Angina Pectoris: Understanding Unstable Angina


Angina pectoris, more commonly known as angina, is chest pain or discomfort that occurs when an area of your heart muscle does not receive enough oxygen-rich blood. There are several types of angina, but in this article, our primary focus will be on understanding unstable angina, a condition that requires immediate medical attention due to its potential to escalate into a full-blown heart attack.

Diagram of discomfort caused by coronary artery disease. Pressure, fullness, squeezing, or pain in the center of the chest. You can also feel neck, jaw, shoulders, back, or arms discomfort.
Diagram of discomfort caused by coronary artery disease. Pressure, fullness, squeezing, or pain in the center of the chest. You can also feel neck, jaw, shoulders, back, or arms discomfort.

What is Unstable Angina?

Unstable angina, a type of acute coronary syndrome, is characterized by chest pain or discomfort that occurs unexpectedly, often at rest or with minimal exertion, or at a lower threshold of exertion than the patient’s previous angina (angina “crescendo”). Unlike stable angina, the symptoms of unstable angina are unpredictable and can occur even when a person is at rest, and do not follow any pattern.

The chest discomfort of unstable angina often feels like a pressure, heaviness, tightness, squeezing, burning, or fullness in the center of the chest. It can also present as discomfort or pain in the arms, neck, jaw, shoulder, or back. Unstable angina is a serious condition that requires immediate medical attention as it may indicate an impending heart attack.


Unstable angina is caused by the following mechanisms:

  1. Atherosclerosis: The most common cause of unstable angina is atherosclerosis, a disease where plaque (a combination of cholesterol, fat, calcium, and other substances) builds up in the inner walls of the arteries. Over time, this plaque hardens and narrows the arteries, limiting the flow of oxygen-rich blood to your organs and other parts of your body.
  2. Blood Clots: Sometimes, the plaque on the artery walls can rupture, and blood clots may form around the plaque. These clots can partially or completely block the coronary artery. While the clot may be dissolved by the body’s own defense mechanism, if this process doesn’t happen quickly enough, the reduced blood flow can cause unstable angina or a heart attack.
  3. Coronary Artery Spasm: This is a temporary tightening of the muscles in the artery wall, which can briefly decrease blood flow to the heart but usually does not cause permanent damage. It can trigger episodes of unstable angina, especially in people who have atherosclerosis.

Risk Factors

Certain factors can increase your risk of developing unstable angina. They include:

  1. Age: Men older than 45 and women older than 55 have a greater risk.
  2. Tobacco Use: Smoking and long-term exposure to secondhand smoke damage the interior walls of arteries, allowing cholesterol and other substances to collect and form plaques.
  3. Diabetes: This condition seriously increases the risk of coronary artery disease, which leads to angina and heart attacks.
  4. High Blood Pressure: Over time, high blood pressure can damage arteries by accelerating atherosclerosis.
  5. High Blood Cholesterol Levels: High levels of cholesterol in your blood can increase the risk of the formation of plaques and atherosclerosis.
  6. Sedentary Lifestyle: Lack of physical activity leads to high cholesterol, high blood pressure, type 2 diabetes, and obesity, all of which increase the risk of unstable angina.
  7. Obesity: Obesity raises the risk of angina and heart disease because it’s associated with high blood cholesterol levels, high blood pressure, and diabetes. Also, your heart has to work harder to supply blood to the excess tissue.
  8. Stress: High levels of stress or depression can increase your risk of unstable angina and heart disease.
  9. Family History of Heart Disease: If a close family member had heart disease at an early age, you may be at higher risk.

Diagnosis of Unstable Angina

Diagnosing unstable angina involves a careful evaluation of symptoms, medical history, a physical examination, and several tests to confirm the diagnosis and rule out other potential causes of the symptoms.

  1. Electrocardiogram (ECG): This is the first test done to diagnose unstable angina. It records the electrical activity of the heart and can identify areas of the heart muscle that aren’t receiving enough oxygen.
  2. Blood Tests: Certain heart proteins slowly leak into your blood after heart damage from insufficient oxygen. Detecting these substances in blood tests can suggest a heart attack.
  3. Stress Test: Sometimes also called a treadmill or exercise ECG, this test is done to monitor your heart while you walk on a treadmill or ride a stationary bike. If you’re unable to exercise, you may be given a drug that mimics the effect of exercise on your heart.
  4. Echocardiogram: This test uses sound waves to produce an image of your heart, showing its size, structure, and motion.
  5. Coronary Angiography: This test uses a dye and special X-rays to show the insides of your coronary arteries. It can reveal blockages in the arteries.

