Acute Coronary Syndrome (ACS) 

Definition:  

Acute Coronary Syndrome (ACS) is a spectrum of conditions caused by acute myocardial ischaemia due to reduced blood flow in the coronary arteries.  

It includes:  

1. ST-Elevation Myocardial Infarction (STEMI)  
2. Non-ST-Elevation Myocardial Infarction (NSTEMI)  
3. Unstable Angina (UA) 

Pathophysiology:  

– Atherosclerotic plaque rupture → platelet aggregation & thrombus formation.  
– Degree of occlusion:  
– Complete → STEMI
– Partial → NSTEMI
– Transient → UA  
– Less common causes: coronary spasm, embolism, coronary dissection. 

Risk Factors: 

 – Non-modifiable: Age, male sex, family history  
– Modifiable: Hypertension, diabetes, dyslipidemia, smoking, obesity, sedentary lifestyle 

Clinical Features:  

– Typical Chest Pain: Substernal, crushing, radiates to left arm/neck/jaw/back, lasts >20 min, associated with diaphoresis, nausea, vomiting, dyspnoea.  
– Atypical presentations: fatigue, dyspnoea, epigastric discomfort (common in elderly, women, diabetics) 

Investigations:  

1. ECG:  
– STEMI: ST-elevation ≥1 mm in ≥2 contiguous leads or new LBBB  
– NSTEMI/UA: ST depression, T-wave inversion, or normal 2. Cardiac biomarkers  
– Troponin I/T: elevated in MI, normal in UA  
– CK-MB: less specific  

3. Other tests: FBC, electrolytes, renal function, chest X-ray, echocardiography, coronary angiography 
Classification Table:  

Management:  

1. Initial (ABC + MONA): 

– Airway, Breathing, Circulation  
– Morphine, Oxygen (if SpO₂ < 90%), Nitrates, Aspirin  

2. Antiplatelets:  
Dual therapy (Aspirin + P2Y12 inhibitor)  

3. Anticoagulation:  
UFH, LMWH, fondaparinux  

4. Reperfusion:  
– STEMI: Primary PCI within 90 min or thrombolysis if PCI unavailable  
– NSTEMI/UA: Risk stratification; PCI if high-risk  

5. Supportive therapy:  
Beta-blockers, ACE inhibitors, statins, lifestyle modification 

Complications:  
– Arrhythmias, heart failure, cardiogenic shock, mechanical complications, pericarditis 

Key Points:  

– ACS is a spectrum.  
– STEMI = emergency → immediate reperfusion. 
 – NSTEMI/UA = partial occlusion → urgent management.  
– ECG + troponin guide diagnosis. 
– Early recognition prevents permanent damage and treatment save lives.