Cardiology
Acute coronary syndromes
Written 30 September 2026.
Why this matters
A coronary plaque event is a time-sensitive diagnosis. The first ECG changes what happens next.
Rapid clinical summary
- Suspected ACS means urgent ECG and assessment, not a booked treadmill.
- ST elevation in a territory is a reperfusion decision.
- Absence of ST elevation does not mean the pain is benign.
Mechanism
A plaque tears or erodes. Thrombus narrows or closes the artery. Muscle downstream becomes ischemic. The ECG shows the electrical consequence; the story shows the clinical one.
Recognition
Pressure that is still there, with autonomic features, is ACS until the assessment says otherwise.
Typical
- Central pressure
- Radiation to arm or jaw
- Sweat, nausea, breathlessness
Red flags
- Ongoing pain
- Shock
- Pulmonary edema
- A new murmur
- A rhythm that is not perfusing
Differential
| Condition | Clue | Trap |
|---|---|---|
| Pericarditis | Positional pain, widespread concave ST change, PR depression | Giving a reperfusion drug for pericarditis |
| Dissection | Tearing pain, deficit in a pulse | Missing it because an ECG was done and looked non-specific |
| Esophageal spasm | Can mimic pressure | Using it as a discharge diagnosis while pain continues |
Investigations
- ECG at once, and repeat it if pain continues or returns.
- Blood tests for injury support a later diagnosis. They do not replace the first ECG.
Management
- Immediate
- Monitor, treat pain and instability according to the local emergency pathway, and decide whether this is a reperfusion ECG.
- Definitive
- Reperfusion for occlusion. For other ACS, the pathway is antithrombotic treatment and a decision about angiography timing. Doses are not stated here.
- Monitoring
- Watch for recurrence of pain, heart failure, and arrhythmia. A single relieved episode still needs the pathway, not a corridor discharge.
Common pitfalls
- Waiting for a blood test before the ECG.
- Calling a normal early blood test a rule-out while pain continues.
- Equating ‘no ST elevation’ with ‘not cardiac’.
Exam reasoning
The question is usually the next action in a patient who is still in pain, or the ECG pattern that must not be treated as infarction.
Practice this topicOpens original Mahazanaka questions in this subject. If this subject is thin on that track, the session uses what exists.
Visual summary
The ECG decides the next door, not a later clinic.
Recognize, reason, prioritize, act safely
- Recognize. Ischemic pain, still present.
- Reason. Is the artery likely closed on this ECG, or is this another dangerous chest pain?
- Prioritize. Reperfusion timing if it is occlusion. Do not discharge the rest.
- Act safely. Urgent pathway. Not next week’s test.
Knowledge check
Pain has lasted 40 minutes and is still present. What is the first investigation?
Why is a normal oxygen saturation a poor argument for discharge?
No citation is attached to this chapter. Nothing here is personal medical advice.