Treatment of Unstable Angina

Treating unstable angina involves an immediate response to alleviate symptoms and longer-term strategies to manage the underlying condition. Here’s a more detailed exploration of these approaches:

  1. Medications: Medications play a crucial role in the initial and ongoing treatment of unstable angina. Here are some common types:
    • Antiplatelet drugs such as aspirin and clopidogrel (Plavix) are often the first line of defense, reducing the formation of blood clots and improving blood flow through narrowed coronary arteries.
    • Anticoagulants, like heparin or warfarin, can also be used to prevent blood clotting.
    • Nitrates, such as nitroglycerin, are used to relax and widen the blood vessels, improving blood supply to the heart muscle.
    • Beta-blockers slow the heart rate, reduce blood pressure, and decrease the heart’s demand for oxygen. Examples include atenolol (Tenormin) and metoprolol (Lopressor).
    • Calcium channel blockers, such as diltiazem (Cardizem) and amlodipine (Norvasc), relax and widen blood vessels and decrease heart workload.
    • Statins, like atorvastatin (Lipitor) or rosuvastatin (Crestor), lower cholesterol levels and reduce the potential for plaque build-up in the arteries.
    • Angiotensin-converting enzyme (ACE) inhibitors help relax blood vessels and lower blood pressure, reducing the heart’s workload.
  2. Surgical Procedures: If medications aren’t sufficient, more invasive procedures might be necessary.
    • Percutaneous coronary intervention (PCI), often known as coronary angioplasty, is a non-surgical procedure that opens blocked or narrowed coronary arteries. A thin, flexible catheter is threaded to the affected artery, where a balloon on its tip is inflated to compress the plaque against the artery wall. Often, a mesh tube called a stent is left behind to keep the artery open.
    • Coronary artery bypass grafting (CABG) is a type of surgery that improves blood flow to the heart. It’s performed when the coronary arteries become blocked or damaged. During CABG, a healthy artery or vein from the body is connected, or grafted, to the blocked coronary artery. The grafted artery or vein bypasses the blocked portion of the coronary artery, delivering fresh blood to the heart.
  3. Lifestyle Changes: Beyond medical interventions, adapting your lifestyle is essential for managing unstable angina and preventing future episodes. This can include:
    • Diet: Eating a heart-healthy diet rich in fruits, vegetables, lean proteins, and whole grains, while limiting saturated fats, sugars, and sodium can help manage weight and control blood pressure, cholesterol, and blood sugar levels.
    • Exercise: Regular physical activity strengthens the heart and improves overall cardiovascular health. However, it’s important to consult with a healthcare provider before starting a new exercise regimen.
    • Quitting Smoking: Smoking damages the heart’s blood vessels, lowers good cholesterol levels, and raises blood pressure. Quitting is a crucial step to prevent further heart damage.
    • Stress Management: Chronic stress contributes to heart disease, and learning to manage stress in healthy ways can improve heart health. This might involve relaxation exercises, stress management classes, or therapeutic practices like yoga and meditation.

Complications of Unstable Angina

Untreated or poorly managed unstable angina can lead to serious complications, including:

  1. Heart Attack: This is the most severe complication of unstable angina. If the blood supply to a part of your heart is cut off entirely or for a prolonged period, a heart attack can occur. This can lead to significant damage to the heart muscle and can be life-threatening.
  2. Arrhythmias: Unstable angina can disrupt the normal electrical conduction system of the heart, leading to abnormal heart rhythms, known as arrhythmias. These can be life-threatening if not treated promptly.
  3. Heart Failure: If the heart muscle is significantly damaged, it may weaken to the point where it can’t pump blood efficiently to meet the body’s needs, a condition known as heart failure.

Prognosis of Unstable Angina

The prognosis of unstable angina can vary greatly depending on various factors, including the extent of the heart disease, the individual’s overall health, and how well they manage their condition with lifestyle changes and medication.

Many people with unstable angina, when well-managed, can lead a relatively normal life. However, they will need to make significant lifestyle changes and be diligent about their medication regimen. Regular check-ups with healthcare providers will be necessary for ongoing monitoring and adjustment of treatment.

Despite this, it is crucial to remember that unstable angina is a serious condition that can potentially lead to life-threatening complications. It’s important to take the condition seriously and seek immediate medical help if you experience symptoms.


  1. American Heart Association: Understanding Angina
  2. Mayo Clinic: Angina
  3. WebMD: What Is Angina?
  4. Healthline: Angina Pectoris
  5. MedlinePlus: Angina

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This article is intended for informational purposes only. The content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. If you think you may have a medical emergency, call your doctor or call emergency number immediately.

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Tanzir Islam Britto

Hello, I'm Dr. Tanzir Islam Britto. As a dedicated physician, I've embarked on my medical journey at Bangabandhu Sheikh Mujib Medical College (BSMMC), previously known as Faridpur Medical College, where I pursued my Bachelor of Medicine and Bachelor of Surgery (MBBS). I completed my degree at Shahabuddin Medical College (SMC). Alongside my medical career, I am an amateur writer and an active social media advocate, where I share insights into health, wellness, and more.

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