17.12: Angina II: Classification

Angina, also known as angina pectoris, is a chest pain resulting from diminished blood flow to the heart muscle and is often a symptom of coronary artery disease. Angina presents several variants with distinctive attributes, etiologies, and therapeutic approaches. The main types of angina include stable, unstable, variant (Prinzmetal's), microvascular, intractable, and silent ischemia.

• Stable angina is caused by atherosclerosis, which leads to the formation of plaques that narrow the coronary arteries and diminish blood flow to the heart muscle. Its characteristics include a predictable chest pain or discomfort pattern, usually occurring during physical activity or emotional stress, and decreased by rest or nitroglycerin. Nitroglycerin dilates the coronary arteries and reduces the heart's workload, quickly relieving symptoms. The chest pain may radiate or spread to the shoulders, upper arms, neck, jaw, or back, typically lasting 5-15 minutes.
• Microvascular angina impacts the small coronary arteries and is often linked to endothelial dysfunction, which reduces blood flow in the microvasculature. The chest pain experienced with microvascular angina can occur during physical exertion or at rest. This pain can be prolonged and may feel more intense than the pain experienced in stable angina. It is less predictable and only sometimes relieved by rest or nitroglycerin. Microvascular angina is more common in women.
• Prinzmetal's angina, also known as variant angina, is caused by the inability to dilate or experience spasms in the coronary arteries, temporarily reducing blood flow to the heart muscle. These spasms can occur in arteries that are not significantly narrowed by atherosclerosis. The severe chest pain associated with Prinzmetal's angina typically occurs at rest, often during the night or early morning, and can last from 5 to 30 minutes. It may be associated with arrhythmias or transient ST-segment elevation on an ECG and is typically relieved by calcium channel blockers or nitroglycerin.
• Unstable angina occurs when atherosclerotic plaque ruptures, causing partial or complete blockage of a coronary artery. Its characteristics include the new onset of chest pain, worsening of previously stable angina, or chest pain at rest. The pain is more severe, prolonged, and less predictable than stable angina, and it is not relieved by rest or nitroglycerin. Due to potential complete blockage of the coronary artery, unstable angina poses a high risk of progressing to a heart attack.
• Intractable or refractory angina is characterized by persistent angina despite optimal medical therapy and revascularization procedures. It is often associated with severe coronary artery disease or microvascular dysfunction. Patients with intractable angina experience chronic, debilitating chest pain that may be constant or occur frequently.
• Silent ischemia refers to ischemia without the typical symptoms of angina, often detected incidentally during ECG or other diagnostic tests. It can occur due to atherosclerosis, diabetes, hypertension, or additional risk factors for coronary artery disease[CAD]. Individuals with silent ischemia do not experience the chest pain or discomfort typically associated with angina. Instead, silent ischemia may be identified through stress tests, Holter monitoring, or other diagnostic tools. Managing risk factors such as diabetes and hypertension is crucial to prevent silent ischemia.