Coronary Artery Disease and Acute Coronary Syndromes
This domain carries a large share of the written paper and of the vignette-based items. The exam tests reperfusion timing, NSTE-ACS risk stratification, antithrombotic selection, and secondary-prevention thresholds rather than rote lists of risk factors.
Reperfusion rules for STEMI
- Primary PCI is the default whenever it can be delivered within 120 minutes of first medical contact; door-to-balloon is 90 minutes on site and 120 minutes for transfer.
- If PCI cannot be delivered in time and symptoms began within 12 hours, give fibrinolysis within 30 minutes (door-to-needle) and transfer for angiography, typically 2-24 hours later.
- Absolute contraindications include prior intracranial haemorrhage, recent ischaemic stroke, active bleeding, suspected aortic dissection, and severe uncontrolled hypertension.
NSTE-ACS timing
- Very high risk (shock, refractory pain, acute heart failure, malignant arrhythmia): angiography within 2 hours.
- High risk (dynamic ST-T change, rising troponin, GRACE above 140): within 24 hours.
- Intermediate risk: within 72 hours.
Antithrombotic therapy
- Aspirin loading 150-300 mg, then 75-100 mg lifelong; add ticagrelor or prasugrel in preference to clopidogrel for 12 months by default.
- Shorter DAPT (3-6 months) when bleeding risk dominates; continue aspirin alone afterwards.
Secondary prevention
- High-intensity statin aiming for LDL-C below 55 mg/dL and at least 50% reduction; add ezetimibe, then a PCSK9 inhibitor.
- ACE inhibitor, beta-blocker, and mineralocorticoid receptor antagonist when LVEF is 40% or less with heart failure or diabetes.
Worked example
A 58-year-old man has 3 hours of crushing chest pain with ST elevation in V1-V4 and no bleeding history. If the catheter laboratory is 3 hours away, he receives fibrinolysis within 30 minutes, then transfer; if PCI is achievable within 120 minutes, he goes directly to the laboratory. Either way he starts aspirin plus ticagrelor, a high-intensity statin, a beta-blocker, and an ACE inhibitor.
Traps
- Posterior infarction shows ST depression in V1-V3 with tall R waves; calling it anterior ischaemia and withholding reperfusion is a classic error.
- Diffuse ST elevation with PR depression is pericarditis, and troponin may still rise.
- In cocaine-associated chest pain avoid unopposed beta-blockade; use benzodiazepines and nitrates.
- Do not diagnose reinfarction on troponin alone; use symptoms and ECG.