What is unstable angina?
Unstable angina is a form of acute coronary syndrome in which the heart muscle does not receive enough blood flow and oxygen. It can occur at rest, is less predictable than stable angina, and may not be relieved by rest or usual angina medications. It is a medical emergency because it often precedes a heart attack.
Other types of angina
- Stable angina – predictable chest pain triggered by exertion and relieved by rest or nitroglycerin.
- Variant (Prinzmetal) angina – caused by coronary artery spasms rather than plaque, often occurring at rest.
- Microvascular angina – involves small coronary vessels, with chest pain that can be prolonged and may not respond to typical nitroglycerin.
- Refractory angina – severe chest pain persisting despite optimal medical therapy and lifestyle changes.
Causes
Unstable angina most often results from:
- Rupture of an atherosclerotic plaque, leading to a partially obstructing blood clot
- Severe narrowing of a coronary artery due to plaque buildup
- Coronary artery spasm, temporarily reducing blood flow
Symptoms
- Chest discomfort described as pressure, squeezing, or heaviness
- Pain radiating to the shoulders, arms, neck, jaw, or back
- Shortness of breath
- Sweating
- Nausea or vomiting
- Dizziness or light‒headedness
- Anxiety or feeling of impending doom
Diagnosis
Evaluation includes:
- Medical history and physical examination
- Electrocardiogram to detect ischemic changes
- Blood tests for cardiac biomarkers such as troponin
- Stress testing if initial workup is inconclusive
- Coronary angiography to visualize blockages
Treatment
Immediate management aims to relieve pain, prevent clot growth, and restore blood flow:
- Aspirin and other antiplatelet drugs to reduce clotting
- Anticoagulants such as heparin to prevent clot extension
- Nitrates to dilate coronary arteries
- Beta blockers to lower heart rate and oxygen demand
- ACE inhibitors to reduce cardiac workload
- Statins to stabilize plaques
- Coronary angioplasty with stent placement or bypass surgery for severe blockages
Lifestyle modifications
- Smoking cessation
- Heart-healthy diet low in saturated fat and sodium
- Regular moderate exercise as tolerated
- Weight management
- Stress reduction techniques