Update on the interaction between aspirin and angiotensin-converting enzyme inhibitors

Identification of patients at risk of ischemic events for long-term secondary prevention

PURPOSE

To review the identification of patients at risk of secondary ischemic events, discuss the therapies available for their medical management, and identify the role of the nurse practitioner (NP) in their primary and long-term care.

DATA SOURCES

ACC/AHA 2007 guidelines for the management of patients with unstable angina and non-ST-elevation myocardial infarction, ACC/AHA 2005 guidelines for the management of patients with peripheral arterial disease, AHA/ASA 2006 guidelines for patients with ischemic stroke, AHA/ACC 2006 guidelines update for patients with coronary and other atherosclerotic vascular disease, and selected clinical articles identified through PubMed.

CONCLUSIONS

Preventive therapy in patients with atherothrombotic vascular disease is critical for reducing the risk of recurrent events. Almost all patients with atherosclerotic disease will benefit from general lifestyle modifications, and most will also benefit from appropriate pharmacotherapies targeting dyslipidemia, diabetes, hypertension, and platelet function. However, evidence suggests that secondary prevention strategies may not be utilized effectively.

IMPLICATIONS FOR PRACTICE

Increased awareness and implementation of clinical practice guidelines can reduce the risk of recurrent atherothrombotic events. NPs in primary care settings or in long-term care facilities are well placed to determine whether patients are receiving appropriate preventive care and to implement improvements in their management.

The problem of polypharmacy in heart failure

Improvements in the medical therapy for chronic heart failure have led to a dramatic decrease in the morbidity and mortality of patients with heart failure over the past two decades. This improvement has been gained at the expense of an increasing number of potent drugs that heart failure patients have to take chronically. Because heart failure forms the end-stage of different cardiovascular diseases and their predisposing risk factors, patients need drug treatment not only for heart failure itself but also for related conditions. Even more, because most heart failure patients are elderly, a number of unrelated, noncardiovascular diseases become apparent, which further increase the number of pharmaceutical substances with which heart failure patients are treated. The resulting polypharmacy leads to problems including economic burden, patient compliance, and most importantly, partly unpredictable drug interactions. This article reviews the existing data concerning some of these problems, to provide an aid for choosing the appropriate drugs in heart failure patients and minimizing the patient's risk.

Aspirin under fire: aspirin use in the primary prevention of coronary heart disease

The issue of aspirin use in the primary prevention of cardiovascular disease is still debated because of conflicting opinions on risks versus benefits. Recently, a United States Food and Drug Administration (FDA) panel rejected the approval of aspirin in the setting of primary prevention in moderate-risk patients. However, the United States Preventive Services Task Force recommends that clinicians discuss aspirin therapy with patients at increased risk for having a future coronary event. During the past 15 years, many large randomized trials have specifically addressed this issue and helped shape the decisions of the FDA panel and the Preventive Services Task Force. These trials lend a handful of experiences and results, with no clear recommendations for antiplatelet therapy in the setting of primary prevention of coronary heart disease (CHD). Recently, trial results have been assimilated into practical tools for risk stratification to guide aspirin use in this setting. An overview and critical evaluation of the work performed thus far is provided in order to lend insight into the ongoing debate and, through use of the Framingham CHD risk prediction score sheets, to better equip practitioners faced with the decision of giving aspirin to "relatively" healthy individuals for CHD primary prevention.

Arterial hypertension and ischaemic stroke

OBJECTIVES

Arterial hypertension is, besides age, the number one risk factor for ischaemic stroke. Patients with arterial hypertension frequently present with additional coexisting vascular risk factors interacting in a complex way.

MATERIAL AND METHODS

This paper reviews the benefit of antihypertensive treatment, as well as different treatment options of arterial hypertension and their side-effects.

