What to Know About Unstable Angina

Medically Reviewed by James Beckerman, MD, FACC on October 21, 2021
3 min read

Angina happens when one of the heart’s blood vessels is blocked and temporarily deprives the heart muscle of blood and oxygen, causing chest pain. If you feel like someone is squeezing your heart when you're stressed or have sudden pain in your left arm, you may be experiencing angina. Even if you have angina that only lasts for a few moments, you should speak with a doctor to determine if it might be a warning sign of coronary artery disease. Read on to learn more about unstable angina and how to manage your symptoms.

When plaque — a deposit of cholesterol, fat, and other substances — builds up inside your arteries, the artery walls narrow and become rigid, reducing blood flow to your heart. This reduced blood flow can bring on sudden chest pain

The lack of blood flow to the heart causes angina — a symptom of coronary artery disease. The pressure and squeezing it causes can feel like a heart attack. 

Stable angina is the most common type and typically occurs when you feel emotional stress or physically overexert yourself. The chest pain or discomfort caused by stable angina should subside with rest and — if necessary — medication prescribed by your doctor.

By contrast, unstable angina is sudden and can happen while you're resting. Unstable angina might also occur if symptoms of angina are new or have suddenly increased in frequency or severity. Having unstable angina typically means the blockage in your arteries has reached a critical level. As a result, chest pain and discomfort become more persistent and severe. 

Unstable angina is a life-threatening emergency — rest or medicine will not help relieve your condition, and the pain will worsen over time. Call 911 if you have chest pain or discomfort while at rest, as well as:

  • A dull ache or heaviness that spreads down your arms, back, shoulder, or jaw
  • Shortness of breath
  • Nausea
  • Sweating
  • Fatigue

Coronary heart disease is the principal cause of unstable angina. Left untreated, a clot can completely block an artery, leading to a heart attack or heart failure. 

The risk of having unstable angina increases with age. It is more common in men ages 45 and older and in women ages 55 and older. The risk is higher if a person: 

  • Smokes
  • Doesn't exercise
  • Has a family history of heart disease
  • Has diabetes
  • Has high blood pressure
  • Has high cholesterol levels

Eating a healthier diet, losing weight, lowering stress, and quitting smoking can lessen your chances of developing and experiencing unstable angina. Talk to your doctor about a treatment plan to improve your heart health. 

Because unstable angina is a medical emergency, you will first be treated with painkillers and aspirin to prevent blood clots. 

You will then have a procedure called a cardiac catheterization in which you will be given a nitroglycerin capsule to widen your heart's blood vessels. During the procedure, the doctor guides a catheter through an artery in your arm, groin, or leg and into the coronary arteries. The catheter is then injected with a liquid dye, and a high-speed X-ray records the course of the dye as it makes its way through your arteries, allowing the doctor to trace the flow and identify blockages. 

The severity of your coronary artery blockage will determine the course of treatment. If the blockage has reached a critical stage, your doctor will likely recommend an angioplasty, a procedure in which a small tube, also known as a stent, is inserted in the artery to keep it open.

Your doctor may also recommend heart bypass surgery, a procedure that reroutes blood flow away from the blocked artery, improving overall blood flow to your heart. 

Common treatments for unstable angina include blood thinners like heparin, clopidogrel, and aspirin. Medications that reduce blood pressure or cholesterol levels may also be prescribed to reduce symptoms of angina.