A Textbook of Clinical Pharmacology and Therapeutics

198 ISCHAEMIC HEART DISEASE

lesions whose symptoms are not adequately controlled by
medical therapy alone. Several antiplatelet drugs are given at
the time of PCI, including oral aspirinandclopidogrel, and a
glycoprotein IIb/IIIa inhibitor given intravenously such as
abciximab,eptifibatideortirofiban(Chapter 30). Aspirin
is usually continued indefinitely and clopidogrelis usually
continued for at least one month following the procedure.

MANAGEMENT OF UNSTABLE CORONARY

DISEASE

ACUTE CORONARY SYNDROME

Acute coronary syndrome (ACS) is a blanket term used to
describe the consequences of coronary artery occlusion,
whether transient or permanent, partial or complete. These
different patterns of coronary occlusion give rise to the
different types of ACS, namely unstable angina (where no
detectable myocardial necrosis is present), non-ST-segment-
elevation myocardial infarction (NSTEMI) and ST-segment-
elevation myocardial infarction (STEMI, usually larger in
extent and fuller in thickness of myocardial wall affected than
NSTEMI). A flow chart for management of ACS is given in
Figure 29.3. Unstable angina and NSTEMI are a continuum of
disease, and usually only distinguishable by the presence of

a positive serum troponin test in NSTEMI (troponin now being

the gold standard serum marker of myocardial damage); their

management is similar and discussed further here. Management

of STEMI is discussed separately below. All patients with ACS

must stop smoking. This is more urgent than in other patients

with coronary artery disease, because of the acute pro-throm-

botic effect of smoking.

Patients with ACS require urgent antiplatelet therapy, in the

form of aspirinandclopidogrel(Chapter 30), plus antithrom-

botic therapy with heparin (nowadays most often low-

molecular-weight heparinadministered subcutaneously; see

Chapter 30). Data from the CURE trial suggest that combined

aspirinandclopidogreltreatment is better than aspirinalone,

and that this combination should be continued for several

months, and preferably for up to a year, following which aspirin

alone should be continued. This antiplatelet/antithrombotic

regime approximately halves the likelihood of myocardial

infarction, and is the most effective known treatment for improv-

ing outcome in pre-infarction syndromes. By contrast, GTN,

while very effective in relieving pain associated with unstable

angina, does not improve outcome. It is usually given as a con-

stant-rate intravenous infusion for this indication. Aβ-blocker is

prescribed if not contraindicated. If β-blockers are contraindi-

cated, a long-acting Ca^2 -antagonist is a useful alternative.

Diltiazemis often used as it does not cause reflex tachycardia

and is less negatively inotropic than verapamil.β-Blockers and

Ca^2 -antagonists are often prescribed together, but there is dis-

appointingly little evidence that their effects are synergistic or

even additive. Moreover, there is a theoretical risk of severe

bradycardia or of precipitation of heart failure if β-blockers

are co-administered with these negatively chronotropic and

inotropic drugs, especially so for verapamil; where concomi-

tantβ-blockade and calcium-channel blockade is desired, it

is probably safest to use a dihydropyridine calcium-channel

blocker (e.g. nifedipineoramlodipine) rather than verapamil

ordiltiazem.Nicorandilis now often added as well, but again

there is not much evidence of added benefit. Coronary angiogra-

phy is indicated in patients who are potentially suitable for PCI

or CABG, and should be considered as an emergency in patients

who fail to settle on medical therapy.

ST-ELEVATION-MYOCARDIAL INFARCTION

(STEMI)

ACUTE MANAGEMENT

Oxygen

This is given in the highest concentration available (unless

there is coincident pulmonary disease with carbon dioxide

retention) delivered by face mask (FiO 2 approximately 60%) or

by nasal prongs if a face mask is not tolerated.

Pain relief

This usually requires an intravenous opiate (morphineor

diamorphine; see Chapter 25) and concurrent treatment with

an anti-emetic (e.g. promethazineor metoclopramide; see

Chapter 34).

Aspirin 75 mg once daily

Statin therapy

Sublingual GTN as

required (tablets or

preferably spray

Beta blocker

(e.g. atenolol)

Dihydropyridine calcium

antagonist (e.g. amlodipine

or nifedipine) or long acting nitrate

(e.g. isosorbide mononitrate)

if intolerant of above

Consider nicorandil if above

incompletely effective, poorly

tolerated or contraindicated

SIGNIFICANT/REGULAR

SYMPTOMS

MINIMAL/INFREQUENT

SYMPTOMS

Diltiazem or verapamil if intolerant

to beta blocker

Figure 29.2:Drug therapy of stable angina.