RESULTS

Patients with definite arterial hypertension, but also patients with so-called normal or high-normal blood pressure are at increased risk to develop stroke and other cardiovascular complications. Vascular remodelling of small and large vessels provoked by arterial hypertension is the initial step in the development of atherosclerosis and lipohyalinosis. Vascular remodelling can be improved or even normalized by antihypertensive treatment with angiotensin-converting-enzyme inhibitors and angiotensin-I-receptor antagonists showing the most convincing effects. Angiotensin-converting-enzyme inhibitors and angiotensin-I-receptor antagonists have the lowest rate of side-effects, however, economic restraints hinder their general application. Statins are needed to treat dyslipidaemia. They also lower blood pressure and have a synergistic effect with the above two antihypertensive components in lowering blood pressure. In hypertensive patients, risk of stroke and other cardiovascular complications is determined by the blood pressure level and the presence or absence of target organ damage and the interaction with other risk factors, such as cigarette smoking, dyslipidaemia, and diabetes. These high-risk patients should be treated even more aggressively than usual.

CONCLUSIONS

In the vast majority of patients and healthy individuals, target blood pressure should be as high as or below 120/80 mmHg to minimize the occurrence of stroke and other cardiovascular complications.

Comparative effects of aspirin with ACE inhibitor or angiotensin receptor blocker on myocardial infarction and vascular function

OBJECTIVES

We previously showed that an angiotensin-converting enzyme inhibitor (captopril) or an angiotensin receptor blocker (losartan) reduced infarct size and improved endothelial function in a rat model of ischaemia-reperfusion. The present study was undertaken to see if aspirin (ASA) antagonised the beneficial effects of captopril or losartan.

METHODS

One hundred and fourteen Sprague-Dawley rats were randomised into six groups; Control, ASA, captopril, losartan, ASA+captopril, and ASA+losartan. ASA, captopril or losartan were given at a concentration of 40 mg/kg/day in drinking water. After six weeks of pre-treatment, the rats were subjected to 17 minutes of left anterior descending coronary artery occlusion and 120 minutes of reperfusion, with haemodynamic and ECG monitoring. During the reperfusion period, the effective refractory period (ERP), ventricular fibrillation threshold (VFT) and bleeding time (BT) were measured. In fresh aortic rings precontracted with phenylephrine, endothelium-dependent and -independent relaxations were assessed using acetylcholine and nitroglycerin.

RESULTS

Haemodynamic changes were not different between the groups. Serum ASA concentrations were 0.5, 1.1 and 0.6 mg/dl in the ASA, ASA+captopril and ASA+losartan groups, respectively, and BT was prolonged (p<0.01). ASA alone reduced endothelium-dependent relaxation (-29+8 vs. -69+11%, p<0.01), but did not change endothelium-independent relaxation. ASA did not affect endothelial relaxation induced by acetylcholine in the presence of either captopril or losartan. Angiotensin I and ERP were elevated by captopril and losartan. Angiotensin II and VFT were elevated by losartan. ASA with captopril, captopril and losartan equally reduced infarct size, compared with control (39+3, 39+4, and 39+5 vs. 53+3%, all p<0.05).

CONCLUSIONS

Captopril and losartan had similar cardiovascular protective effects in a rat model of ischaemia-reperfusion. Aspirin did not attenuate the cardiovascular protective effects of captopril or losartan.

Potential adverse interaction between aspirin and lisinopril in hypertensive rats

The potential clinical effect of aspirin (ASA) in patients treated with angiotensin converting enzyme (ACE) inhibitors is debatable. Several studies have suggested that ASA attenuates the beneficial effects of ACE inhibitors in hypertension, congestive heart failure (CHF) or coronary artery disease (CAD) and have questioned the safety of using ASA concomitantly with these agents. The present study aims to investigate the possible interaction between ASA and ACE inhibitor in hypertensive rats. Hypertension was induced in adult male Wistar rats using Methylprednisolone (MP) 20 mg/kg per week s.c. for 2 weeks. The systolic blood pressure (SBP) was measured by noninvasive BP technique. The effect of Lisinopril (LS) 15 mg/kg per day and that of combination of LS and ASA; 100 and 25 mg/kg per day p.o. was studied on hypertension induced by glucocorticoid. Concurrent ASA treatment with LS did not hinder the hypotensive effect of LS at either dose. However ASA 100 mg/kg per day caused mortality in animals and produced massive cardiac necrosis and renal damage as evident from histopathology. Treatment with ASA 25 mg/kg per day caused lower mortality with variable effects on cardiac and renal tissues. These results indicate that ASA attenuates the beneficial effects of ACE inhibitor on survival in hypertensive rats and this effect was more pronounced at higher dose of ASA.

