Acute coronary syndrome (ACS) includes unstable angina, evolving myocardial infarction (MI), and non-Q wave or subendocardial MI. Although the underlying pathology is similar, management differs and, therefore, ACS is usually divided into 2 classes:
ACS with ST segment elevation or new LBBB (acute MI see p782).
ACS without ST segment elevation (unstable angina or non-Q wave MI).
ACS is associated with a greatly increased risk of MI (up to 30% in the 1st month). Patients should be managed medically until symptoms settle. They are then investigated by angiography with a view to possible angioplasty or surgery (CABG).
Assessment
Brief history:
previous angina, relief with rest/nitrates, history of cardiovascular disease, risk factors for IHD.
Examination:
pulse, BP, JVP, cardiac murmurs, signs of heart failure, peripheral pulses, scars from previous cardiac surgery.
Investigations
ECG: ST depression; flat or inverted T waves; or normal. FBC, U&E, glucose, lipids, cardiac enzymes. CXR.
Measurement of cardiac troponins helps to predict which patients are at risk of a cardiac event, and who can be safely discharged early. Note that 2 different forms of troponin are measured: troponin T and troponin I: they have different reference intervals (consult your lab).
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