Drugs For Secondary Prevention

All patients should receive aspirin and a ¡3-blocker for at least two years, unless contraindicated. The commonest contraindication to (3-blockade after MI is heart failure, although this should now be uncommon after a first MI. In such patients, an ACE inhibitor should replace p-blockade. All three of these drug groups have been shown to reduce the incidence of reinfarction by 20-25%, although their benefit has not been shown to be additive. In the 'SAVE' study,28 captopril 50 mg x 3/d or placebo was started 3-16 days after a myocardial infarction in 2231 patients without overt cardiac failure but with a left ventricular ejection fraction of < 40%. The captopril group had a lower incidence of recurrent myocardial infarction (133) and deaths (228) than the placebo group (170 and 275). Similar results have been achieved in several other trials of ACE inhibitors. An exception was the CONSENSUS-II study, which found no benefit from enalapril. (In this study, large and rapid falls in BP caused by i.v. enalaprilat probably precipitated cardiovascular events in some patients.) Whereas most studies have used echo or isotope scanning to assess cardiac function, the AIRE study showed a reduction in deaths (170 vs 222) in the active group, receiving ramipril 5 mg x 2/d, started 3-10 days after a myocardial infarction in 2006 patients with only clinical signs of heart failure.28 Indeed, in addition to these drugs, most patients should receive a statin, regardless of their plasma cholesterol level. Long-term benefit from LDL reduction after MI has been shown for high-dose simvastatin (20^0 mg/d) and pravastatin (40 mg/d). Patients with previous MI constituted one-third of the Heart Protection Study of 20 536 high-risk patients. Those randomly assigned to simvastatin 40 mg daily or placebo had a 12% reduction in all cause mortality, and 24% reduction in strokes and coronary heart disease.29

There is no place for routine antiarrhythmic prophylaxis, and long-term anticoagulation is similarly out of place, except when indicated by arrhythmias or poor left ventricular function.

28 SAVE = Survival and Ventricular Enlargement Trial; AIRE

= Acute Infarction Ramipril Efficacy study; CONSENSUS = Cooperative New Scandinavian Enalapril Survival Study. References: Rutherford J D et al 1994 Effects of captopril on ischemic events after myocardial infarction. Results of the Survival and Ventricular Enlargement trial. SAVE Investigators. Circulation 90:1731-1738. AIRE Study Investigators 1993 Effect of ramipril on mortality and morbidity of survivors of acute myocardial infarction with clinical evidence of heart failure. Lancet 342: 821-828. Swedberg K P et al 1992 Effects of the early administration of enalapril on mortality in patients with acute myocardial infarction. New England Journal of Medicine 327: 678-684.

Arterial hypertension

Clinical evaluation of antihypertensive drugs seeks to answer two types of question:

1. Whether long-term reduction of blood pressure benefits the patient by preventing complications and prolonging life; these studies take years, require enormous numbers of patients and are extremely costly.

2. Whether a drug is capable of effective, safe and comfortable control of blood pressure for about one year. There is now sufficient evidence of the benefit of reducing elevated blood pressure that regulatory authorities do not demand trials of the first kind for all new drugs. Shorter studies are therefore deemed sufficient to allow the introduction of a new drug. However, such trials may not reveal the long-term consequences of some metabolic effects, e.g. on blood glucose, which may adversely affect the risk of coronary heart disease. Placebo effects are prominent in these shorter trials and must be carefully controlled in trial design.

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