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 as pirin and angiotensin-converting enzyme inhibitors in patients with chronic stable cardiovascular disease. The interaction is less obvious in the post infarction setting, possibly reflecting the fact that many patients stop th eir aspirin therapy within a few months of such an event. An interaction is biologically plausible, because there is considerable evidence that angiot ensin-converting enzyme inhibitors exert important effects through increasi ng the production of vasodilator prostaglandins, whereas aspirin blocks the ir production through inhibition of cyclooxygenase, even at low doses. Ther e is some evidence that low-dose aspirin may raise systolic and diastolic b lood pressure. There is also considerable evidence that aspirin may entirel y neutralize the clinical benefits of angiotensin-converting enzyme inhibit ors in patients with heart failure. In addition, aspirin may have an advers e effect on outcome in patients with heart failure that is independent of a ny interaction with angiotensin-converting enzyme inhibitors, possibly by b locking endogenous vasodilator prostaglandin production and enhancing the v asoconstrictor potential of endothelin. The evidence is not sufficient to j ustify advising long-term aspirin therapy for patients with cardiovascular disease in general, and for those with heart failure in particular. Thus, t he 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 bene fits 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there is an opportunity to randomize the patient into a study of antithrombotic strategies, then aspirin should be withdrawn or possibly substituted with a n anticoagulant or an antiplatelet agent that does not block cyclooxygenase . In contrast, there is fairly robust evidence for a benefit of both aspiri n and angiotensin-converting enzyme inhibitors during the first 5 weeks aft er a myocardial infarction, with little evidence of an interaction. The com bination of aspirin and angiotensin-converting enzyme inhibitors is warrant ed during this period, after which discontinuation or substitution of aspir in with another agent should be considered. Curr Opin Nephrol Hypertens 10: 62--631, (C) 2001 Lippincott Williams & Wilkins.