Beta-blockers and practical advice in stable angina
THE CONTEXT
Beta-blockers reduce myocardial oxygen demand, while activity advice and preventive nitrate use help patients manage stable angina.
Beta-blocker effects and selection
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Beta-blockers lower myocardial oxygen demand by reducing heart rate, blood pressure and myocardial contractility. They may provoke bronchospasm in patients with asthma.
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Non-selective beta-blockers may theoretically aggravate coronary vasospasm by blocking coronary artery beta-2 adrenoceptors.
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A once-daily cardioselective preparation is preferable; examples given are slow-release metoprolol at 50–200 mg daily or bisoprolol at 5–15 mg daily.
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Beta-blockers should not be withdrawn abruptly. Rebound effects can cause dangerous arrhythmias, worsening angina or myocardial infarction, collectively described as the beta-blocker withdrawal syndrome.
Advice for patients with stable angina
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Patients should avoid smoking and aim for an ideal body weight.
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Regular exercise up to, but not beyond, the point of chest discomfort is beneficial and may promote collateral vessels.
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Patients should avoid severe unaccustomed exertion and vigorous exercise after a heavy meal or in very cold weather.
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A sublingual nitrate can be taken before exertion expected to induce angina.
Reversible ischaemia on myocardial perfusion imaging
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The illustrated scan shows even resting uptake of technetium-labelled tetrofosmin but reduced uptake during stress, particularly in the anterior wall and apex, demonstrating reversible ischaemia.