Is aspirin safe in heart failure? more data

Blood coagulation in patients with chronic heart failure: evidence for hypercoagulable state and potential for pharmacological intervention

Incidence data on thromboembolism in patients with heart failure (which may include stroke, peripheral embolism, pulmonary embolism) are limited but provide a general population range from 1-5 cases per 1000 each year, increasing with age to more than 30 cases per 1000 each year among people aged 75 years or older. However, the incidence of thromboembolism varied depending very much on what was being investigated in each of these studies. Data from subgroup analysis of the larger heart failure trials would seem to support this incidence data, although there is very little true epidemiological data and no randomised, controlled trial has been designed to specifically investigate thromboembolism in patients with heart failure. The pathophysiology of heart failure is complex. There are many well recognised factors which are associated with thrombosis in heart failure patients, such as vascular abnormalities, increased coagulability and impaired blood flow. In the past 50 years many studies have been performed to investigate if oral anticoagulation is of benefit for the prevention of thromboembolism in patients with heart failure. The use of warfarin therapy for heart failure patients has been a controversial subject. Warfarin does have a role to play in patients with myocardial infarction and those with atrial fibrillation. Furthermore, in patients with congestive heart failure secondary to coronary artery disease, warfarin reduces the occurrence of nonfatal myocardial infarction and, therefore, may reduce the chances of progression to heart failure. It has also been shown that warfarin reduces the risk of thromboembolic strokes in patients recovering from myocardial infarction. At present, there is a lack of randomised data, and the incidence of bleeding complications in patients with heart failure has caused a decrease in the use of oral anticoagulants for the prevention of thrombosis. This review summarises the incidence, potential mechanism and therapeutic approaches for management of thromboembolism in heart failure.

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.

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.

Thromboembolism in heart failure: who should be treated?

The risk of thromboembolic complications in patients with heart failure and/or chronic left-ventricular systolic dysfunction is increased. Nevertheless, anticoagulant therapy in these patients is still a subject of debate. Atrial fibrillation is the only prospectively evaluated, proven thromboembolic risk factor and patients with atrial fibrillation benefit from long term anticoagulant therapy. The significance of other proposed thromboembolic risk factors in heart failure and/or chronic left-ventricular dysfunction such as gender, cause of myocardial disease, severity of heart failure, left-ventricular ejection fraction, left-ventricular thrombus, left ventricular aneurysm and history of previous thromboembolic event is less clear. This article summarizes key studies, assesses the incidence of thromboembolism, evaluates risk factors and proposes guidelines for anticoagulation of patients with heart failure and/or left ventricular systolic dysfunction.

Heart failure due to ischaemic heart disease: epidemiology, pathophysiology and progression

Ischaemic heart disease is the most common underlying cause of heart failure in industrialised countries. Its manifestations are protean with myocardial infarction being only one important facet. The prognosis of patients with heart failure due to ischaemic heart disease also appears to be worse than that associated with many other aetiologies. The presence of ischaemic heart disease may influence both the efficacy and choice of treatment. Agents such as digoxin and amlodipine appear less effective in patients with ischaemic heart disease while ACE inhibitors and beta-blockers appear as or more effective in patients with ischaemic heart disease. Many have expressed an opinion about how coronary disease should be managed in the patient with heart failure supported by little or no evidence. There are major theoretical and practical concerns about the use of anti-coagulant, anti-platelet and statin therapy in patients with heart failure as well as major theoretical benefits. Only randomised controlled trials will resolve these issues. The same may be said of revascularisation. Fortunately trials addressing all these areas are under way. This should put the management of coronary disease in patients with heart failure on a firm evidence-based footing.

Antiplatelet and anticoagulant therapy in the prevention of thromboemboli in chronic heart failure

Thromboembolism is an important complication in patients with heart failure. Several recent clinical trials have established the efficacy of anticoagulant therapy in patients with heart failure and atrial fibrillation. There is renewed interest in examining the role of antiplatelet and anticoagulation therapy in patients with heart failure in sinus rhythm. There is a need to identify patients at risk for thromboembolism in heart failure. However, there are data to suggest that occult thromboembolic events may contribute to disease progression, ischemic events, and sudden cardiac death. This review summarizes the incidence, potential mechanism, and therapeutic approaches for management of thromboembolism in heart failure.