Angina II: Classification

Stable angina occurs when coronary arteries narrow due to atherosclerosis, reducing blood flow to the heart. It causes predictable chest pain during physical activity or emotional stress, lasting 5-15 minutes. The pain radiates to the shoulders, arms, neck, jaw, or back and is relieved by rest or nitroglycerin, which dilates coronary arteries and reduces the heart's workload.

Microvascular angina affects small distal coronary artery branches that fail to dilate properly or experience spasms, reducing blood flow. Unlike stable angina, it causes severe, prolonged chest pain that is less predictable and often not relieved by rest or nitroglycerin. Microvascular angina is more common in women and is linked to endothelial dysfunction.

Prinzmetal angina, also called variant angina, results from sudden coronary artery spasms that temporarily reduce blood flow, even in arteries without significant atherosclerotic narrowing. Severe chest pain typically occurs at rest, often during night or early morning, lasting 5-30 minutes. It is relieved by calcium channel blockers or nitroglycerin and may be associated with arrhythmias or ST-segment elevation on an ECG.

Unstable angina occurs when atherosclerotic plaque ruptures, causing partial or complete coronary artery blockage. It presents as new-onset chest pain, worsening of previously stable angina, or pain at rest. The pain is severe, prolonged, and not relieved by rest or nitroglycerin, posing high risk of progression to myocardial infarction.

Stable and Prinzmetal angina respond well to medications: stable angina improves with rest or nitroglycerin, while Prinzmetal angina responds to calcium channel blockers or nitroglycerin. Microvascular and unstable angina are less responsive to standard treatments. Understanding these distinctions helps guide appropriate therapeutic approaches for each angina classification.

Providers assess angina through patient history, symptom patterns, and diagnostic testing. Stable angina shows predictable triggers and relief with rest; Prinzmetal occurs at night with ST changes; microvascular presents with prolonged pain unrelieved by standard therapy. Clinical manifestations and assessment tools help distinguish types, guiding appropriate management strategies for each patient.

Endothelial dysfunction in microvascular angina impairs the ability of small coronary arteries to dilate properly, reducing blood flow to the heart muscle. This dysfunction causes severe, unpredictable chest pain that may occur during exertion or at rest. Unlike atherosclerotic stable angina, microvascular angina involves microvasculature dysfunction rather than plaque-induced narrowing.