Unstable Angina  

Definition: Unstable angina (UA) is an acute coronary syndrome characterized by sudden reduced blood flow to the myocardium, usually due to partial coronary artery blockage, without causing myocardial necrosis. It is a medical emergency and requires prompt recognition. 

Key Features:  

– Chest pain at rest or with minimal exertion.  
– New onset or change in pattern of existing angina.  
– Not relieved by rest or usual medications.  
– Cardiac biomarkers (troponin, CK-MB) are normal. 

Pathophysiology:  

1. Rupture of an atherosclerotic plaque.  
2. Formation of a partial thrombus.  
3. Reduced oxygen supply to myocardium → ischaemia.  
4. No full-thickness myocardial cell death (distinguishes UA from MI). 

Clinical Features:  

– Retrosternal chest pressure, heaviness, or squeezing.  
– Radiation to left arm, neck, jaw, or back.  
– Associated symptoms: dyspnea, diaphoresis, nausea, lightheadedness.  
– May occur at rest or with minimal exertion. 

Diagnosis:  

– History: Most important for initial recognition. 
 – ECG: ST-segment depression or T-wave inversion; no ST-elevation.  
– Cardiac biomarkers: Normal. 
– Risk stratification: TIMI score helps predict prognosis. 

Management:  

Immediate Treatment:  

– Oxygen (if hypoxic).  
– Aspirin (antiplatelet).  
– Nitroglycerin (sublingual or IV).  
– Morphine for persistent pain. 
 – Beta-blockers (unless contraindicated).  
– Anticoagulation: Heparin or LMWH. 

Long-term Management:  

– Lifestyle modification: smoking cessation, diet, exercise.  
– Statin therapy. – Dual antiplatelet therapy if stent placement.  
– Revascularization (PCI or CABG) for high-risk patients. 

Complications / Red Flags:  

– Progression to NSTEMI or STEMI.  
– Arrhythmias.  
– Heart failure. 

References:  

Braunwald E. Heart Disease: A Textbook of Cardiovascular Medicine, 11th Edition.  
Libby P, et al. Circulation. 2019;139:e56–e528.