ECG in Chest Pain and Breathlessness

*Key Diagnostic Features of Chest Pain*

- Radiation to the jaw/teeth → Likely cardiac (e.g., myocardial ischaemia)

- Worse on inspiration → Suggests pleuritic pain or pericarditis

- Pain in the back → Consider aortic dissection or myocardial ischaemia

ThECG helps differentiate these causes but is not always definitive. For example, aortic dissection can affect coronary artery ostia, leading to myocardial ischaemia.

Acute Coronary Syndromes (ACS)

- ACS results from atheromatous plaque rupture and thrombus formation, leading to partial or total coronary occlusion.

- It includes unstable angina, myocardial infarction (MI), and sudden death.

Diagnostic Criteria for ACS

✔️ Clinical presentation (e.g., chest pain, history of coronary artery disease).

✔️ ECG changes indicative of myocardial ischaemia.

✔️ Biochemical markers (troponin levels):

- Unstable angina: ECG changes + normal troponin.

- Myocardial infarction (MI): ECG changes + elevated troponin (which may take up to 12 hours to rise).

Types of Myocardial Infarction & ECG Findings

🩸 ST-Elevation Myocardial Infarction (STEMI)

- Defined by ST-segment elevation** on ECG

- Requires urgent reperfusion therapy** (PCI or thrombolysis) within 6 hours for maximal benefit.

🩸 Non-ST Elevation Myocardial Infarction (NSTEMI)

- No ST elevation, but ECG may show ST depression or T wave inversion

- Managed with antiplatelets, anticoagulation, and risk stratification rather than immediate reperfusion.

Key Takeaways

✔️ ECG is essential in ACS diagnosis and determines management.

✔️ STEMI vs NSTEMI differentiation is crucial, as STEMI needs immediate intervention.

✔️ **Troponin may take up to 12 hours to rise**, so serial measurements are needed.

✔️ Consider **alternative diagnoses** (e.g., pericarditis, dissection) in non-classic presentations.