Acute Coronary Syndrome

Question 1

What is ACS?

Answer 1

• refers to a spectrum of acute myocardial ischaemia and/or infarction
• 3 categories according to presence/absence of ST segment elevation, together with myocardial biomarkers (troponin, creatine kinase).

STEMI- ST-elevation myocardial infarction, the ECG shows persistent ST-segment elevation in 2 or more leads

Unstable angina and NSTEMI (non-ST-elevation myocardial infarction) represent a continuum of pathology, differing by the presence of markers of myocardial damage in NSTEMI = unstable angina and NSTEMI are ‘non ST-elevation acute coronary syndromes).

Question 2

Related conditions:

1) Unstable angina
2) Myocardial infarction, non ST elevation

Answer 2

1) Unstable angina:
- UA is ACS defined by biochemical myocardial damage
- prolonged (>20 mins) angina at rest
- new onset of severe angina
- angina increasing frequency, longer in duration, occurs after recent MI
- ECG shows ST depression, T-wave inversion, but may be normal
- UA diagnosis if no elevation in creatine kinase-MB or troponin

2) NSTEMI :
- myocyte necrosis
- ST-segment depression, transient ST-elevation, T-wave inversion , may be normal
- elevated biomarkers (unline UA) after hours of NSTEMI

3) STEMI :
- consistent clinical history
- >20mins ST-segment elevation in 2 or more leads or new LBBB
- biomarkers elevated
- prompt revascularisation with percutaneous coronary intervention within 90 minutes of first presentation, or thrombolysis within 12 hrs of symptom onset