100 QUESTIONS IN CARDIOLOGY

30 What is appropriate secondary prevention after

acute myocardial infarction?

Michael Schachter

At least half the patients who suffer an acute infarct will survive

at least one month, though 10–20% will die within the next year.

It is to be hoped and expected that more active early intervention

will bring about further improvements in short term survival.

There is therefore a large and growing number of patients where

there is a need to prevent further cardiovascular events and to

maintain and improve the quality of life.

Aspirin

Aspirin at low to medium doses (75–325mg daily) reduces

mortality, reinfarction and particularly stroke by 10–45% after

myocardial infarction. It has been estimated that there is about

one serious haemorrhage, gastrointestinal or intracerebral, for

every event prevented. At the moment there is no comparable

evidence for dipyridamole, ticlopidine or clopidogrel.

Beta blockers

There is overwhelming evidence for the beneficial effect of beta

blockers, both within the first few hours of myocardial infarction

and for up to three years afterwards. Reduction in mortality

ranges from 15 to 45%, almost all of it accounted for by fewer

instances of sudden death. All beta blockers appear equally

suitable, except those with partial agonist activity. The contraindi-

cations are controversial, but most would include asthma, severe

heart block and otherwise untreated heart failure, but patients

with poor left ventricular function benefit most. In asthmatic

patients, particularly, heart rate limiting calcium channel blockers

(verapamil or diltiazem) may be useful alternatives to beta

blockers in the absence of uncontrolled heart failure.

Lipid-lowering drugs

The large secondary prevention trials with simvastatin and prava-

statin (4S, CARE, LIPID) have demonstrated unequivocally the