• Angina pectoris (literally heart pain) is characterized by paroxysmal and usually recurrent attacks of substernal or precordial chest discomfort caused by transient myocardial ischemia.
• The three overlapping patterns of angina pectoris : 1. Stable or typical angina 2. Prinzmetal variant angina 3. Unstable or crescendo angina

Stable angina :

• It is the most common form and is also called typical angina pectoris
• Cause : an imbalance in coronary perfusion (due to chronic stenosing coronary atherosclerosis) relative to myocardial demand, such as that produced by physical activity, emotional excitement or any other cause of increased workload.
• Typical angina pectoris is usually relieved by rest or administering nitroglycerin (a vasodilator that increases perfusion)
• Pharmacology – nitroglycerin is the drug of choice, administered sublingually with an initial dose of 0.5 mg, which usually relieves pain in 2-3 minutes.

Prinzmetal variant angina :

• It is an uncommon form of episodic myocardial ischemia
• Cause : coronary artery spasm
• It is unrelated to physical activity, heart rate or blood pressure
• Pharmacology – episodes of coronary vasospasm are treated with nitrates; for prophylaxis, nitrates and calcium channel blockers (Amlodipine, nifedipine and diltiazem) are effective.

Unstable or Crescendo angina :

• It refers to a pattern of increasingly frequent pain of prolonged duratio, that is precipitated by progressively lower levels of physical activity or that even occurs at rest
• Cause : mostly by disruption of an atherosclerotic plaque with superimposed partial thrombosis and possibly embolization or vasospasm (or both)
• Unstable angina thus serves as a warning that an acute MI may be imminent; indeed, this syndrome is sometimes referred to as preinfarction angina.
• Pharmacology – it requires treatment with multiple drugs – antiplatelet drugs, anticoagulants, nitrates, beta blockers, CCBs and statins

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Source : Robbins and Cotran’s book of pathology