Unstable Angina: Causes, Symptoms and Prevention

What is Unstable Angina? 

Unstable angina is a situation where the coronary blockages have progressed to a point where the blood supply is critically reduced to the heart. So the person experiences symptoms either at minimal physical activity or even at rest. Sometimes a patient with unstable angina may not manifests with chest pain, and rather present symptoms like breathlessness, pain in the left arm, or jaw pain. So chest pain is not always a manifestation of unstable angina.

What causes Unstable Angina?

If fat-containing deposits (plaques) in a blood vessel rupture and blood clots are formed, it can quickly block or reduce the flow through a narrowed artery, suddenly and severely decreasing blood flow to the heart muscle. Unstable angina can also be caused by blood clots that block or partially block the heart's blood vessels.

What are the characteristic symptoms of Unstable Angina?

Characteristics of unstable angina (a medical emergency) include:

    1. Can occur even at rest
    2. There is a change in the usual pattern of angina
    3. Is often unexpected
    4. Is usually more severe and lasts longer than stable angina, maybe as long as 30 minutes
    5. May not disappear with rest or use of angina medication
    6. Might signal a heart attack

How can Unstable Angina be diagnosed and managed?

Unstable angina worsens and is often not relieved by rest or usual angina medications. If the blood flow doesn't improve, the heart muscle deprived of oxygen dies — a heart attack. Unstable angina is dangerous and requires emergency treatment.

If a patient with Unstable angina has no ECG changes and the cardiac enzymes particularly troponin are negative on multiple occasions when tested 6 hours apart – then it may be considered as a low risk Unstable angina. Such patients may be subjected to a stress test. However, if a patient with unstable angina has dynamic ECG changes, blood pressure fluctuations and elevated cardiac enzymes, then such patients should not be subjected to stress tests because this can precipitate a heart attack. Such patients should be advised a cardiac catheterization or coronary angiography for assessment.

Dr. Sreekanth B. Shetty
Senior Consultant & Head - Interventional Cardiology
MD (Internal-Medicine), DM (Cardiology)
Institute of Cardiac Sciences