2 (STOP-2) and the termination of the doxazocin arm of the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack (ALLHAT) study again raise the question of whether all antihypertensives deliver equal cardiovascular outcome benefits. Data from research on congestive heart failure and from the Heart Outcomes Prevention Evaluation (HOPE) trial illuminate the roles and possible mechanisms of humoral mediators of vascular damage, suggesting, first, that some antihypertensives (thiazides, beta-blockers, and angiotensin-converting enzyme inhibitors) can deliver more improvement in outcomes than other agents and, second, that decisions on whom to treat are best made based on risk appraisal, not merely pressures.

Why do antioxidants fail to provide clinical benefit?

The results of recent randomized trials to test the influence of antioxidants on coronary-event rates and prognosis in patients with coronary-artery disease were disappointing. In none of these studies did the use of vitamin E improve prognosis. In contrast, treatment of coronary-artery disease with angiotensin-converting-enzyme (ACE) inhibitors reduced coronary-event rates and improved prognosis. ACE inhibition prevents the formation of angiotensin II, which has been shown to be a potent stimulus of superoxide-producing enzymes in atherosclerosis. The findings suggest that inhibition of superoxide production at enzymatic levels, rather than symptomatic superoxide scavenging, may be the better choice of treatment.

Debate: Subgroup analyses in clinical trials: fun to look at - but don't believe them!

Analysis of subgroup results in a clinical trial is surprisingly unreliable, even in a large trial. This is the result of a combination of reduced statistical power, increased variance and the play of chance. Reliance on such analyses is likely to be more erroneous, and hence harmful, than application of the overall proportional (or relative) result in the whole trial to the estimate of absolute risk in that subgroup. Plausible explanations can usually be found for effects that are, in reality, simply due to the play of chance. When clinicians believe such subgroup analyses, there is a real danger of harm to the individual patient.

Angiotensin receptor blockers in heart failure after the ELITE II trial

Specific blockers of the angiotensin type1 receptor, angiotensin receptor blockers (ARBs), have been introduced as an alternative to angiotensin-converting enzyme inhibitors (ACEi) for the treatment of heart failure. In comparison with ACEi, ARBs are better tolerated and have similar effects on haemodynamics, neurohormones and exercise capacity. Early studies have suggested that ARBs might have a superior effect on mortality. However, the first outcome trial, ELITE II (Losartan Heart Failure Survival Study), did not show any significant difference between losartan and captopril in terms of mortality or morbidity. This commentary outlines the role of ARBs in the treatment of heart failure.