Pharmacologic management of diabetic nephropathy

BACKGROUND

Diabetes mellitus and hypertension are leading causes of end stage renal disease in the United States. Drug therapy that focuses on tight glycemic control and blood pressure control reduces the progression of nephropathy and cardiovascular complications. Angiotensin-converting enzyme (ACE) inhibitors have been shown to reduce the progression of renal disease in patients with diabetes. The angiotensin II receptor blockers (ARBs) losartan and irbesartan have also been shown to reduce microalbuminuria compared with placebo. The nondihydropyridine calcium channel blockers (CCBs) verapamil and diltiazem have been shown to be as effective as an ACE inhibitor in reducing urinary albumin excretion.

OBJECTIVE

This paper reviews the pathophysiology and diagnosis of diabetic nephropathy and recent clinical trials assessing the most appropriate therapeutic options for delaying the progression of nephropathy in patients with diabetes.

METHODS

Primary and review articles that addressed the pathophysiology, diagnosis, and therapeutic options for attenuating the progression of diabetic nephropathy were retrieved through a MEDLINE search (January 1990 to August 2002) and the bibliographies of identified articles were reviewed. English-language sources were searched using the following search terms: diabetes mellitus, nephropathy, proteinuria, ACE inhibitors, and ARBs. Studies published in peer-reviewed journals that were determined to be methodologically sound, with appropriate statistical analysis of the results, were selected for inclusion in this review.

RESULTS

Patients with type 1 diabetes mellitus and evidence of nephropathy should be started on an ACE inhibitor unless contraindicated. The ARBs and ACE inhibitors are viable choices for patients with type 2 diabetes mellitus and evidence of proteinuria. Patients who experience adverse events such as dry cough with ACE inhibitors can be switched to ARBs. Clinical literature suggests that if monotherapy with an ACE inhibitor or ARB does not provide an adequate response, a nondihydropyridine CCB should be added to the regimen. Nondihydropyridine CCBs should also be considered when ACE inhibitors and ARBs are contraindicated.

CONCLUSIONS

ACE inhibitors and ARBs should be considered first-line therapy for patients with type 2 diabetes mellitus and nephropathy. The ACE inhibitors are still the drug of choice for patients with type 1 diabetes mellitus and evidence of incipient or overt nephropathy. If therapeutic goals are not achieved with an ACE inhibitor or ARB, then the addition of a nondihydropyridine CCB should be considered.

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

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

Polypharmacy of heart failure. Creating a rational pharmacotherapeutic protocol

In the management of chronic heart failure, polypharmacy is common, necessary, and often overlooked. The increasing costs of care, noncompliance, and frequent adverse drug interactions have led to diminishing benefits by simply adding additional drugs to the already complex regimen. This review outlines a rational pharmacotherapeutic protocol based on establishing overall therapeutic goals and confirming treatment targets, tailoring therapy to individual patients by balancing beneficial and adverse drug effects, and paying particular attention to patient education and other nonpharmacologic support.

Optimizing treatment for chronic congestive heart failure in children

Treatment strategies for chronic heart failure in children have generally been extrapolated from studies in adults with heart failure. This presentation reviews the existing knowledge and recommendations regarding the treatment of chronic heart failure in adults and the information that is available in children. Medications currently recommended for use in adults include diuretics, digoxin, angiotensin-converting enzyme inhibitors, and beta-blockers. These recommendations are based on results from large, randomized, multicenter trials. Anecdotal evidence suggests similar beneficial effects of these medications in children. The fact that the etiologies, pathophysiology, and physiologic consequences of heart failure in children often differ greatly from those in adults, however, justifies the development of prospective, randomized trials to evaluate these medications specifically in children. Findings from these types of studies will provide critical information for developing guidelines for the appropriate treatment of children with chronic heart failure.

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.

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.