Study note
MedicineCardiology

Thrombolysis precautions and anti-anginal treatment

THE CONTEXT
The target lists relative contraindications to thrombolytic therapy and describes nitrate, β-blocker and calcium-channel blocker use in unstable angina and myocardial infarction.

Listed relative contraindications to thrombolysis

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The supplied list includes active internal bleeding, previous subarachnoid or intracerebral haemorrhage, uncontrolled hypertension, surgery within 1 month, recent trauma including traumatic resuscitation, high probability of active peptic ulcer, and pregnancy.

Nitrates

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Sublingual glyceryl trinitrate, 300–500 μg, is a useful first-aid measure in unstable angina or threatened infarction.
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Intravenous nitrates help treat left ventricular failure and relieve recurrent or persistent ischaemic pain. Listed regimens are glyceryl trinitrate 0.6–1.2 mg/hour or isosorbide dinitrate 1–2 mg/hour.

β-blockers and calcium-channel blockers

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Intravenous β-blockade relieves pain, reduces arrhythmias and improves short-term mortality in patients presenting within 12 hours of symptom onset. Listed regimens include atenolol 5–10 mg or metoprolol 5–15 mg over 5 minutes.
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Avoid intravenous β-blockade with heart failure and pulmonary oedema, systolic blood pressure below 105 mmHg, or heart rate below 65/minute.
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Nifedipine or amlodipine may be added for persistent chest discomfort, but either may cause tachycardia when used alone. Verapamil and diltiazem can be used when β-blockade is contraindicated.
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Long-term oral β-blockade reduces mortality by approximately 25% among survivors of acute myocardial infarction, but this benefit is not seen with normal left ventricular function.
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Patients with left ventricular systolic dysfunction or heart failure alongside COPD or peripheral arterial disease appear to obtain similar secondary prevention benefits and should receive maintenance β-blockade unless poorly tolerated.
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Bradycardia, AV block, hypotension and asthma can prevent tolerance of β-blockade.
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